The best (and worst) materials for DIY masks

I used hepa air-conditioner filter for the outside layer and cotton for the inside. The box filters have the fabric accordion-ed into them so there is actually a _ton of material to use. Very breathable and basically n95 quality.

As for the article, remember that the important thing is the trapping of _your exhalation, preventing any viral particulate to be put into the air in the first place. So, basic cotton covering is actually helping out a lot! If it’s comfortable to wear, more people will wear them, and with more people wearing them it will feel less weird and the trend will continue.

Masks are definitely helping, and we still have a long way to go till a vaccine or something permanent.


Well, it won’t hurt to make the assumption that the outside of the mask is contaminated. If you stay more than 6 feet from people, then you probably aren’t exposed to exterior droplets the source control mask could filter.

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Don’t go to a bar for four hours and think you’re risk free because you’re wearing a mask.

If you go to a bar for four hours without removing your mask to take a sip it is a waste of everybody’s time or a soggy mask.


Wilson and her team collected data from various studies of mask efficacy and created a computer model to simulate infection risk, taking various factors into consideration.



It would help the company because, while the 2 masks & filters were free, the replacements are available for purchase.


Are ‘pocketed’ masks designed in a way that allows the additional, inserted filtering material itself to properly seal around the face properly? Otherwise…

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None of the ones I have seen do anything other than position the relatively small sized insert filters centered in front of your face, and do nothing to prevent air from going the easy route around the filter through the rest of the cloth mask, or through the non-existent seal of the mask against the face.


I stuff mine in a clear baggie for 24 hours. It’s not a biohazard. I wash my hands after touching it.

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DIY mask patterns with a pocket typically mean one edge or part of an edge between the inner and outer fabric isn’t sewn shut. The entire mask is effectively the pocket. Any coverage of the filter vs the full size of the mask depends on the size of the filter used, ability to fill the entire space, and ability to stuff it through possibly a small hole.

On the pleated rectangle type, the hole is typically on the bottom edge or in the middle of the inside. It could be almost full width of the mask or just a two inch slit in the middle.

On the curved shaped type, it’s typically on one side. It could be the full height of the side or less.

For both, you’re slipping a filter in and spreading it out to fill as much of the interior as possible.

PS: I’ve clearly watched/read to many mask making instructions, but I’ve almost got exactly the right fit for myself now. I like the exterior tea towel and interior pillow case. :slight_smile:


I suppose the “coverage” of any inert would also be dependent on how well it conforms to the face (softness; flexibility; stretch-ability)

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The stories I’ve read of front line medical personal having to reuse N95s (yes, I know, a different level of mask and exposure) has had them storing the masks in a paper bag, not a plastic bag. I don’t know why that is, but I have read that Sars CoV 2 remains infectious less on paper than on nonporous surfaces, and that you want to keep masks dry to keep bacteria from breeding. So a plastic bag may have some disadvantages.

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mildew and mold. nobody wants to wear a stinky mask.

I put my bag in the window, it gets a little sunlight and heat. The sunlight can damage the cheap surgical mask I use, so eventually I’ll have to throw it out.

Yes it’s a few hours difference.

I already had mice ruin a entire box of surgical masks left in my car. I keep them in a zip lock and that seemed to be enough to keep them out. I really don’t want to inhale mouse droppings in my masks, that’s probably worse than COVID-19. (hantavirus and leptospirosis)

Ultimately it’s pretty pointless to try and optimize your masks. People generally focus on the wrong things with masks. They want replaceable filters, or swear by special decontamination rituals, or “high performance” N95 masks.

People aren’t wearing masks correctly enough or consistently enough for any of that to be the long pole here. Maybe have a professional show your family how to wear their mask if you’re looking for ways to be more effective.

I’m satisfied if most (95%>) of people are at least typing a bandanna over their nose and mouth. Anything else is gravy. Taking your mask on and off to drink your coffee is not great. Not putting the mask over your nose is also not great. When I see people do this, it gets very easy to think: why bother.

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I read the car windshields have UV filters in them, so you get the heat but little or no UV sanitizing, or UV damage.

Most glass limits the amount of UV somewhat. Yet my carpets are faded, so I think my window is pretty much fine. I’m mainly going for a little heat rather than a lot of UV.

I feel more comfortable with easy to measure things like temperature than assumed powers of an unknown UV source.

Pretty sure the sun is a known UV source, with plenty of data.

Certainly more so than those UV lamps offered by fly by night Facebook advertisers, which may just be purple LED lights :slight_smile:

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The cloth masks we’ve been wearing are layers of cotton (stained cotton shirts and tshirts repurposed) with a layer of silk in between. I’m using the closing ties from Aldi coffee bags for nosepieces - they remain flat and against the skin comfortably, and we haven’t had problems with glasses fogging.
I’ve tried 4 different patterns so far, and the ones that work best far everyone’s faces is the “nurse approved” version that has a seam down the front, and casing instead of pleats on the side. The casings are threaded with strips cut from spandexy leggings with holes, straight across the back of the head and tied at the back neck.
But YMMV, as everyone has different favorites and different needs.

eta: if you’re using t-shirts, remember that no matter how cool it looks, you can’t breathe very well thru a screenprint. Yes, I was that dumb in the service of fashion…


Yes, I do. It’s in the Ongoing Coronavirus Happenings topic, I think. I’m going to look for it. Not sure if Lancet, but definitely testing different fabrics, and a combination of cotton and synthetic layer was most effective. Cotton and silk was also good. Supplementary material of the paper provided info on exact materials used including manufacturers.

Your description BTW is accurate, mechanical filtering plus electronic filtering was the explanation for effectiveness.

Ah, originally posted it in the DYI topic, but linked it in the Happenings topic.

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Is heavy coffee filter paper still considered adequate for exhaust filtration?

Because “filtration” is the wrong mental model to use for what the masks are doing. They are spit traps. Spit will not take a hard dogleg left around your filter insert.

The CDC is recommending a coffee filter in the pocket of homemade masks so that’s what I’ve been doing.

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