In June 2020, the team coordinating the Homemade Mask Virtual Summit at Tulane University interviewed Dr. Songer about the science behind masks and invited Dr. Songer to give the Keynote Address for the summit. This post contains the audio and transcripts of Dr. Songer’s Keynote Speech: “Masks Unmasked: A Look at the Science Behind Fabric Masks for COVID-19” as well for the two interviews with Dr. Songer for the JustWannaQuilt Podcast. The “Homemade Mask Guide“, created in collaboration with both scientists and sewists after the summit is also included.
Keynote Address for the Homemade Mask Summit
Speaker Introduction: Dr. Jocelyn Songer is the founder of MakerMask.org, a group of volunteers providing science-based mask information and designs to community mask makers by studying and testing them. She holds a BS and MS in Biomedical Engineering from Worcester Polytechnic Institute and a PhD in Speech and Hearing Bioscience and Technology from MIT.
Keynote: “Masks Unmasked: A Look at the Science Behind Fabric Masks for COVID-19”
Dr. Jocelyn Songer
June 17, 2020
Keynote Speech Transcript
This has been edited for clarity and brevity. Each numbered subheading refers to a slide number
Audio Available at: https://www.spreaker.com/user/10136802/hmms-part-1-6-18-20-11-06-am
1. Masks Unmasked (Illustration: 3 MakerMask Designs)
It was really fun listening into the last couple talks. I absolutely agree that masks are awesome and that perfect is the enemy of the good. That’s something I remind myself all the time; it’s not worth trying to make things perfect if you can’t get anything done. So the masks and emergency equipment that you have with you that you’re willing to wear is always going to be the best mask.
2. Thank You! (Illustration: Sewing Superhero)
I just wanted to say thank you “sew”, so much. None of us expected for sewists to be put on the front lines of equipment that everybody needs to be safe from this pandemic. But when global supply chains failed, sewists and others stepped up. I wanted to put in here how many masks we collectively have made. It highlights a little bit of the challenge with the science because it’s really hard to get solid numbers on that. At least, I wasn’t able to. It was like 70,000, 80,000, 100,000, but we don’t have any good totals of how many masks are out there that we’ve made, what they’re all made of, and all of that. But anyway, thank you “sew”, so much; you are true heroes of this pandemic and of 2020. I appreciate you and I know everyone else does as well.
3. My Story: A culture of Sewing (Vintage Postcard: Sewing in Orange c. 1880)
I am from a small town called Orange, Massachusetts. It is the home of New Home Sewing Machine. They started manufacturing sewing machines in my town in 1860. So sewing was a part of the culture that I grew up in. My grandma was a seamstress; my mom sewed all my clothes for me as a kid; she also sewed my prom dress and my wedding dress. I don’t think of myself as an awesome sewist, but I don’t remember a time when I didn’t know how to sew. My mom and my grandma constantly lecture me to stop sewing with a lead foot – if I want straight seams, I have to slow down.
4. My Story: Science & Engineering (Photo: Dr. Songer in the OR)
I know Whitney gave me a great introduction talking about my background as an engineer. I also have a background as a first responder; I used to be an EMT, and I maintain a current first responder training. So I never leave my house without some personal protective equipment and masks in general. I always have a sewing kit.
5. My Story: Occupational Asthma (Photo: Dr. Songer on Mt. Katahdin, AT 2013)
I was going along with my life in academia between engineering and biomedical stuff, and I developed occupational asthma; I was literally allergic to my job. So then instead of just having to use masks for work, I had to wear them for my own health. I got fitted with N95s and took contamination showers every day, but it wasn’t quite enough. My pulmonologist gave me a choice: I could either keep breathing or keep my job. So I left my job to go hike the Appalachian Trail and get my health back.
6. My Story: Backcountry Masks (Photo: Dr. Songer on PCT and CDT with Masks)
That is when I first started having some MacGyver masks and figuring out how to make a face mask that would filter smoke. Because while I was out backpacking the Pacific Crest Trail and the Continental Divide Trail, there were massive forest fires. I didn’t have access to supply chains for face masks because it would be another five days until I get to town. So I had to figure out how to make do with what I had. So I used two layers of my bandana hoping that it would work to filter out some of that smoke. It doesn’t work very well. So that sort of forced me to start improvising through other options with the materials and fabrics I had.
Then when I got off the trail, I did a whole bunch of research on masks and what the ideal combinations were. I think I purchased every single reusable facemask that was on the market at the time. So now I have a stack of all these different reusable facemasks, and I kind of had a sense of what did and didn’t work and what I liked and didn’t like. Masks with exhalation valves work well in a lot of situations like forests when you’re dealing with smoke; they don’t work great for infection control. What we’re using masks for now is to keep our germs to ourselves, essentially, and the exhalation valve just spews everything past the filter into the environment.
When we started to see supply chain shortages, I started working with my mom who’s an RN and a risk manager on researching and designing masks for COVID-19; trying to figure out what the best available information was and how to move forward; make sure that we could get these masks out to the loved ones in our community.
COVID-19 and Masks: Overview
7. Research on Handmade Masks Pre-COVID (Photo and Data from Research)
If you were doing research on handmade masks before COVID, you probably came across the same two studies: The one the CDC pointed everyone to that said it’s possible that we might end up wanting masks and not be able to get them in a pandemic – which turned out to be prophetic – and they gave this one pattern. In all of the literature at the time, I could only find one pattern for a handmade mask for an eight-layer cotton t-shirt mask. Calling it a pattern was perhaps a little bit of a stretch. It’s a picture of how they did the ties on it and sort of mentioning how they crisscrossed the t-shirt layers. That was the primary article the CDC cited. There was another one saying: Here are your fabric options: sweatshirt, t-shirt, towel or scarf.
Of those, they said the towel would be the best. I thought we had to be able to do better than a towel because towels wrapped around your face are not easy to breathe through and work with. If you’ve had the experience of hiking 100 days through the desert with a facemask, you’ll know that there’s a whole lot more to a facemask than whether or not it can pass a particle count; you have to be able to wear it, and wearing a really heavy, bulky mask for long periods of time isn’t practical for most people. So I looked at that research and said let’s see if we can do better. The next thing that was important was seeing what we knew about how COVID was being spread.
8. COVID-19 (SARS-CoV-2) is primarily transmitted via respiratory droplets
The WHO, CDC and all the research we have so far suggests that COVID-19 is primarily spread via respiratory droplets. There’s a figure here that was originally for Ebola but is also true for COVID showing that the droplets spread around six feet. If you’re talking about something that is airborne and truly aerosol driven, the distance that you’re talking about is 30 feet instead of 6. So the main thing we wanted our masks to do was to block droplets.
In Healthcare Settings, Medical Masks are Used for Droplet Precautions
I know that the previous speaker was talking about focusing on masks for the general public and not on the kinds of masks that you need in healthcare settings, and I was kind of interested in bridging that gap. Right now in healthcare settings, medical masks are used as droplet precautions. What that means is that depending how a disease is transmitted, there are different recommendations and guidelines for the precautions that you need to take so as to keep you safe as well as your patients.
So, the kind of mask that is suggested for things that are droplet-based is usually a surgical mask because they block those large droplets that we were talking about.
9. Anatomy of a Mask
Flexible nosepiece to help get a better fit across the bridge of the nose; ear loops (must be latex-free because a lot of elastic has latex in it and a lot of healthcare providers have latex allergies); body of the mask.
A lot of the dialog focuses on particle filtration, but for droplet precautions, fluid resistance is a key component of the mask requirement, as is breathability. The way that you test this if you’re trying to attain a surgical mask certification is with blood – synthetic blood at 80mm mercury pressure sprayed at it. So one of the things that I’m hoping to get dialog on with some of the regulatory agencies is setting up standards that are not surgical masks so you don’t have to have it withstand 80mm of mercury blood, but they’re still fluid resistant. If you’re getting sneezed or coughed at, or somebody spits at you, it’s not coming at that same high pressure.
I see a lot of masks online and in the news that are worn upside down where the pleats are backwards. The waterfall pleats should fall away from your nose. If the mask is upside down, that leads to the possibility of things getting caught up in those pleats instead of falling off and away from them. I call those tide pool pleats because they gather things inside the mask.
10. For the General Public, Fabric Masks are Used to Prevent the Spread of Droplets
When we’re looking at facemasks for the general public, the WHO and the CDC now agree that we should be using facemasks in general and that these facemasks are designed to prevent or reduce the spread of COVID-19. So you place your face covering on to protect other people, and they place their face covering on to protect you. So that’s the intended use for facemasks now. The FDA says that when you’re talking about fabric masks and cloth face coverings, you should remind people that they’re not replacements for social distancing and hand hygiene.
11. Research: Face Masks Help Reduce the Spread of COVID-19!
In just the last couple weeks we’re getting some studies coming out that say yes, indeed, the facemasks are working. Not only do medical masks help but cloth facemasks and fabric masks also help. A study of 172 articles is what made the WHO change their mind and say yes, we do recommend fabric masks.
Just within the week we got this new study saying that wearing a facemask in public corresponds to the most effective means to prevent human transmission of COVID-19. That is pretty huge. They show that within a month, 70,000 infections were prevented in Italy and 66,000 in New York. Looking at these graphs, on the left there’s a picture of data from the US that shows the effect of social distancing at flattening the curve, and on the right they show the data from New York City which shows that instead of just flattening the curve, putting in the facemasks requirements and getting people to adopt facemasks on a large scale crushed the curve; instead of being flat, you got a decrease in infection.
So, the fabric masks that we’ve been making, they have helped and they are helping. The data is finally coming through showing that. We are making a difference, and that is awesome and important.
Mask design Requirements
12. My Fabric Mask Requirements: Water-Resistant, Breathable, Washable, and Latex-Free
I founded MakerMask. My mom and I designed some masks as we were going through the options. The requirements I was looking for were that they be water resistant, breathable, washable and latex-free. The big difference there compared to most medical masks is washable, because in healthcare settings masks are traditionally single use. That’s led to some interesting design features. One big challenge because I was looking for water-resistant materials was balancing water resistance and breathability because those two things do not usually get along; waterproof is not breathable, and breathable waterproof materials aren’t really waterproof. So that’s an interesting tradeoff. From my backpacking experience I had already done a bunch of research into different fabrics where you can get this tradeoff.
13. Spunbond Nonwoven Polypropylene
I ended up landing on nonwoven polypropylene. Spunbond is the kind of polypropylene you’re looking for, and we like it synthetic not woven. That combination allows it to be breathable, which is good. Nonwoven structure helps with filtration; nonwoven materials tend to be better at the mechanical filtration component. The nonwoven polypropylene (NWPP) materials are water resistant; they’re naturally hydrophobic. The spunbond nature of the fabric has better structural integrity and is continuous fibers. A lot of you who’ve been paying attention to mask filter materials have probably heard about meltblown polypropylene as well, which uses smaller, more discontinuous fibers that don’t hold up to washing. The fibers can shrink and compress, and you lose breathability. So that’s how I ended up with that spunbond NWPP. The other advantage to the NWPP at the time was that I had it lying around the house; I could source it from reusable grocery bags that I had or from a whole bunch of other options.
14. CDC Guidance on Cloth Face Masks
I could give a three-hour talk just on NWPP, how it’s made, it’s features. Ideally, we would be using medical-grade NWPP, which we can’t get because of global sourcing issues. My next criteria was food-grade NWPP because it’s designed to touch food and gives you some better hazard analysis parameters, essentially. There are other materials that are heavier and others that look similar that aren’t quite as good, so you need to make sure you check breathability. Maybe we can find a time to talk about all the dos and don’ts of how you go about making those finer choices.
On the CDC’s webpage, they say masks need to be multilayer. They’re recommending tightly-woven cotton. All of their designs are cotton, which is an absorbent material, which is good at containing your droplets and keeping them to you. I don’t want to talk about their bandana mask design because it drives me nuts.
So, it has to be multiple layers; you should check to make sure it’s breathable and washable. The FDA requires that you include a label in the skin-contacting material with washing and disinfecting instructions.
WHO Guidance on Fabric Masks
15. WHO Guidance on Fabric Masks
There is a lot of discussion about the WHO guidance and why they recommend what they do. They recommend at least three layers of mask materials with an outer-most layer that’s hydrophobic (water resistant. The way people measure it is by looking at how well water beads up on the surface of the material. If you can see a full bead of water sitting on top of the material, that’s hydrophobic; if water absorbs into the material like a paper towel, that’s hydrophilic. Hydrophobic and water resistant tend to mean the same thing, and hydrophilic and absorbent mean roughly the same thing as well. Synthetic materials, for the most part, are hydrophobic. Silk and cotton fibers are hydrophilic. Flicking a bead of water at it is the way I tend to make my first approximation. Pour 5ml of water from a teaspoon to see if it drains through within 60 seconds is the more quantitative way of assessing that.
When the WHO guidance is saying polypropylene or polyester, those materials are selected because they’ve tested them and they have that hydrophobic property in the threads. If you have a knit t-shirt with holes in it that’s made out of polypropylene or polyester, even though the fibers don’t absorb water, the material isn’t water resistant so the water can go through the holes.
Elizabeth Townsend Gard, Host: So if you’re shopping somewhere like Jo-Ann’s, they’ll say what it’s made out of, so this is very helpful in terms of moving forward. So this is doable for us as sellers.
Songer: Absolutely! We have already talked for 2.5 hours and this is another half an hour, but I would love to gather information and have some more conversations so we can bridge some of the communication gaps across the communities.
ETG: One of the things is to put out a Best Practices for the sewing community that’s very short and simple but helps people understand how to pick the fabric and what the key things are. I’d love for you to work with us on that. It’s basically what you’re doing but put it into sewing language so that we can actually have this discourse. I really do believe that you help us make this very difficult bridge between the science and the sewing community.
Songer: For that outermost layer with the waterfall pleats, if you can, you want things to hit it and drop down and away instead of getting absorbed into the mask and held close to your face. So the goal of the outer-most layer is to prevent things from going into the absorbent layers. The WHO is specific in suggesting that the outer-most layer be hydrophobic. That’s a pretty major difference from the recommendations we were seeing before this new guidance. Those were 100% focused on source control – containing the user’s droplets. That’s still the intended use for all of these masks, but it’s raising the possibility that you might actually be able to prevent at least some stuff from coming through the other way.
For the middle layer, you can go either way. They say either use a hydrophilic layer like cotton or a cotton blend that will absorb the user’s droplets or use a hydrophobic nonwoven material which will enhance filtration. They say that because nonwoven materials have a much more chaotic structure and do better at mechanical filtration than woven materials because woven materials tend to have holes that go straight through in a more organized way. So if you’re used to doing materials at different angles, that mismatch of how the fibers are formed together gives you better filtration. There’s lots of literature on the different nonwoven materials, but that’s the rationale there.
For the inner-most layer in masks for general use and for surgical masks as well, that is designed to contain user droplets. So, they recommend a hydrophilic or more absorbent material like cotton.
16. WHO Fabric Masks: Choosing Fabric Materials
One of the differences between the guidance we got from the CDC and what we’ve heard from the WHO is that the WHO starts giving us actual criteria for how we should be choosing materials for fabric masks. The reason why they select among NWPP, polyester and cotton in specific is because of a new study that came out in ACS showing the balance between filtration and breathability – those two things can be measured separately, but in order to kind of look at them both together, they ask you to look at the filter quality factor because that combines both metrics in one. So, the higher the Q value, the better. You want Q values for the materials you’re using to be greater than 3. That is a criteria that we can look for to have a good balance between filtration and breathability. Because if you can’t breathe through it, it doesn’t matter how good the filtration is; you can’t use it in a mask.
They show the Quality factor for three different cotton materials, a silk material, nylon (which doesn’t do very well at all,) and polyester, and spunbond nonwoven polypropylene. For each material, they show the initial value off the shelf, and then they check to see if you can improve Q values with an electrostatic charge. You can think about it as static electricity. That’s what they test in this particular study. Back in high school/college physics, you’d do demonstrations rubbing materials against a rubber rod and build up a charge on it and then show that the material gets a static charge and keeps it for some amount of time. When you do that with cotton, it doesn’t build up and hold an electrical charge; if you do it with a hydrophobic material like polyester or polypropylene, not only does it hold a charge initially; it can keep the charge. Polypropylene was able to do that for longer than anything else. That allows it to be better at filtering. The thing that was most interesting about that electrostatic charge part is that they show that even when it started to get humid, the charge on polypropylene remained for over an hour. So it’s possible that there might be some practical applications for home users being able to electrostatically charge their masks. As an electrical engineer, it’s fascinating; I’m really interested to see how that pans out long term.
ETG: I don’t really understand how it only lasts an hour. How are you supposed to recharge it? Are you supposed to have a bunch of masks with you?
Songer: I think that’s a fair concern, and it’s something I’m not sure about, either. They were showing that if you had a pair of vinyl or latex gloves and you rubbed your polypropylene mask between them, it would build up a static charge that was big enough that even at body temperature and humidity, you got the benefit of that for at least an hour. They didn’t show us data about what happened beyond the end of that hour. We don’t have information on how quickly that can cause a mask to break down because rubbing materials tends to cause them to break down faster. So that electrostatic component for home users I think is still an amazing, wonderful, fun theory, but the practicality of it still needs more consideration. But I think for instances where you’re going to go out for 15-30-60 minutes to run errands, and then you’re going to go back to your safe environment, it may be useful. More testing is needed. If you’re going to be wearing a mask for four hours, then that electrostatic boost you get isn’t likely to stay with the material the whole time. I looked at the data they have for the decay over time. It’s promising, but it needs more practical consideration.
Even without that electrostatic boost, the Q value for the nonwoven polypropylene is still the highest of all the others. The Q values that I mention in the summary are without the electrostatic charge. So that puts NWPP on the top of the list, cotton next, and then polyester somewhere in between. The nylon wasn’t breathable enough, so that’s why they voted no on that. The silk didn’t have enough filtration for them.
17. WHO Fabric Masks: Choosing Layering Combinations
Since early March, the very first thing I wanted to do was to get my mask designs tested. I did some basic hazard analysis to see if there were any obvious pitfalls because I wanted to make sure things were safe. There wasn’t any guidance on the ideal mask and what we should be aiming for in terms of testing criteria for fabric masks. The WHO guidance provides us some standards which we should be trying to adhere to in the design of our masks.
The WHO recommends at least three layers. A big part of that is adding that water-resistant, hydrophobic material to the outside. So, if you have a whole bunch of cotton masks and want to bring them up to WHO requirements, the only thing you need to do is add a mask cover of NWPP.
In terms of filtration, they say that for private masks for general use you should be aiming for 70% filtration efficiency. It’s nice to have some numbers there for what’s reasonable to get. For breathability, they suggest that you need less than a 40 Pascal pressure drop across the mask. That’s not easy for us to test at home. I have some data that I’ll share which shows that cotton masks and the cotton-NWPP combinations that we’re using do meet those criteria. For home users, I recommend putting your materials on the end of a toilet paper tube and blowing a ball of lint through them so you can test the breathability without having to put the mask up to your mouth and sucking air through it.
For the filtration, we don’t have access to the fancy equipment that the big testing labs do; we do, however, have access to our kitchens. For a lot of food stuffs, they have to calibrate the size of the particles. For those of you who both bake and sew, you know that having your baking soda and flour and baking powder at the right density makes a difference. Baking powder has particle sizes calibrated at less than 50 microns. You can find things in your kitchen with particle sizes down into some of the smaller-micron particles that are relevant. It can give you a sense of how well they’re doing. If I take the same toilet paper tube that I use for the breathability test and put it over the end of the material, for loosely-woven cottons you’ll see that the baking powder just shakes right through and makes a mess if you’re doing it on a piece of black paper. If you use a more tightly woven cotton, or two layers of it, or the NWPP, you can see that you don’t get as much going through. There are a bunch of other DIY home tests that people are looking at to try to get at that same small particle filtration.
Mask Care, Cleaning, and Disinfection
ETG: This is just the beginning of the conversation. We have questions about all kinds of other materials. We are going to be working with you if you’re willing to help people understand what these tests are and start to really think about the combination of fabrics that are out there as far as filtration, breathability and cost.
Songer: We’re designing fabric masks to be reusable and washable, and that’s a pretty big difference from what we’ve seen in the medical-grade masks. The WHO guidance references a French standard, which says that you need to make sure that your masks can hold up for at least five washes. That’s kind of a minimum for reusability. Then they suggest you need to be able to wash it at temperatures of at least 60C. I could give a whole talk on just the washing, cleaning and disinfection methods. The WHO and CDC recommend washing at the highest temperature you can. The WHO goes on to say that you can boil or steam combinations of cotton and NWPP. That’s important because that gets you a higher level of disinfection. COVID is somewhat sensitive to heat, so you don’t have to have the highest heat ever to kill COVID. But when you’re talking about a fabric mask that you’re putting over your mouth and reusing, COVID isn’t the only thing that can grow on that or accumulate on it. For some of the bacteria and fungi and spores, I’d like people to at least consider that you might want to periodically be killing off everything that could be growing in your mask and not just COVID. That’s something to keep in the back of your mind when you’re thinking about how you’re washing and cleaning things. When you’re putting things on your face multiple times, detergents become important as well. One of the biggest hazards with laundry in clinical settings is the buildup of detergent residues, which commonly causes skin allergies and irritation. So you want fragrance-free, low-residue detergents.
ETG: We have a question: Couldn’t you just wash the mask with hand soap for 20 seconds like you wash your hands? How is it different?
Songer: When you’re washing your hands, your skin is a fairly impermeable surface; water doesn’t absorb deeply into your skin. As you wash, what you’re mostly doing is rinsing everything off your hands and flushing it down the drain. When you’re dealing with cotton or any multilayer mask, you need to be making sure you’re getting at all the area that’s in those in-between layers and through all the seams and penetrating deeply through all that and anything that’s gathered in the pleats.
ETG: Can you iron polypropylene? Are you worried about that?
Songer: The short answer is you can iron it at the lowest setting on your iron; if you iron at a higher setting, it will melt. I have a Disinfection post on MakerMask where I went through the different temperatures that your iron gets to versus your drier versus your washing machine. The lowest temperature is probably fine, and there’ s a lot of data backing that up. The other caveat there is for the spunbond unwoven polypropylene. If there’s a mixture of other materials in there – polyethylene melts at boiling temperature. So if there’s any of that in the fabric, it’s going to melt and shrink even at the lowest temperature setting on the iron. So make sure it’s 100% polypropylene. The NWPP doesn’t shrink at all at 150F [?]. I tested five different cycles of steaming. With Polyethylene, it shrunk by 20%.
ETG: Could you spray the mask with alcohol spray? Is that going to do anything?
Songer: I vote washing, boiling or steaming. Whenever you start spraying chemicals onto it, you have to be real careful with residues and what you are then inhaling. Those solvents can also break down some materials more quickly. In general, I don’t recommend it.
A lot of people are getting little UV boxes to put their masks in to sterilize them and disinfect them. I don’t recommend that for masks. It’s good for materials that are hard and not porous, but masks have multiple layers. So the known challenge is that UV doesn’t penetrate through all the layers and all the seams. So in general, it’s not recommended because it can’t get to those middle layers.
ETG: You have a ton of this information and more on makermask.org.
18. MakerMask Breathability Testing
Songer: We’ve got some breathability testing on the webpage for a MakerMask cover which is a single layer of NWPP on top of an N95. We also tested the MakerMask Fit [inaudible:234:24] design and it has breathability showing that for less than five layers of NWPP that works out. Then the data we have showing the NWPP and cotton combinations: I’ve got a picture of a whole bunch of MakerMask Surge designs as well as some of the Craft Passion designs looking at the breathability for three layers of NWPP, three layers of quilting cotton and then combinations of NWPP and cotton. We haven’t managed to get that data published yet, but all of those combinations were breathable. So this reinforces that you can do your two layers of cotton and a layer of NWPP on the outside. The filtration meets the WHO standards with those combinations as well.
19. Thank You
Question and Answer Session
Participants: Dr. Jocelyn Songer, Dr. Elizabeth Townsend Gard, and Joel Sellers
Joel Sellers: We made 25 different combinations. What it really helped with was looking at what was easier to sew. The slippery stuff was all hard to sew, especially when you do it quickly. The two and three layers of polypropylene were tough on the needle. It’s heavy-duty stuff.
Songer: We have a needle recommendation up on the website of 16.
Sellers: I think it may even be an 18. We ordered a bunch of fabric any time we saw polypropylene. Some of them were woven; some were solar.
Songer: A lot of those have UV coatings on them, so that’s another flag.
Sellers: We got a lot of this stuff through Jo-Ann’s, and it had all the information about it. So you’re thinking this may have chemicals that are probably not the best thing.
Songer: Yeah. So a site that often gives that information is SailRite, which I’ve used when I make source materials for outdoor gear. I know that they have one of the lighter-weight polypropylenes. I haven’t ordered from them yet.
Sellers: One of the easiest and least expensive was the Pellon 915. It’s a non-woven, non-iron-on Pellon. It was less than $2 a yard. It sewed very easily; it was very breathable; very comfortable. What I wasn’t sure about was durability. We put some sort of quilting cotton on the inside of all of them except those that wanted just two layers of silk or satin. That was for comfort; I can’t wear that scratchy stuff next to my face.
ETG: Is the thinness a problem? We could put two or three layers of it. Is that better than thickness in terms of polypropylene?
Songer: The thicker stuff tends to hold up better and longer. If you’re putting it through the washing machine, I recommend putting it in lingerie bags. I tend to like to do an outer layer that’s one of the heavier ones, but what the WHO study and guidance show is that one of the nice things about the lighter-weight polypropylenes is that you can layer them and keep the same Q value. They specifically talk about interfacing. The material they’re using is I believe 30 GSM, which has a really high Q value so it’s good for filtration and particle filtration. They added five layers of interfacing at 30 GSM each, so that’s 150 GSM, essentially. It’s still lighter weight than a lot of other materials.
Sellers: Someone thought this was polyester, and many interfacings are, but Pellon 915 is polypropylene.
ETG: We can find out what the GSM of it is.
Songer: That’s something we can test at home, which is really useful in having conversations between sewists and scientists. You can get a kitchen skill which will measure 5 grams or less. So you take your square of fabric and see how much it weighs for a given area – either ounces per yard square or grams per meter square. Then we can at least have one of the parameters the same between us.
ETG: What’s the goal on grams to get to?
Songer: They don’t give you a goal in grams to get to. They were trying to get a certain total particle efficiency. They know from the Q value that you can layer it together and get the same ratio of filtration to breathability. To get 70% particle efficiency, you stack the layers. The more layers you stack, the more filtration you get.
ETG: You could easily do five layers with the Pellon.
Sellers: I can certainly try it. Trying to make the pleats is a little bit tricky when you have lots and lots of layers and it’s very heavy.
Songer: I’ve made a few with five layers of a 40 GSM material. That’s less thick than a shopping bag at three layers, and it is the most breathable mask I’ve tried so I’m really excited. I sent it off to get particle testing done on it. I don’t know if it will make it through five wash cycles and how the properties change over time with washing. We may be able to help solve this together if we can get coordinated so we’re doing the same sort of home experiments and sharing data with each other. There are a lot of us.
Sellers: This one is two layers of shopping bag and one layer of quilting cotton, and it’s really not a problem. It’s fairly easy to wear; it wasn’t bad to sew. Our comment was that our cotton masks are so much prettier, but that’s a minor detail.
Songer: We say it’s a minor detail, but humans are social creatures and we like to have flare and ways to express ourselves. As an engineer, I just want it to be functional; I don’t need it to be beautiful. I can select different colors; what more can you ask for? But my mom gets that extra flare in there with the cloth ties. And if you have a cloth material inside a cotton with a pattern that you like, and you roll it into the nosepiece rather than out, then you get color across the top and the bottom.
Sellers: We made some using silk and chiffon, and as always you’ve got to pin the heck out of them because they’re slippery.
Songer: The only way I could make silk work was hand-sewing it. So I have some that are two layers of NWPP with silk on the inside instead of cotton, which meets the WHO criteria. The silk and NWPP generate their own electricity. I don’t think it’s enough of an effect for it to be meaningful, but in dry conditions it works. It’s soft and comfortable, but I find that the silk is also warm. For me, both the silk and the cotton end up feeling warm because they’re absorbent and trapping that moisture by my face. It feels really nice when I first put it on and it’s cold out and I’m not worried about being active.
Sellers: We did some flannel masks in the winter, which we will never wear down here. The quilted one, I just quilted a couple inexpensive pieces of fabric. But I wasn’t sure why…
Songer: The rationale there is in both commercial masks and the WHO guidance, they ask you to put a nonwoven layer in the middle because it does well for the particle filtration, and that remains true. It’s just you then have a 2-3-inch…
Sellers: There are the two-part patterns with the seam down the center that is more fitted around the face versus the rectangular with the pleats. Does that make a difference?
Songer: The standard that the WHO references, which is the French Standardization Association, they have strong feelings about that. They say you should not have any vertical seams in the middle of it. Because if you’re concerned about all the particles that may or may not be going back and forth, having a seam going straight up through the middle in the center of the mask has holes from the needle. That’s one of the advantages of pleated masks is you don’t have a seam line up the middle. As an outdoors person, I have a lot of experience doing waterproof seams, so it is possible. But if you do have a seam up the middle, you would want to make sure that things aren’t leaking straight through it.
So the quick home test I do – I’m using water-resistant material so that makes it easier – is I go to the sink and I see if there’s water dripping through the seams. That’s not nearly as small as the 0.3 micron particles that higher-level masks get tested with, but that’s the concern there is that you’re losing efficiency by having holes going up the middle. Waterproof seams aren’t well tested yet for facemasks.
ETG: We really want to keep working with you. There’s a ton of people that are asking a thousand questions. Really, the goal is to take all these questions and the samples and think through all these things and put out something that is really made for the sewing community. It’s really important for us to know these things.
Songer: I should have met you at the beginning, too. I’m an engineer, and I’ve done the research and the science. But being able to communicate something as an engineer to other engineers is different than being able to communicate with sewists.
ETG: One more question: These masks seem to protect me a bit more. Am I right about that? I think that’s a good message that we should be getting out there that it isn’t just about…
Songer: It may act as a bit of a barrier. We don’t have the science to prove that it can protect the user. But I designed it with that in mind. I didn’t want bodily fluids to go from one side of the mask to the other side, so that’s why I focused on those water-resistant materials. I was used to thinking about you get blood or spit or anything on a mask that’s an absorbent material, then you end up with it on your face on the other side.
ETG: We have engineers and textile scientists and chemists listening. This is Becky: “I’m an engineer and a sewist and we’ll get the info out. You have got a team behind you that love you and are so excited that you’re here.”
Songer: If we can develop things together, there’s so much we can do to get things tested and make things better. Masks are better than no masks, but that shouldn’t prevent us from continuing to work to be better. For this pandemic, droplet precautions and droplet protection is working, which is awesome. And we see how far we’d have to go from where we are for something that does better at particles. There’s so many things for us to get better at, especially testing. That’s exciting and sometimes daunting and overwhelming.
ETG: This is the beginning of one conversation. We have everybody’s email; we’re going to connect to people. We will work with you. We love you. Thank you so much for your time.
Songer: Thank you, thank you, thank you to everybody who’s been pouring their hearts and souls into making masks and getting them out there. Data now shows that we are making a difference, and as more data comes out hopefully we’ll be able to get better and better.
ETG: Can we put little pieces of polypropylene in all those filter areas and just sew it back up on all the ones we’ve made? I know it’s going to have cotton on the outside, but we’ve just got a lot of these already made with holes in them.
Songer: I’m okay with that.
ETG: We’ve got a lot with filters in the middle, so we’ve got to figure out how to adapt those. And then going forward, we’ll do the polypropylene on the outside and cotton on the inside. But we’ve made hundreds of thousands of these.
Songer: I know. We need numbers on that.
ETG: We’re going to work on that. We will be in touch with you. Thank you! We all love you!
Homemade Mask Guide
At the Completion of the Homemade Mask Summit, the Homemade Mask Guide was created as a collaborative effort between sewists and scientists from JustWannaQuilt.com, MakerMask.org, WeHaveMasks.org, and The Newcomb Institute, Tulane Univeristy. Check it out below:
Just Wanna Quilt Podcast: COVID-19 Masks with Dr. Songer (June 15, 2020)
Transcript: Covid-19 Masks: Dr. Jocelyn Songer of MaskMaker.org joins us – Part 1
June 15, 2020
Transcript edited for brevity/clarity.
Participants: Dr Elizabeth Townsend Gard, Dr. Jocelyn Songer, Whitney, and Alexa
Elizabeth Townsend Gard (ETG), Host: We had a delightful evening with Dr. Jocelyn Songer. She is the founder of MakerMask.org and also a biomedical engineer. She has outdoor experience with backpacking and emergency services and breathing. She has been testing masks and has a strong belief as to what material we should be using for masks. We went for an hour, and then we decided we needed to chat more and chatted for another hour and a half.
So this is part 1 of 2 of a very long, in-depth conversation with Dr. Songer. She is going to be our keynote speaker for our Home-Made Mask Virtual Summit this coming week.
Opening Questions: Dr. Songer’s Background
Dr. Jocelyn Songer (JS): I’m Dr. Jocelyn Songer, and I’m calling from Orange, MA.
ETG: Awesome. We ask everybody this question: Do you have any memory of anyone sewing or quilting in your life? If so, what?
JS: Absolutely. Both my mother and my grandmother sew; my grandmother was a seamstress. She would look after me, and I pestered her forever to let me use the sewing machine, which at eight years old probably was never going to happen. But she did let me use a needle, and she and I did work together to make dolls. She helped me make little patterns, and we would go back to the drawing board a zillion times. But eventually she’d kind of zip one together and then let me do the stitching work. So I have lots of fond memories.
ETG: So what was your life like November, December, six months ago?
JS: Six months ago I was balancing my work on neuromodulation and neuro/biomedical engineering with backpacking.
ETG: Tell us a little more about both. Tell us what that is and a little bit about your path of how you got there.
JS: So my background is biomedical engineering and electrical engineering, and I’ve always been passionate about health and helping other people. I’ve maintained certifications as a first responder. I’m very geeky; I have a very science and engineering mind, so I’ve applied my energies towards developing innovative clinical tools for diagnostics and treatment.
ETG: Very cool. Give us some examples so we can have a concrete understanding.
JS: A lot of the work that I’ve done has been on hearing and balance in the inner ear. So understanding how a hole in your ear can make you lose balance.
ETG: How did you get to that? How did you want to be doing that?
JS: When I was young, I loved health and science. My mom is a nurse, so I was passionate about that. I saw a talk on the brain, and what is cooler than how the brain interfaces with electronics and electrical devices. So that is what nudged me in that direction. Early in my career, I got interested in the ear and the acoustics of sound because cochlear implants was where the brain met electronics the best. Then there were some real-world clinical challenges people were finding where this hearing and balance stuff was interacting. So I studied acoustics of sound and how it’s produced and how you hear it, and that kind of led me into the brain.
ETG: Very interesting. So you’re going along; you’re backpacking; it’s great. Then what happens?
JS: So I am asthmatic, so I have to pay really close attention to when there are respiratory illnesses getting big. I flew to a conference in January and was already concerned about COVID so I had masks that I was bringing with me. I’ve hiked across the US three times now, so I’ve had to have masks with me at all times or to be able to make DIY masks as needed because of forest fire smoke. So hiking across California, New Mexico, Oregon, Washington, Colorado, Montana where there are forest fires 24-7, and you can’t get away from it because you don’t have a house; you don’t have shelter; you don’t have running water. So you have to figure out how you’re going to make traditional and nontraditional solutions come together so you can breathe. For me, breathing is a privilege. Most people don’t think about it very often because they can just do it, but since 2009 I haven’t been able to take breathing for granted.
ETG: Me either. I had a couple of pulmonary embolisms and they didn’t go away. So yeah, not breathing is really awful. If you’ve experienced not breathing, it sucks – gasping trying to get air into your body is not fun.
JS: It changed the whole way I had to interact with the world. I had occupational asthma. I was literally allergic to my job, so my whole life kind of shifted.
ETG: What was your job that was causing that?
JS: I was doing research in a facility that had fuzzy, furry critters, and I became allergic to them over the course of five years. It happens to about 80% of people, and I was from a small subset that went on to develop asthma. But as a vet, I have all this background and real-world experience in particles and what size they are and how they disburse in travel because I wasn’t the one working with the fuzzy, furry critters I was most allergic to but certain sizes of particles travel and distribute more. I had worn an N95 daily for occupational work, so I had some real experience with how they are not always the most fun things to wear or the most comfortable. Similarly, I hiked with N95’s in the desert – reusable ones while I was backpacking. So I watch TV now and I see all these people with masks that are worn improperly just covering the mouth and not the nose, and I’m like: “Oh, I so understand that…”
ETG: It’s too exhausting; it’s awful.
JS: It’s too exhausting, and it can be uncomfortable. So you kind of shift it; in the desert I did that with the smoke because I would be hot and sweaty but I needed something, and it helped. It sort of highlights some of the differences between when you’re wearing a mask for infection control, essentially in a pandemic where the things that you do to treat with forest fire smoke or other things where you’re like, “well, if it’s preventing me from breathing through my mouth, but all that stuff is coming out of your nose…” So every time I see it on TV, I’m like: “if you can’t wear the mask…” The most important thing about a mask is your willingness and ability to wear it when you need to be wearing it. So if it’s an N95 and it isn’t perfect, that’s okay if it’s a mask that you’re willing and able to wear for the amount of time that you need to wear it.
So I feel like some of those human factors are things that don’t get talked about very much. I make my masks, and I know the science really well, which helps. I have experience as a first responder, so I’m used to thinking about these things.
ETG: So we’ve been doing research; we’ve been talking to different people: industrial hygienists and all kinds of other people. We’ve learned about big particles and tiny particles and electrostatic fabric versus cotton and all this stuff that tells us where we’re at.
For those that want to follow along, go to makermask.org.
You’ve got a science-based resource on creating masks. We’re doing a summit next week, and the goal is to gather everything. There’s so much science out there, and we really want to be able to make masks for our friends and family and communities – first responders if they need them again. But there’s too much science out there; it’s chaotic. So tell us about your science. You design water-resistant, non-woven, polypropylene. We just got some polypropylene that’s latex-free and can be machine-washable or disinfected by boiling or autoclaving. So tell us what that is and why that’s important and how you make your masks.
JS: I initially started from the infection control standpoint. What we know most about COVID-19 and the transmission of SARS-COV-2 — which is the virus associated with it – is that it’s mostly transmitted through droplets. There’s a whole long dialog about the different forms of transmission, but for droplets in hospital settings, it means that they wear surgical masks, gloves and gowns. The surgical masks in those cases provide droplet protection, which means they prevent water-based droplets from coming through and those masks are water-resistant. So they’re designed to block bigger particles and especially particles that are in water. That’s why I started looking for water-resistant materials is to block droplets so that you can contain your droplets to you and keep other droplets out.
ETG: It’s a great website because you’re also suggesting what is polypropylene on there, right?
JS: Yeah. I was used to thinking about polypropylene from backpacking because all of these synthetic fabrics and high-tech materials are really popular there. But most of those materials are woven, so the big stuff goes right through it. The challenge is finding something that’s water-resistant so it provides a barrier to droplets; that’s breathable; and that you can wash, clean, sterilize, disinfect. So you have to have the trifecta there. Reusable grocery bags are nonwoven polypropylene. It’s really hard to talk about because people are like: “I’m not going to put a bag over my head!” Absolutely, don’t put a bag over your head. The key is it’s got to be breathable; if it’s not breathable, don’t use it. That’s rule number one.
It turns out that these reusable, nonwoven polypropylene bags, which I shorten to NWPP, are designed to be touching food, which is good because they meet some standards; they’re designed to be washable so they can be disinfected; and it’s water-resistant because you don’t want the wet stuff from your food soaking into the bag. So it met all those criteria, so that’s how I ended at nonwoven polypropylene from reusable bags. It’s because of that food-grade component that made me select that relative to other things. It feels like fabric, and you can find it in all sorts of sources around the house like with the food grade but in other things like interfacing, which sewists are much more familiar with. There are lots of variations, but you can get nonwoven polypropylene in interfacing. The caution there is that most of the interfacing that people are used to is fusing interfacing.
ETG: Right, so you want non-fusible?
JS: Right, because fusible has adhesives. Breathing in adhesives is usually bad.
ETG: And stabilizer? They have stabilizer that’s not fusible.
JS: Some of the stabilizer if it’s backing that’s tear-away for some embroidery projects, a lot of that is also nonwoven polypropylene. They’re different weights. I feel like I’ve been down the rabbit hole on nonwoven polypropylene and looking at all the different kinds with different safety and engineering features because when you’re making something, you want to make sure you’re not doing more harm than good.
Whitney: I think that’s why we’re trying to do the summit is because there are so many sewists and quilters out there who want to help and make masks, but there’s so much information and some of it’s conflicting, and it’s like what do we do because we just want to do the best thing.
JS: I want people to wear the masks that they’re going to be comfortable with and that they can get or create. A lot of people have been focused on making a zillion masks and getting them out as quick as possible. As a scientist, engineer and researcher, the thing I can do is take a deep dive on all the science and come at it from the health perspective, too. But there’s so much information that figuring out how to communicate it to people who are sewing masks, wherever they are, more effectively is the thing I struggle with.
ETG examined some nonwoven stabilizer.
JS: The polypropylene in particular that I’m looking for is called spunbond. That gets into the details of how it’s made. But if you look closely at the bags, they have this little pattern to them that looks almost woven.
ETG: This one is flat.
JS: I think what you’ll find is that if you go to tear it, it tears more easily than if you had some of this other stuff.
ETG: This tears really easily. You want it to tear easily, or you don’t?
JS: You don’t want it to tear easily. If it tears easily, it’s not going to hold up as well to washing.
ETG: So for single use, it would be okay. It’s just the washing factor that you’re concerned about, is that right?
JS: Right, the durability. If you’re going to wash it and try to disinfect it to use it multiple times – especially if you’re putting it in the middle layer of a mask, you don’t know how it’s holding up.
ETG: So you just want the basic one that doesn’t have any extra bells and whistles.
JS: Right. If you’re on the webpage, there’s a section called Research Blog. If you page down in there, there’s a place called Big Four: Criteria for Community… That one dives into all of that…
ETG: Tell me a little bit about the fluid resistant test.
JS: In the US, for something to be called a surgical mask, it has to be fluid resistant. The FDA has really strict conditions for what that means. There’s one specific test that it has to pass which uses synthetic blood. That’s for surgical mask classification. Most of us who are just trying to make masks for community use for friends and family, water resistant is much more easy to check at home to see if it’s going to provide some barrier to water. The simplest version is you just flick water at it and see if it beads up on the surface. If it beads up on the surface, it’s hydrophobic and water resistant, and if it absorbs into it, it’s not; it’s hydrophilic. With the mason jars, you can measure it and quantify it, which makes the scientist in me really happy.
Mask Designs and Layers
ETG: Let’s go back to the masks that you’re making. You have Cover, Surge and Fit. Let’s talk about Surge and Fit because Cover is the N95, and that’s not really where we’re at I don’t think.
JS: Although I’ll mention that WHO has released new guidance on fabric masks. Three layers, including nonwoven polypropylene.
ETG: It’s like they knew you.
JS: One of the things with the Cover is that you could use it over cotton masks if you wanted to have a layer of water resistant over materials that are more water absorbent.
ETG: So, the Surge is the pleaded masks a lot of people have been making. It’s got three layers, and it’s got the pipe cleaner across the top so you can fit it. Do pipe cleaners wash okay?
JS: If you sew them in, they’ve been rewashing fine. It’s on the Surge guidance as two; I find it works better with three because it makes it a little bit stiffer and you get a better fit.
ETG: Three together?
JS: Yeah, I push them together. What I’ve found I love to put in the nose pieces are the ties that go around coffee bags. There are a number of different things you can use to stiffen across the nose as long as it fits.
JS: I forgot to mention that when I wash the ones with pipe cleaners or any other nose bridge, I put them in a lingerie bag because otherwise they get bent a lot.
ETG: So you’re doing three layers and they’re all polypropylene. You’re not doing a cotton layer. How do you feel about cotton?
JS: The nice thing about cotton is everybody has it. For all these other materials, we’ve had challenges sourcing them. Initially, the masks that you could get people wearing as quickly as possible were the best. Cotton tends to be absorbent.
ETG: Which is bad…
JS: I think absorbent is bad for the outer layer of the mask because what I want to do is make sure that I have a water-resistant layer that isn’t going to…
ETG: So one polypropylene layer on the outside.
JS: Yeah, at least one polypropylene layer on the outside. That way if anything with moisture comes at you, it can shed and fall off, and your droplets don’t spread beyond the other side.
ETG: How do you feel about cotton on the inside?
JS: I’m okay with cotton on the inside (against the face). It’s more comfortable for a lot of people because they’re used to it. It absorbs the moisture so it kind of keeps it close to you. If people are worried about the synthetics touching their skin, cotton is good. I still recommend and prefer the nonwoven for all three layers. Part of that gets into the washing and cleaning and drying aspect. Nonwovens dry faster, whether it’s from your own moisture or from washing. It dries really quickly, so that’s less time that you have a warm, moist environment for things to grow in it. So I prefer using different weights of nonwoven polypropylene for the different layers. The default instructions say use three of the same because up until now we haven’t had a lot of variety in where we can get nonwoven polypropylene materials. So if you only have the bags, you can use that for all three. That is not as comfortable as the nonwoven polypropylene in garment bags and other sources. The inner-most layer of the mask for me is mostly about fit and comfort. I rely on those other layers to provide the barrier and filtration and all those other features and factors. I increase the number of layers if I want more particle protection.
ETG: How far do you go?
JS: The very first thing that I did after developing the masks, designing them and proposing them and researching the heck out of them was send them down to ATOR Labs in Florida to get breathability testing done on them. I have been searching for all the other testing ever since. Where I haven’t been able to get professional testing done, I’ve come up with DIY procedures to test all the critical elements. For the professional lab testing, we got ATOR Labs to work with us, and they provided breathability testing: inhalation resistance, exhalation resistance, CO2 accumulation, for all of our mask designs.
ETG: How did it go?
JS: It went well. That was what slowed the initial – I wasn’t willing to put this stuff out there until I had seen that it was at least breathable. We’ve looked at the safety data sheets, and we’ve thought about different potential hazards, and we’re confident that we’re not going to do more harm than good. I tested up to five layers of the NWPP, and they passed the breathability criteria. They also pass the French standard referenced by the WHO. I’ve got some of that data up on the webpage, though I haven’t been able to get it all written up.
ETG: Tell me about fit because we’ve heard that the fit is really important; if it doesn’t fit right, the percentage of protecting goes down real fast. What are your thoughts about that?
JS: The challenge here is you have to know what it is that you want your mask to do for you. Masks are like shoes: sometimes you wear sandals, sometimes you wear sneakers, and sometimes you wear mountaineering boots. You wear them to do different things, and the same shoe doesn’t fit everybody.
ETG: We saw with the Olson masks and these other masks that are flat, they didn’t fit very well and you had to have the right face and the right mask. So we went back to surgical because we didn’t know who was going to be wearing them. We wanted my husband who has a big head and my daughter who has a small head to both fit.
Filter Pocket? Yes or No
ETG: I’m curious what your thoughts are on the whole filter pocket thing.
JS: That ties into the fit of the mask in terms of acoustics and airflow. Essentially, the air is going to follow the easiest path. So if you have a really good filter in the middle of the mask and it doesn’t go all the way to the edges of it, the air is just going to go out and through the edges. And if it doesn’t fit well on your face, the air is just going to go out the sides or up through the nose around the eyes. The nose piece is super important in that respect because if you don’t have that nose piece, the air is preferentially going to be going in and out through the space by your eyes. Pulling all the air you’re breathing past your eyes is a bad idea for infection control. All these people show these videos of them with a mask on and trying to blow out a candle, and they’re really excited because they can’t blow out the candle with the mask on. I just do a facepalm on that because I can watch the air going out the sides as they breathe because now the air is going through the mask. So if the air isn’t going through the mask, where is it going? What it means is it’s found an easier path out the sides or down the bottom or around the eyes.
ETG: So do the polypropylene ones allow the air to go in and out and not the particles? Is that the idea that it’s keeping the little particles out but the air back and forth in and out?
JS: Right, and the water out. Because the droplets contain the particles, if you’re keeping those droplets out and you have water resistant, you’re keeping the water out but allowing the air to go through. That’s your balancing act. Same thing with particles: Keeping the particles out, allowing the air to go through.
Ear Loops or Head Ties
ETG: You’re using straps and not elastic. We did, too, because it’s a better fit. The elastic was a chaotic mess in our house with big head, little head. But the straps work really well.
JS: and you can individualize straps as well so you can adjust for different head sizes. And elastic stretches, so as your face moves, the mask moves and shifts. Having the ties helps prevent that. The other issue is latex; most elastic you get contains latex. The first reason why we moved away from using elastic was because so many people in healthcare settings have latex allergies.
One of the challenges with all these masks from alternatively-sourced materials is that if you say “cotton” that describes a huge range of things; same thing for polypropylene.
ETG: There was a study that came out. They went to Joanne’s and Wal-Mart, which is totally weird. From a sewing point of view, there was not enough specificity for us to really be able to use it. This whole thing with electrostatic, man-made fabric, cotton – how do you feel about all that?
JS: I agree. One of the challenges with all our mask-making efforts regardless of which materials you’re using is standardizing so you know the material you’re using is the same as the neighbor down the street and if the guidance is applicable and useful.
ETG: I was so frustrated with the dataset.
JS: Part of that is because the scientists are doing what everybody else is doing, which is finding the materials they have now available at home.
ETG: I felt like there was a discourse disconnect. Why aren’t you asking the sewists? We could tell you. They found a flannel that had a percentage of – it wasn’t a 100% cotton flannel, but we all have 100% cotton flannel. Try to find one that has some percentage of a man-made thing, that’s bad flannel!
JS: As a backpacker, I’ve done a whole bunch of research into fabrics and materials to make my own gear. So I have a stack of all these high-tech fabrics that are ultra-light and water resistant and wind-proof and all these different things. That gets you into the language people use to describe fabrics. That is a real challenge. How do I translate thread count to grams per square meter? I translate everything to GSM because that’s at least a thing I can weigh at home and test and verify where my 400 thread count and your 400 thread count are still…
ETG: The New York Times Article said “batik.” So we bought a bunch of batik and we used it, but we want a little more science in the material for us.
Balancing Material Properties
JS: I think that’s a great dialog to have, though, because the important features are the weave, thread count or fiber density, and the GSM is a weight that at least allows you to normalize things. There are some studies that say denim is great, but they put a little asterisk next to it and say that you can’t breathe through it. But the take-home message is that denim is the best mask material. But if you can’t breathe through it, it’s useless.
ETG: We had a study come out that said one layer cotton and one layer flannel. So we made these, and we sent them out, and we’re in New Orleans; people are like, “you’re trying to kill us!” There’s no way you can have flannel in the South in the summer.
JS: There’s a scale. If what you’re trying to do is get N95, the best technologies in the world for N95s are coming out of 3M, and most people who have to wear them hate them. They wear them for as short a period as they can because they’re hot, humid, and they’re not comfortable. That’s as good as you can get when you’re pouring a lot of resources into this one thing. But to get an N95 that gives you the particle filtration that’s been the focus of the conversation so that you’re blocking 0.1 micron, it is not very breathable, not very comfortable. Most people are not going to wear it well for more than 10-15 minutes before they pull it down or take it off. As soon as they do that, they’re getting 0% particle filtration. So who’s going to wear it? Where are they going to wear it? And how long are they going to wear it? And what’s the relative risk? For a really high-risk environment, you should wear more layers to give you the best particle filtration you can get. I use three layers of NWPP when I go to the grocery store. I have some that’s thicker that gives me a higher degree of protection, but I don’t want to wear that very long. When I go hiking or into the Maker Space that I’ve been helping out, I wear something that’s a little bit more breathable because I can wear that for four hours straight without taking it off and without touching it to readjust it.
ETG: There’s a whole list with chiffon silk, 100% polyester… What are we supposed to do with that? Do we add two layers outside, inside? Are we really spending $40 a yard on 100% silk? Is that better than polyester silk?
JS: It is very different, certainly. When you’re mixing and matching fabrics, the first thing I would say is to make sure that the washing instructions are going to work for all of them. Also, in terms of how it wears out, you that sew a lot, you know along the seams if you sew your chiffon to your canvas denim…
ETG: It’s going to pull out if you’re not careful. The weight differential is going to mess it up.
JS: When people are going down these rabbit holes on chiffon versus silk and not giving us any information about which of those materials they’re specifically talking about, a lot of that is thinking about that really fine filtration.
EGT: They’re trying to do the electrostatic for the teeny-tiny drops. That’s how you keep them from getting in.
JS: That’s how you get better particle filtration while still keeping breathability.
ETG: And how do you feel about that?
JS: I feel like it’s a challenging thing that’s still very experimental. For me, it worked well because NWPP holds a charge very well like other synthetics. A study that just came out June 2 is like yay, not only do you have your filtration for lower weight and more breathable materials – 43 GSM interfacing in particular – I think that’s kind of light weight. It doesn’t hold up as well. The WHO guidance specifically says non-woven polypropylene interfacing is a good material to use. That’s based on this paper I was just mentioning which shows the particle filtration, and they show that hydrophobic materials are able to store a charge on them which cotton can’t, and unlike other materials like silk, they keep charge for a longer time. It holds a charge overnight at room temperature. They tested it at body temperature and high humidity and found that it held a charge for at least an hour, which is pretty good. That’s where the guidance for using synthetic layers like nonwoven polypropylene and polyester are coming from. If you roll them between your latex gloves and build up a charge and you do that for 30 seconds, it builds up a charge that can last an hour even in humid conditions to give you a bit of a boost on the filtration. That’s interesting and exciting. We’ll take extra boosts if we can get them. It’s specific for hydrophobic materials because if it absorbs water, it doesn’t keep the static charge.
We don’t know how that kind of treatment is going to impact the durability for reusable masks. If you’re sitting there and rubbing the heck out of it for 30 seconds every time you wear it, that’s going to break it down faster. So like many other things, there’s a trade-off there. I’m curious to see how that pans out over time.
ETG: So on Amazon we’re looking for: non-woven interfacing polypropylene, breathable, dust-proof, anti-fog. Then it’s got one that’s waterproof and one that’s not.
JS: So waterproof and breathable don’t tend to go well together. When I think waterproof, I think Saran wrap. It’s waterproof; it does a great job at blocking particles; but don’t put it over your face; it is not breathable. The most important feature of your mask is that it’s breathable and not hazardous.
ETG: People have made a ton of cotton masks; most shops are selling those, too. We may not be making them in the crazy way we were; it got political; companies are making them; people think they don’t need to wear them. I don’t feel that way.
JS: And also burnout. I just want to say to all the people who have been sewing hundreds, thousands, no matter how many, I have seen the most heartening thing while the whole world is falling into chaos for so many reasons. I agree that spending 103 hours a week on masks for months at a time isn’t sustainable.
ETG: It was really exhausting. So going forward, polypropylene is going to be hard for people to get, I imagine. What are your thoughts about a layer or two layers of polypropylene plus cotton plus chiffon. If people are out there freaking out because they have all this cotton but no polypropylene, what do we say?
JS: I would say that the best mask is a mask that you can have, you can get, you can make. So I don’t think we should throw out these other masks. We know the science is evolving rapidly around us. For a long time, my thought is if you have some nonwoven polypropylene, if you can just make a layer of it to wear over cotton masks so you get that water-resistant, hydrophobic layer on the outside…
Mask Layering Combinations
ETG: So the outside is key. You wouldn’t want cotton and then polypropylene; you want the polypropylene on the outside?
JS: I want the polypropylene on the outside, absolutely. I think two layers of cotton inside, one polypropylene outside or one cotton, two nonwoven polypropylene; all those are fine. I would advise against the cotton sandwich where you have a water-resistant, non-woven polypropylene with cotton or some other absorbent material in the middle and then NWPP on the other side because of washing and disinfection. If you’re trying to wash something, and you trap all this warm gunky stuff in the middle, how do you make sure that is getting clean when you have two water-resistant layers on the outside? That may be fine for a disposable mask, but for anything reusable, that’s the sort of thing that absolutely needs validated disinfection and cleaning methods because that scares me in terms of what might grow in the middle.
ETG: Can you do the opposite with cotton on the outside but the polypropylene on the inside?
JS: I think that’s okay. I wouldn’t consider it ideal because anything coming from the outside is going to get trapped in that absorbent layer, and you’re holding it closer to the face. That’s the thing that I dislike about that. But you do still have that water-resistant layer in the middle that’s acting as a barrier to hopefully help keep things from going out or going in. But I have to note that the WHO and the CDC and all the guidance out there right now says that you should be using masks for source control. The only thing you’re concerned about is keeping your germs from going out.
ETG: That’s any cotton mask, then, on that level is okay.
JS: Yeah. Some of them are going to be better than others. That’s why they all say use multiple layers because one layer acts as a diffuser potentially; that gets into a longer discussion. But for what the government and regulatory officials say we should be doing, having just that nonwoven layer in the middle serves that purpose; it helps keep your droplets to you and the other droplets going the other way. If you have an absorbent layer on the outside catching everything that’s being thrown at you, and then it’s drying out, once it’s dried out it’s a smaller particle size. So I don’t recommend having an absorbent layer on the outside. There isn’t any science that I’m aware of yet that backs up my intuition and my view and analysis of why that’s concerning.
ETG: You think three layers of NWPP is the best, but if you have the masks that don’t have that, it’s okay; it’s better than nothing. And if you’re trying to do a hybrid, that’s not super key.
JS: Pretty much. I will say that in terms of what that layer is closest to the skin, I’m not sure. Having that be cotton like the WHO recommends may be just as good as having it be all three NWPP. I find it less comfortable and too warm. There are a lot of reasons why I recommend that three layer. Part of it gets into washing and disinfection.
Washing & Disinfection
JS: There’s a whole blog post that goes into way more scientific detail on that. If you have a mixture of materials and fabrics, especially the absorbent ones, when you wash them with detergent you can get skin irritation.
ETG: You have to use detergents that support allergy return. Fragrance free.
JS: The EPA has a whole site that goes into detail. But if you’re going to use detergents, keep that in mind because you’re holding things up against your face for a long period of time in hot, moist environments.
Transcript: Covid-19 Masks: Dr. Jocelyn Songer of MaskMaker.org joins us – Part 2
June 15, 2020
Transcript edited for brevity/clarity.
Participants: Dr Elizabeth Townsend Gard, Dr. Jocelyn Songer, Whitney, and Alexa
Elizabeth Townsend Gard, Host: Let’s start with you and what you really want quilters to know as a scientists coming into this as someone who cares and has breathing issues yourself. What should we understand?
Dr. Jocelyn Songer: I think the first thing is how much we appreciate you, because all of these efforts to get masks to as many people as we can as quickly as we can would not be happening without you.
Second is that even though it’s complicated, it’s worthwhile. Keeping breathability in mind is always an important thing because we’re covering the mouth and nose. We want to do that as safely as we can. So it has to be breathable, and it has to be something that people are willing to wear for the entire time they need to be wearing it.
In terms of the science, ask questions. As long as you keep asking questions, it will force people to come up with better answers. We’re all in this together. We’re all working to create better solutions to make our families, friends, community and healthcare providers safer. We’re doing an amazing job at that even if things may not be perfect yet. Don’t let perfect be the enemy of the good.
Alexa Magyari, Host:
We’ve made all these masks. You’ve proposed a couple solutions in Part 1; one if to make a nonwoven polypropylene cover to go over a cotton mask that we’ve made. You’re suggesting that this is superior to making nonwoven poly propylene (NWPP) filters to put in the filter slot?
JS: I would say yes.
AM: Would you say that making those filters is better than nothing?
AM: Do you have any other insights into how to modify these cotton masks that we’ve already made to improve them?
JS: What I would do is if you can put one layer of NWPP and have that go over it, that will give you that extra water-resistant boost. A lot of NWPP is pretty lightweight, and one of the advantages is that it’s really breathable. So you can put a layer of it over an N95. N95’s are not the most breathable or comfortable things in the world, and it’s still breathable. We tested that, and it got a big thumbs up.
AM: So we know how we’re going to fix our imperfect masks of the past if we’re so inclined. Moving forward, the gold standard in your opinion is the three-layer NWPP. In an ideal scenario, where are we sourcing that material?
JS: That is the big challenge. The ideal material in an ideal world is medical-grade spunbond nonwoven polypropylene. There isn’t a great, easily-accessible source for that yet. We’ve got people working on that and trying to coordinate with distributors. But moving forward, that’s what we would like to do is to make it so that as this continues, there’s a place that we can point to where mask makers can obtain materials that we’ve tested and know are great.
AM: In the absence of being able to buy it in bulk, is the best thing to do to cut up my bags? Or is it better to start with the interfacing?
JS: I haven’t been using the interfacing, so I can’t personally attest to how well that works. But if it’s a separate layer, you can test that out on your own; see if it’s water resistant; see how it holds up as it gets washed. I recommend boiling or steaming to disinfect.
The reason why I suggested the reusable grocery bags if they’re unused is because if they’re designed to be touching food, that gives you an extra level of safety because those are food-grade material while other materials may not be. So if I could get it, I would go medical grade; if I can’t, food-grade is the next best. From there, I use conference bags because they’re designed to be the same structure as far as fiber density and tensile strength and weight in GSM, they’re very similar. If you’re using interfacing, you just have to make sure it’s not diffusing interfacing and that it’s free of adhesives. A lot of those adhesives are latex-based. Latex allergies and sensitivities develop over time, so the more exposure you have to them, the more likely you are to develop allergies. So breathing that in constantly close to your face…
ETG: Could create a latex allergy even if you didn’t have one because latex is not something you’re supposed to be breathing through. Is that what you’re saying?
JS: That’s what I’m saying. In general, we know there are so many bad things about inhaling adhesives. I’ll look into the latex bit a bit more, but that would be really problematic.
ETG: We had gotten into learning about H600. I think on your site somewhere you say don’t use that.
JS: Halyard H600 is not just spunbond NWPP; it also includes melt-blown NWPP. So that changes your risk profile. It’s really commonly used in clinical settings, so people have a lot of access to it. I haven’t seen breathability data on it yet. I have made some masks out of it with a single layer, and it’s a little hot and humid for my liking.
ETG: So it’s the breathability you’re worried about rather than safety. It seems like the company is freaking out a little bit that suddenly their surgical wrap is being used for a mask.
JS: There are a whole bunch of potential reasons for that, and I don’t have all the answers. I do know that for melt-blown in general when you cut it, it leaches smaller particles into the air. The particle size from the melt-blown is a size that’s really bad to inhale.
ETG: So stay away from those because we just don’t know, and they’re hard to get, anyway. We’ve tried.
JS: It’s hard to get, and in order to get improved performance on the water resistance especially, they often use surface treatments and coatings. Some of those are things you really don’t want to be inhaling. I have no data about whether or not the Halyard H600 uses that. That’s the challenge when you’re dealing with alternatively-sourced materials. You’re using things outside of the normal scope. Before I recommend things, I try to do a hazard analysis to try to determine all the safety concerns. So it’s a cautious world of more good than harm. One of the advantages of cotton is we’re very familiar it; we’ve been using it for over a hundred years; we’re not scared of it. So there are some real benefits to that.
For that spunbond NWPP, I recommend washing it first so you get anything from the manufacturing processes rinsed out at the very least. I’ve done a ton of research into the backgrounds and risks for the materials and the safety data sheets when you can find them. Mostly, you want to find stuff that hasn’t been coated and doesn’t have extra treatments; it’s breathable; it’s going to stand up to whatever your washing/cleaning/disinfection procedures are and that has water resistance and some filtration. Most of the data that’s coming out is on the water resistance of something that you can test at home by flicking water at it. There are all sorts of ways. The cough syrup cups that they give you are a teaspoon of water, which is 5ml. Just put it over a jar, pour the water on, and see if it goes through in 60 seconds. You can make that quantitative, which is nice.
For breathability, I have a DIY at home test for that as well. Some people pick it up, put it to their mouth and breathe through it, but for materials I’m not sure about, I hate the idea of putting it up to your mouth and trying to breathe through it. So I use a toilet paper tube; take an elastic band; put the material over the end; then blow a lint ball or a piece of cotton ball with it and see how far it goes. If you can’t move that lint ball, it’s not breathable.
ETG: That’s such an important component of it. So on Amazon, when I look at the sheets of polypropylene, it’s very confusing. I don’t feel totally comfortable with it. Then I went to the reusable grocery bags. How have you been finding your bags?
JS: My mom found these for me, so I’d have to ask her strategy. I know that we’ve gotten a lot of bags donated from all these conferences that have been cancelled and from grocery stores that aren’t allowed to use them right now. The savings bank in our town had several of them that they were willing and able to donate. Being able to get them on Amazon is a new thing for the past few months. As soon as people realized that they could be used for masks, they were impossible to get.
ETG: There’s a lot of nylon ones, and that’s not what you want.
JS: Right. I can look after we get off the call and see if I can find some search parameters that will help with that. We’re working with some companies to try to get more consistent materials out there more easily. It’s a pain to break down bags and cut them up into masks instead of getting it by the yard.
ETG: That would be the most ideal. I was looking at wholesale companies because you can probably go there and get stuff and just not put the logo on it. I went to one and it said 80 GSM nonwoven polypropylene. What GSM are we looking for?
JS: 80 is good for the outer layer. One of the advantages of using something that’s 70 or 80 GSM is that the melting point tends to be a little bit higher. Sometimes lower weights are made differently, so they don’t hold up quite as well. That’s been one of the challenges with some of the crafting materials is that they don’t hold up to the boiling and sterilization techniques. Most of what that tells me is that they probably have polyethylene in them, which shrinks a lot because it melts at boiling temperature instead of 100C higher.
ETG: Tell us about the thickness and GSM. Are there other thicknesses we should be looking at?
JS: I look for 60 to 80 GSM because that gives you pretty consistent properties throughout – mostly 80. If I can get it, I go for food grade and stuff that’s designed to be reusable. There’s been some challenges with olefin, which you can sometimes get by the yard. I haven’t gotten any. But the melting point of it is more like plastic.
AM: What is the set of masks that in your opinion are harmful? We’ve talked about non-breathable masks and the harm in that. You briefly mentioned single-layer masks as potentially harmful. If you could talk a little more about that and then maybe add whatever else to the list.
JS: I definitely have a Do Not Use list:
- Anything that might have fiberglass in it; vacuum cleaner bags because they aren’t breathable. That comes up more than you would think. People think they just need to get the particle filtration to be protected; they don’t try walking up the stairs with it. So anything that you can’t wear for 15 minutes is not going to work.
- Adhesives, latex, materials with coatings. That comes up a lot with metal-infused materials, which may have antiviral properties although frequently they haven’t been tested for that. That’s hard to do with a DIY home test. That’s often achieved with coatings, which are maybe okay to touch your skin; but just because you can have something contacting your skin, that doesn’t mean you should be breathing it in.
- The other consideration is reusability, which means you have to have a way to clean them and you need to know that all the layers are getting cleaned. That part of the conversation I think often gets ignored because it’s not as cool as talking about the particle filtration. But can you clean it effectively?
- So that leads you into bleach, which both the CDC and the WHO say is an okay thing to clean your mask with. All the little caution flags should be going up because you are putting it over your mouth. So if you do use bleach, which I don’t recommend, make sure you rinse it, rinse it, rinse it. One of the challenges with laundering is that if you don’t get even rinsing you can end up with more bleach concentrations than you anticipate. Though you can smell it at levels where it is well below being hazardous, most of us don’t have a good way to tell where on that spectrum things are. I don’t have a DIY test for that yet, so I say no bleach.
For disinfection, boiling works.
Microwaving is not a great idea because the nosepiece usually has metal in it, and you don’t want to put things with metal in the microwave.
AM: How long should you boil it for?
JS: I recommend ten minutes. WHO recommends one minute. That is assuming that the mask is submerged in the water the whole time you’re bringing it up to temperature; you’re boiling it for a minute; then you’re letting it cool down all the way back to room temperature in that same pot of water. If you do that, then one minute may be okay. There are a lot of variables in that. How hot is it outside? How long does it take to cool down? You’re leaving your mask inside the pot of water for this long period of time and it lends itself to forgetting about the mask in the pot of water. Then you’re leaving it sitting in a warm vat of water for some unknown amount of time, which is problematic.
So I recommend just boiling it for ten minutes and then hanging it to dry. Then you know it’s been at that temperature for a minimum amount of time, especially with masks with pleats or seams; you have multiple layers and you want to make sure that you actually get that heat level consistent throughout the entire thing to maximize disinfection.
AM: Can you give us a laymen version of why one layer is harmful?
JS: I wouldn’t say that it is harmful; I would say that it is less good, which I guess is a hedge. With one layer, you don’t get as much of a barrier, and if there are inconsistencies in the material, if there’s a needle hole through it, or there’s a seam down the middle, with a single layer it increases the odds of things just going through the seams. If there’s a little bit of damage, then that’s a failure point. Two layers reduces the risk of any individual imperfection giving you a straight route out.
AM: So it would act as a diffuser.
AM: That’s why I was asking that question. If you’re only wearing one layer, it could spread the germs out more?
JS: Not as far in front of you but maybe in a broader area in the meantime. It does depend on the kind of material. That would be my concern with a single layer; it goes to both of those.
AM: But a single layer is better than none.
ETG: Can you help us understand that study that came out with the cotton and chiffon? You guys keep chatting while I pull that up.
AM: I come from a school of public health where I was a PhD student. I came into this problem as the person that was putting all the hospital requests together so that people were donating through sanctioned channels. My big concern as someone that is worried about liability is we want to make sure that the masks are going to the administrators who can make sure they’re being used in a clinically-appropriate way. My next set of questions is about how we can start educating healthcare facilities about these masks.
Have you done that? Have you had a good response from healthcare facilities? Do you have any ideas about how we can continue to do that?
JS: Yes, I’ve been working on that and I have some ideas. One of the things I’ve been doing is keeping up with the regulatory side of things: the FDA guidance, emergency use authorizations, the triaging of supplies there, the risk alternate profiles and all of that.
That’s a challenging one. Most people don’t want to spend a lot of time looking into the regulatory side of things, but a lot of the requirements are put there to help ensure safety – especially as we get into these other, bigger issues.
So for mask makers, an important thing is the labeling; making sure that what is in the masks is known by whoever is using them, especially in healthcare contexts. We’ve talked about latex allergies already. It’s just such a big one that people aren’t used to thinking about. So having the appropriate labeling with what materials are actually in the mask is really important. And then the cleaning and disinfection instructions are required by those FDA labeling requirements. They pretty much apply to people whether they are manufacturers like Old Navy or somebody in their home making masks for their local hospital.
We talked a little bit before about knowing what the mask is designed for and what it’s going to be used for. Clarifying that is going to be important for the general public and also for healthcare facilities. A lot of the masks they need are for patients coming in the door. The requirements for what that mask needs to be are very different than what the requirements need to be if you are going to be in an operating room. And right now, the guidance and things that hospitals are looking for in masks is based on surgical masks, which can withstand synthetic blood at high pressures, and respirators, which are for airborne contaminants. Figuring out how these new classes of masks fit into that is a challenge and has been one of the things that hospitals, administrators and mask makers are all trying to address.
AM: The hospitals are asking for multilayer cotton masks almost exclusively. I think there is an opportunity to educate them about the work that you’re doing and the up and coming science and see if they have preferences for these masks taking into account the differences. I would love to move forward and think about how we can do that in case we have another round.
JS: I think you’re right there. A lot of how the adoption has been going is hospital by hospital. I know in our area we have a number of hospitals that wanted to use the MakerMask designs with the NWPP. We’ve gotten a sense of how we want to wash and disinfect them and for what the requirements and rules are. In general in hospital settings, reusable masks have not been the standard because if you’re reusing a mask you need to be able to disinfect it or sterilize it. And in hospital settings, those words mean very specific things. You actually need both cleaning and disinfection and you need to demonstrate that you are getting the level of disinfection you need. In most of the hospital context, most of the masks being made – cotton or otherwise – is a scary thing because it’s not going through the normal processes. So making masks that can be disinfected and sterilized or autoclaved is important. But it’s not the way they’re used to processing things.
So with cotton, a lot of that is going into the laundering facilities that are off site in many cases. And those processes rely on bleach for disinfection. So that gets me back into whether we’ve actually performed a hazard analysis for the way they’re doing that kind of batch processing of things because most of the things you put through the laundry aren’t things that you’re going to be breathing in.
ETG: We got a recent request from our local library wanting to give out masks to people who come into the library. These kinds of requests come in all the time, and I don’t know – when you think about kids and adults and all kinds of people that are going to come in, I don’t know what the answer is.
JS: I think these are user cases where people with public health expertise really come in handy because one of the things that we really need is a massive public outreach and education campaign on how do you use a mask; how do you wear it correctly; how do you put it on; how do you take it off. Why is it that it’s not okay to pull it down below your nose? Every night on the news I see all these people with masks, and I’m going oh, no. It’s because it’s a new thing for people, so they don’t know that they need to adjust the nose bridge down and that every time they touch the front of their mask and move it around, anything that’s on their mask is now on their hands, and anything that’s on their hands is now on their face, and that’s not good. That goes back into your question about what should the library be using. What people in the library should be using is what people in the grocery store should be using, which is what the general public when they go into enclosed places should be using. That is the thing that the argument rages on. What the CDC recommends is not the same thing as what the WHO recommends is not the same as what I recommend. There’s still so much variation out there that it’s a struggle for everybody.
ETG: This is the American Chemical Society nano-study that was looking at the different layers of fabric. This is the one that’s getting all the attention that was published April 24.
JS: The WHO guidance references a new ACS nano-paper. That’s the one that’s all about the NWPP which was published June 2. It’s been accepted and is available but not in the finished format.
ETG: This one is looking at filtration where you’re looking at breathability and protection. Filtration comes into yours because the polypropylene is what is keeping things out, but they weren’t looking at breathability necessarily; they were looking at…
JS: Pressure differential is their measure of breathability.
ETG: So when you look at this, what do you see?
JS: N95 do well at 99% filter efficiency, and the pressure drop is really small, which is good. As you go up, the pressure drop is a little bit higher though relatively close. If you use a cotton quilt, they’re saying it works okay for…
ETG: This is the weirdest part: They’re saying a cotton quilt is cotton batting and cotton. I’m not sure how that pressure differential is 2.5 when you’re literally breathing a quilt in. That’s bizarre to me.
JS: It is a bit bizarre. One of the combinations that I tested early on I didn’t use a cotton quilt; I used polyester batting with a layer of NWPP on either side. It worked okay in terms of filtration. I know when I was in the desert and the forest and the smoke from the fires was nearly choking me, one of the things I tried was taking my filtered jacket up over my mouth to try to block the air that way. It filters reasonably well, and I’m surprised that their pressure difference was as good as it is.
ETG: They said the way the cotton is put together it’s got a poly urethane scrim, and that’s why it was okay. But they weren’t using polyester batting; they were using cotton batting that had a scrim.
JS: In general, it works. The challenge there is that it is so hot. This is one of those things that gets into the CO2 accumulation and diffusion, which is another can of worms. If you have a loose-fitting mask, it doesn’t matter as much; if you have an N95 cell mask with a really good fit, that batting cracks the air into this weird buffer and you get carbon dioxide diffusing and accumulation, which you don’t get if you’re just using cotton. So quilting I would still say is bad for a lot of reasons.
ETG: The other one that seemed really promising was the cotton/chiffon, and that’s gotten a lot of attention. They gave us a list of what chiffon they used, which we can replicate.
JS: I haven’t done a deeper dive into chiffons. I would have to look at that more closely.
ETG: They did give us the number, so you can look it up at Jo-Ann’s store.
JS: That’s really convenient.
Don’t use anything with spandex. The stretchy materials are bad. I guess that would be my challenge with chiffon. As you pull it tight to get a good fit, it increases the pore size – the gaps and the holes – and your filtration isn’t as good. I’d have to look again at the details.
I’ve been so sucked into the paper that just came out with the WHO guidance talking about the three layers. It’s on the MakerMask website under the Research Blog. I did a quick summary of the findings.
ETG: You must have been thrilled about this study that it really confirms what you were saying about the polypropylene.
JS: I was excited to see somebody say polypropylene in their out-loud voice, yes.
ETG: “Multilayer polypropylene material is superior or at least comparable to materials used in some medical facemasks.” Amazing. Well, I’ve already ordered some bags off Amazon, so we’ll see how that goes.
JS: Being able to have the number for Jo-Ann’s Fabric for the material you can actually get which is the exact thing is just so helpful.
ETG: They did not do that with the cotton, though. They did the same thing with flannel. They got flannel from Wal-Mart, and I can’t find it. They didn’t say what the number was, just that it was from a Wal-Mart superstore. That to me just seemed a little unscientific.
JS: That is a really interesting thing watching all the studies come out about the materials is they’re not as scientific. There’s a gap between a lot of the testing that’s being done and the real-world scenarios.
ETG: I just wanted them to be a little bit more precise.
JS: That seems reasonable to me.
ETG: What their lack of specificity does is makes me doubt their conclusions. That’s the problem I have with it. Because the little bit that I know, they didn’t get right, it makes me not trust the science.
JS: I think that’s a real challenge. They provide information on the porosity, which is good, and the thread diameter. That doesn’t translate to things we can check or verify at home and when we’re trying to source materials. I also call it the apples and oranges problem because everybody measures it slightly different ways and providing different numbers. At least for this, they provided new information on N95’s which they gathered as well. So there’s some formalization. It doesn’t translate the information into something that’s usable by you to figure out how to replicate it. How do you replicate it? How does disinfection and cleaning work? Did they get the same numbers? Can they be cleaned? That’s another big can of worms because the science is so new for that. Before, you were talking about where things were in November. Where was all the data and research for homemade masks in November? The answer was there were very few studies. The materials were even less well specified than we’re seeing in these new studies. In November, most of the science for DIY masks was 100 years old.
ETG: Who’s going to make a mask out of a tea towel? As a quilter, we’re not going out to get tea towel fabric. So there was an interesting disconnect really early on.
JS: And that disconnect makes a lot more sense when you think about it in terms of a lot of those masks were being used for air pollution and smoke, which is not the same as infection control. Nylon may give you a great fit, but how do you take those nylons off in terms of infection control? It’s stretchy, so you’re getting anything that’s on that mask all over you, and then you’re pulling it up over your face, past your eyes, over your hair, so anything that was on the outside of that mask is now on the inside as you pull it up and off over your head; or you have to put your hands in it to pull it up and off. How do you do that without getting anything that’s on that mask all over your hands and your face. I’m just going to say that for COVID, I have problems with using the nylon on the outside. For airborne stuff that you need an N95 for, I think it’s great. If I have some reusable masks for air pollution and smoke, the nylon solution seems fine. But I do not recommend that for COVID.
ETG: I think the science will get more clear. But there’s kind of this weird moment of people almost like: Oh, we’re done with this. There’s a sense of: We’ve moved on.
Masks for Kids/School
What do you think? Do you think we should still be making masks and getting ready for the fall? What are your thoughts as people come back to school? There’s a lot going on at the moment, and I’m curious where masks fit in.
JS: I think that right now is a good time for us to be recollecting and having these conversations and thinking about next steps while we kind of stop and take a breath. Try to spread knowledge about how to wear masks correctly. Try to get that to be pervasive. As we hit summer, I think we’re actually going to see another bump in demand because the masks that we’ve been using in the colder months are not as usable now when it’s really hot. Think about how we’re going to adapt to have masks that provide the best protection we can that we can actually wear while we’re out doing the things we do in the hotter months.
Our target should be to make sure that whatever mask people have on, they’re willing and able to wear it for the amount of time that they are out and about in high-risk areas.
Think about how we make asks for kids and what safe combinations for kids are.
ETG: What do you think that is?
JS: That is a good question. Everything is a little bit riskier with kids because they’re smaller. It’s scarier to be in the unknown there. We’ve been making masks for the kids, and we do scaled down versions of the MakerMasks Surge – the pleated masks. We’ve been doing them with two layers of NWPP. In general, I’m erring on the side of decreasing by one layer.
ETG: Because why?
JS: Because their lung capacities aren’t as big. They’re not exchanging as much air as forcefully as adults. There’s some data that you can break down the age ranges for, but that’s the reason. Kids are not just miniature adults. I used to teach CPR for kids and adults, and the breath size that you use if you’re doing respirations is different. Lung volumes are different, and the force at which everything happens is different. So I want to make sure that kids are something that’s really breathable.
What are the reasons that people take masks off or pull them down so they’re just covering their mouth and not their mouth and their nose?
There are usually two reasons:
- It’s not very breathable;
- It’s getting too hot and it feels kind of claustrophobic.
Both of those things happen when the mask isn’t breathable enough.
So I definitely think you’re way better off doing two layers and wearing it for the entire hour you’re out – and this is true whether you’re an adult or a kid – than having the best filter in the world that you’re only willing to wear for 15 minutes.
ETG: So putting cotton or something that’s comfortable on the inside is completely fine, but having the outside be polypropylene.
JS: That’s what I would do. Just as a reminder, the CDC says no masks for kids under two. Some other countries say no masks for kids under three. I would keep that in mind for young children or anybody who can’t take the mask off unassisted; they shouldn’t be wearing a mask.
For kids that have sensory issues, I do recommend that inner-most layer have a pair of pajamas or anything they love that’s comfortable that they’re willing to have touch their skin. Depending on age, I would make sure they have two masks. We make matching masks for their dolls.
ETG: Can we throw them in the wash? Are they not getting clean enough that way? You did say that you were washing them in a lingerie bag.
JS: I put them in the lingerie bag so the nosepiece doesn’t get deformed. Be careful with the detergents you use, and use the hottest temperature that’s reasonable. The NWPP I hang dry.
ETG: Do you think that would be okay even if you had a cotton side of it?
JS: Yes. It takes longer to dry with the cotton.
ETG: But you’re okay with washing it in hot water and letting it hang dry.
JS: Yes. And if you don’t want to hang dry, tumble dry low.
ETG: I feel like I have some direction. I ordered the bags, and we also have some polypropylene that we got that’s very thin. I’m not sure what that is, but maybe I can putt that between. I’m going to make three layers, two layers, and two layers with cotton so that we’ll have those to test and see how people feel about them.
JS: When I go out hiking, I use a two-layer NWPP.
ETG: Because it’s too thick when you’re really exerting, and you’re not in the middle of people.
JS: Right. For me it’s a low-risk environment. I stay at least six feet away from everyone as much as possible, and it’s an outdoor space so the risk parameters are different. In the grocery store, I want a three-layer one. I’m also used to using masks, and that makes a difference because it isn’t the same. No matter how good a mask is, it’s still different. I have to remind myself when I first put it on to breath easy for a few breaths to get used to it again and not to run up the stairs right away.
ETG: I did housework in a mask just to get used to it and determine at what point does it seem impossible. Just get used to how it is.
JS: That’s the thing I haven’t heard other people talk about, either, is practice. Whenever you’re using a new tool, it takes practice. Facemasks are medical equipment.
ETG: I know everyone is going to be beyond excited to hear this because really, you are who we’ve been looking for. I feel like I have direction, which I really didn’t before.
AM: I’m a health economist and not a science person. I read all the studies and was trying to do the best approximation of what was in the study, but it was a very poor substitute. I didn’t feel like I could replicate it with any confidence. So I think this was really great to have a scientist that actually understands the materials we can get, because that’s a big deal.
JS: And this is a hard problem. If there was one set of best practices everyone could follow, we’d be doing it and it wouldn’t be as hard. It’s hard for everybody to be sorting through all this. We expect the higher-up people to be saying yes, this is what everybody should be doing. We thought we were going to get that in March, then in April, then in June. The world is still converging on best practices, and I think we’re all getting better as we go. That part is exciting.
ETG: It’s been a really interesting intersection of science and sewing that was unexpected.
JS: And DIY efforts.
ETG: You’ve spent some nice, quality time with your mom, I’d imagine.
JS: And she’s way better at sewing than I am, and we have one machine. She’s always telling me I run the sewing machine with a lead foot. Slow it down, and it’ll come out straighter.
Whitney Chatmon, Host:
When all these studies about masks are coming out, and scientific articles in general, how do you go about analyzing the research and what do you assess when you’re looking through all of it?
JS: That is a really good question and probably a whole course.
WC: I found myself recently reading some research, and I was – I haven’t taken science since I was a freshman in college.
JS: I first check to see if they’re original research and if they’ve been peer reviewed because that makes a big difference. A lot of the stuff that’s coming out is meta-analysis, which is stretching back for three decades. I read all those older papers at the beginning, and I’m curious to see what the new ones are. I would look to see if they have error bars; if they have more than one sample. A lot of them are using the same word: particle filtration. Particle filtration means about a thousand different things depending on who’s saying it. I look to see if the method they’re using is the same as anything else and anywhere else because if I can’t compare it to other things, it’s not super helpful.
WC: I was wondering given your personal history with respiratory illness, how did you view the current pandemic when it was starting and the progression of it?
JS: I think it meant that I was cautious earlier. I actually went to Las Vegas for a conference in January, and I knew I was going to be backpacking for a week in the desert afterwards without having any contact with what was going on. So I went to that prepared. I had my masks with me. I wear a mask when I fly all the time, anyway, because otherwise, seven days after getting off the plane, I would get a new respiratory illness.
Then because of my previous respiratory history, I have almost every able commercial reusable mask that was in existence before, as well as disposable masks. So I had a full set of them to be able to compare and a lot of experience with what I liked and disliked and absolutely abhorred in masks. So that gave me some context to be thinking about it about a month earlier than a lot of other people were.
ETG: COVID-19 causes blood clots in your respiratory system and a lot of other things. How did you feel about that, personally?
JS: I think like everybody else, nervous. It’s scary. I’m a first responder, too, so my first impulse was to want to get out on the front lines and help. It was really hard to not be in a position to help in the way that I wanted to help. For me, deciding to pour my heart and soul and science into these mask efforts was my way of helping because I couldn’t physically be on the front line. So I wanted to do what I could for my friends who were: the first responders, EMTs, firefighters, the people who show up on the scene and weren’t being prioritized in the triage of who needs PPE. So as a former EMT, as a first responder, I want a mask that’s going to provide me as much of a barrier to bodily fluids as I can get.
WC: Through all the interviews and things that we’ve been doing, I think the main thing I’ve found is that the people who have been getting involved with the effort of mask making, it’s become a way of coping with everything going on with the pandemic.
JS: Yeah, it’s a way to channel the energy into something positive.
WC: I had so much anxiety about everything going on. Just cutting fabric – even though it was mindless labor almost – was so calming in a way because I felt that I was helping and I was taking control.
Making Masks is Trail Magic
JS: Finding the things that you can do. As the pandemic initially was spreading, and it felt like something we couldn’t do anything about, I think for me at a secondary level – the first level was I have all this information and all this stuff about masks and my family, and all the backpacking I’ve done walking across the country three times for the Appalachian Trail, Pacific Crest Trail and Continental Divide Trail, I have pockets of family that are scattered up and down the country all over the place in rural America. They’re people who have opened their hearts and their homes and invited me in and have made me part of their family that were complete strangers. We call that trail magic.
WC: I believe it. I’m from Appalachia.
JS: So I feel like all the people who are coming together to make masks are providing a version of that trail magic on a much bigger scale. We have these resources and supplies and skills that we can put out there to try to make things just a little better even if we’re one person or one day; it’s something we can do. That part is really what renews your faith in humanity when a lot of other things in the world may not.
ETG: That’s part of why we’re doing the Summit to bring everybody together, have these conversations, but also record and celebrate. As part of it, we’re doing a giveaway: If people sign up, they get entered into a giveaway that all these companies have donated as a thank-you to the sewists who have been working so hard.
JS: A lot of people are in positions already where the need for masks isn’t as great, but that isn’t everywhere. The stuff I see on the news makes it seem like everyone that needs masks has masks, and that does not match the reality that I’m living in. The shortages are expected to continue. That gets into some of the more complicated issues of whose voices are heard and which stories are being told.
ETG: The story of the masks is really multifaceted, and I think it brings up social inequities, economic inequities, and now we’ve got politics injected into it in a really stupid way, and then all of the supply chain; so there’s just a lot to all of it.
JS: One of the questions I was not expecting was: What do you do when you get tear gas or pepper spray in your mask?
That is a really legitimate question and concern right now.
ETG: So now you need at least two masks when you go out because you’ve got to have a backup. But what do you say to that?
JS: What I say to that is there’s a lot we don’t know. I haven’t seen any studies with pepper spray and masks. But what it really means is that you should change the mask as soon as possible, especially because if you have absorbent materials, it’s going to be the gift that keeps on giving.
ETG: Polypropylene might help because it will act as a barrier more than cotton would.
JS: If it’s in a water-based or droplet-based form, it may help. Once again, this gets back into the privilege of how many masks you have. And if you don’t have a sewing machine and you haven’t been sewing your own, you may not have a dozen masks even though that’s a target that everybody should be working towards because as soon as it gets wet or dirty, you should change it.
ETG: The concern that I have is that we’re looking at these commercial masks and they’re just all over the place. A lot of them are super cheaply made and you don’t know what they made them out of. They seem kind of dangerous to me on some level. You just don’t know. There’s no rating system; there’s no requirements; there’s no standardization.
JS: All you have to do is have a label. If it doesn’t have a label telling you what the materials are and how to wash it, it is not okay. You have to be able to know what’s in it and know how to wash or disinfect it.
ETG: We’ve ordered some commercial masks, so they should be showing up at some point. We haven’t talking about shields. Tell me what your thoughts are about mask+shield. Do you think that’s a good thing?
JS: Yes. Face shields are just another piece of the puzzle. I think face shields are a good thing. The data out there says they’re not the same as masks, so a face shield and a mask is good. I am not a face shield specialist. There are other people who have done all the research and analysis there. Certainly, if you can do a mask and a face shield – eye protection is good.
ETG: Are glasses enough or do you want goggles? I’m going to be so suited up when I finally leave my house!
JS: And it’s going to be 95 degrees.
ETG: And I’m going to fall over.
JS: Here we go into another topic about heat stroke and heat exhaustion and making sure that you are hydrating appropriately. If you’re wearing a mask and/or you’re out for a long period of time, you need to drink. How do you drink without touching your mask?
ETG: We’ve seen joke ones with the straws. It’s not good. That must make you completely insane.
JS: If we’re talking about things that make me cringe, we can talk about the masks with the exhalation valves because they’re blowing all of your respiration all over everybody. We talked before about if you have just a single layer it might act as a diffuser and spread everything out, but a ventilation valve might act as a focuser.
We were talking about the straws. Anything that goes in and out through that control area of the mouth is bad.
ETG: And you know they’re going to be popular in New Orleans.
JS: Like all these things, there are better ways to do it and worse ways. How do you get the straw in without holding the bottom of the mask? Now you’re touching the mask in two places. At least minimize the points of contact. I do have some with straws.
ETG: They’re going to be on Bourbon Street, and they’re wearing a mask with a straw hole. Maybe that’s better. I don’t know.
JS: That’s that thing with why is it people are saying maybe we shouldn’t open bars. Alcohol does inhibit boundaries. People aren’t as good at paying attention, not as good at motor control. Wearing your mask while drunk.
WC: During the beginning of things really exploding, I knew people who were going to the bars, and I was like: Are you crazy? And they were like: The alcohol will kill the virus if it’s in my mouth. I’m like: Okay. That’s a strange and very risky line of thinking.
JS: It’s a common one. I shouldn’t legitimize any of it, but the proof you need your alcohol to be at for it to act as any kind of disinfectant is 160 proof.
ETG: That’s just a challenge to some.
JS: If the alcohol you’re drinking is 160 proof, then you have a lot of issues ahead of you. The chances that the behavior being engaged in while drinking alcohol of that proof is risky is high. That is true with or without COVID as an additional risk factor.
So, we’ll just say no on the alcohol acting as a disinfectant. We can dive into the data of how risk is likely to be amplified in those circumstances, but certainly it is in a lot of different ways.
So drink responsibly; wear your mask responsibly; do all the things as responsibly as you can, realizing that nothing is perfect but you’ve got to try. If we all do a little bit better as we move forward, that’s going to amplify and hopefully we get better and better and better until we get nearly there.
I’m hoping that as we go through the summer and the pace is maybe not quite as frenetic as it was at the beginning, it gives us a little bit more time to think about the whys behind the things we’re doing instead of just doing it in panic mode so that we can move forward more responsibly.
ETG: I think that’s very true. It takes time to do the science, so it’s interesting to watch what’s happening with that. To watch science work its thing, that doesn’t happen very often. My kid’s best friend’s mom asked me if I saw the ACS study on masks. This is regular conversation now, which is so fascinating and awesome in some way, right?
JS: Right. And there’s this new study that the WHO references that hasn’t made it quite into the full cycles yet.
ETG: I can’t wait to see it.
JS: The link is on that MakerMask webpage.
ETG: Well, you’re amazing, and you’ve given us so much time. We kind of super geeked out on you, and I know everybody is going to be so excited to listen to this.
JS: This is a dialog that we’re all going to keep participating in. That’s the important bit.