Today, the mayor of my city, Minneapolis, announced that next week cloth masks will be mandatory here in "indoor spaces of public accommodation." So that seems as good a time as any to write a fairly practical post.
In other words: Today I tell you how I do something that, if you wanted to do it my way, you'd probably be able to figure it out yourself. But hey, why not, I'm a little writer's-blocked.
Disclaimer: I am not a professional dispenser of legal or medical advice, and I have not done an exhaustive literature search regarding polyester knit fabric and droplet control, only a cursory one. I hope to get around to that sometime before I start shopping in stores regularly again. But I'm also not going to let that stop me from blogging.
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I'm going to show you the fog-free, not-too-sweaty, NO-SEW mask method I came up with using things I already had in my house.
What I already had in my house: about six of these stretchy polyester tube bandannas, or you might see them called "multipurpose running headband."
Most of the ones we have are made by Buff (available at a lot of different places, including REI and Amazon). Buff Original Multifunctional Headwear is a little heavier; Buff Coolnet fabric is a little more lightweight. The one I am showing you today is an adult size, but personally, I prefer the junior/kids' size; it fits a little tighter.
All those will run you $20-26 at full price. You can find similar, much less expensive ones at Decathlon (like this one); my favorite is the Quechua MH 500 Children's Hiking Headband, though just now it seems to be out of stock in the US. Here it is in the UK.
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A word about stretchy polyester as a mask material:
I wish I didn't have to waste time explaining this, but I'm talking about community masking for source control here. I am not talking about self-protection, and I am certainly not talking about the kind of PPE you need in medical settings or being a caregiver for sick people.
A homemade cloth mask for community masking has two purposes. (1) to reduce the number and velocity of droplets that come out of the wearer's mouth and nose into the surrounding environment and (2) to comply with building rules or local regulations that require people to wear cloth masks when they are around other people.
Perhaps such a mask will also confer some protection against inhaling other people's face-hole droplets. That is beside the point for my purposes. I'm wearing this mask to help protect my neighbor, just in case I am an asymptomatic carrier of infection. I am glad to see my neighbor wearing a mask to protect me.
Those formalities out of the way: I am not representing this type of mask as more effective, as a community protective strategy, than any other type of cloth or paper mask.
There is reason to believe that some fabrics are intrinsically better than others at filtering out droplets of the relevant size. Konda et al. put out a preprint describing air filtration experiments in which they passed air containing aerosolized saline through fabric samples; different fabrics showed very different results, and combinations of fabrics appeared to be generally better than single fabrics. They caution, of course, that the intrinsic filtration efficiency of the fabric isn't the only important factor. Indeed, the better the mechanical filtration, the more air pressure it takes to breathe through the mask fabric, and the more likely that air will escape around the edges. The shape of the mask and how it fits to your face are factors---as well as whether you find the mask comfortable enough to keep it on.
I have been watching for data about hydrophilic and hydrophobic mask fibers. A lot of people are writing about cotton quilting fabric and not that many people are writing about polyester knit. Polyester is generally a hydrophobic, water-repelling fabric, although the manufacturer may have treated the surfaces of the fibers in ways that affect their hydrophobicity; and often you find it in blends with hydrophilic (water-attracting) fibers such as cotton. One might expect that a hydrophobic fiber network would be less likely to catch droplets of water-rich spittle than a hydrophilic one. But Konda et al. found that a polyester-Spandex chiffon fabric (a woven fabric, not a knit) was a remarkably efficacious filter medium, possibly because it---like the material in N95 masks---holds an electrostatic charge that traps small particles. A relatively new preprint by Aydin et al. is notable because not only does it include data on polyester knits, it considers the breathability of the fabric and also how easily it becomes soaked with moisture.
I'm not aware yet of much data regarding the effectiveness of different kinds of fabric in actual use, sewn as masks, and fitted onto people's faces, at filtering air that actually contains viral particles. But it does seem clear that wide acceptance of plain paper unfitted surgical masks significantly reduce the spread of respiratory diseases. So for now, I'm going on the assumption that, with community masking, the most important thing is that as many people as possible find a well-fitting mask that they can and will wear, comfortably, whenever they are out.
And I think this is pretty comfortable, and fits nice and snug with no air going around the edges. I can add an extra layer of filtering fabric if I want. So this is the main thing I do when I am out and about.
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Step by step, starting with the multifunctional running headwear:
1. Put it around my neck, before clipping my hair out of the way. Then wash hands!
You might like the way it looks more if you put it on reverse-side-out at this point, but for me it works best right-side out.
2. Spectacles out of the way, the top edge goes over the nose.
If you are very, very sensitive to having tight fabric covering your mouth and nose, you could stop here. This fits very loosely and covers well past the chin. It will comply with most places' rules about wearing face coverings, I expect. I would recommend taking up some of the slack, if there is any, or else using clips to secure the back of your mask into your hair or perhaps to your hat. It's better if you don't have to adjust it and if it doesn't fall down by itself.
But I want a tightly-fitting, secure mask with more layers over my face, so...
3. Take hold of the bottom edge of the mask where it passes behind your neck....
4. .... and pull it up, flipping it reverse-side out. You can pull it as far as up over the top of your head.
How far you pull it depends on how tight you want that edge to be under your chin.
Right here is where I stop when I am using the bandanna to make a face mask for my six-year-old and my ten-year-old. It is comfortable, it stays put, and they think they look fierce in it.
5. Now we tighten it over the nose. We do this by grabbing the other edge of the mask, the one that crosses over your nose and under the part covering your ears, and is now behind your neck. Grab it and pull it straight away from your neck. You will feel that edge tightening over the bridge of your nose.
6. Then, much like you tightened the first edge, pull it up behind your head, folding it right-side out. Again, how far you pull it depends on how tight you need it to be over your nose. Don't worry if it isn't perfect quite yet.
7. You may have noticed that, so far, there's only one layer of fabric over your nose and mouth. Let's fix that. There's plenty of extra fabric to fold here. You can fold the top edge down, showing the reverse side of the fabric, and get two layers quite easily. (If you stop here, maybe you would prefer to have started with the bandanna reverse-side-out.) But I prefer to do a little fancier folding...
8. Flip that edge back up and now there's three layers over the nose.
9. You can do a similar thing with the bottom edge and get two or three layers over your mouth. I do find that, however you fold it, it's better to have the very bottom edge go under your chin instead of across your face in some way, since that helps it be held snugly over your face by the tension of the edge passing over the top of your head.
This makes a little pocket which you can use to add an optional extra layer of filtering material!
Today's optional extra filtering material will be Scott Shop Towels, cut into a shape that seems to stay put on my face in this mask. I am not recommending this particular fabric for any other reason besides the fact that I have it in my house and it is an absorbent non-woven breathable food-safe fabric that I can cut with scissors, which happens to be a color that contrasts with my mask so you can see it in the pictures. I don't actually know what they are made of (apparently Scott keeps that secret). Replace it with anything that you have decided will enhance your face mask.
10. If I am using the extra filtering material, I tuck it behind the folded-over flaps, both the one coming down over my nose and the one coming up from my chin. This takes some adjusting of the folds to make sure I have enough material to work with.
11. A little fine adjustment across the nose. I take up a little bit of slack and pull it below my cheekbones at the edges, by tucking it further under the twist at the temple.
12. Eyeglasses (fog check: zero) and hat. Done!
Here are the advantages I see to this type of face covering:
- Machine washable, quick-drying
- Sweat-wicking fabric
- Easy to obtain two, three, maybe even more layers across the face
- Fairly stylish
- Can vary the tightness from quite loose to quite snug
- Can put in an extra filter if you want
- I bet you could wear it over an N95 if you wanted to
- YMMV, but it doesn't fog my glasses
- No sewing
- Stays in place, no need to touch it frequently
- Kids seem to like it
- Doesn't hurt your ears or tangle in your hair (though I'm much more comfortable with my hair put up)
- Without the extra filter: Easy to breathe through
- If you take it off, for example, to drive from place to place, it will just stay comfortably around your neck
Potential disadvantages:
- Polyester knit is fairly loose-weave and its specific filtration efficacy is not known. This is the biggest caveat. It's one reason why I try to get at least three layers over my mouth and nose.
- Some brands are pricey
- Maybe it will fog your glasses and you'll have to add some wire or something
- It's a little hard to get it just right without a mirror (at least at first)
Give it a try and see what you think.
Repeated Disclaimer: I am not a professional dispenser of legal or medical advice, and I have not done an exhaustive literature search to determine if there is any other available data regarding polyester knit fabric as part of masks for source control in the community.
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