Recommended Designs for a Homemade Mask? - Printable Version
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Recommended Designs for a Homemade Mask? - Snorlax94 - 04-06-2020
I've read that, for homemade masks, blue shop tools used with cotton can provide a balance of protection, breath-ability, availability, and re-usability. However, I haven't found a good design that uses blue shop towels. In a BusinessInsider article, a garment shop claims they've developed and tested a proprietary design that they will "share with the world" soon, after raising a $200,000 GoFundMe to "donate" masks to nearby hospitals. Yet somehow there are no signs of the free design, and no details on the research that went into their proprietary design.
The WaPo article provides a link to a YouTube video that demonstrates a very basic design that uses a blue shop towel, staples and rubber bands, but that design appears to favor ease of construction while unnecessarily sacrificing fit, effectivness, durability and reusability.
Is anyone aware of a design incorporating blue shop towels with cotton, or any other high-quality design? I'd like to make some for myself and my family. Although I have a handful of disposable masks due to my sensitivity to wildfire smoke, I'd like to have masks my family could wear more regularly, so to achieve this, it seems like I'd want washable, re-usable masks for everyday use.
From the WaPo:
Peter Tsai, the materials scientist who invented the electrostatic charging technology that N95 masks — the highest-quality medical masks on the market — rely on, also believes that homemade masks are an important part of the United States’ battle against the coronavirus. He offered another material for DIY mask makers to consider: nonwoven fabrics.
Nonwoven fabrics, which Tsai did years of research on to improve medical masks, are made of individual fibers or filaments that are bound together mechanically, thermally or chemically. They are not knit or woven together, like most cotton.
Not all nonwoven fabrics are ideal for masks. Wet wipes are made of nonwoven fabric but are too porous, Tsai said. Vacuum bags are also generally made of nonwoven fabric but are not breathable.
Tsai recommended using car shop towels as mask material. The towels, available in rolls and often blue in color, would do a better job of filtering droplets than cloth, he said. The material is “very strong,” he said. “And it can be washed with soap and water and reused.” There are YouTube videos that offer tutorials on using this material.
The towels, he said, could also be used in conjunction with cloth masks, serving as an additional filtering layer. Still, like MacIntyre, he said that cloth is better than nothing. “Any cloth material can help. It is not perfect, but it can stop large droplets from getting out, and from getting in,” he said.
Frustratingly, the WaPo article adds:
Kaiser also has a pattern for a nonwoven mask, but it is not sharing that design publicly with volunteer sewers. “We want to allow people to access what they have at home,” said Jodie Lesh, a senior vice president at Kaiser Permanente who is leading the homemade mask initiative.
https://www.washingtonpost.com/lifestyle/wellness/masks-diy-coronavirus/2020/04/01/20830f5e-7420-11ea-85cb-8670579b863d_story.html
Businsess Insider article:
https://www.businessinsider.com/homemade-mask-using-hydro-knit-shop-towel-filters-better-2020-4
RE: Recommended Designs for a Homemade Mask? - M T - 04-06-2020
(Remove the "XXXXXX' in the youtube video links below.)
I am about to make some masks for a small medical facility use, per this video (pattern, directions). I bought 12 HEPA cloth vacuum bags to be delivered Wednesday. I don't yet know what the breathability will be. The duckbill shape offers more flow surface area than a flat mask.
(We are going to use tie straps rather than elastic.)
This article documents the filtration capabilities & flow characteristics of various fabrics. (Tea towels = dish towels. I believe this to be this are not the linen variety.)
This article echoes the filtration capabilities per the above article. Of interest is that doubling a dish towel gives effective filtering to be equivalent to a surgical mask. Doubling other tested fabric didn't help much.
This article measures the filtration effect of DIY masks, as worn. They do seem to be effective.
JoAnn Fabrics has a lot of support for this, and there are tons of other designs & how tos all over the net. Note that you want to avoid using pins during construction.
Lots of people are making these. JoAnn Fabrics indicates their "partners" have made 28M masks of a goal of 100M.
Our local NextDoor indicate a tailor in downtown Los Altos is selling some at $8.
An issue is sanitizing. After looking at the possible sterilazation mechanisms (beyond discard & use new) for home use, I think I would choose to heat the mask to 170 degrees for 30 minutes. Consider that when choosing your materials. That is one of the reasons we aren't using elastic. (I do not know how the HEPA cloth will respond to that. Follow the iink for lower temps & longer times that work.
I also considered the ease of putting on & off the mask without touching the front of the mask. The original elastic design on the vacuum bag mask above looks to me to be difficult to put on without touching the front of the mask.
Another mask design that I thought was interesting, but has a bad flaw IMO, is this one The problem is that when you untie the straps, the outer, dirty part of the mask falls onto your chest, now making your shirt dirty.
RE: Recommended Designs for a Homemade Mask? - burger - 04-06-2020
(04-06-2020, 12:34 PM)M T Wrote: I am about to make some masks for a small medical facility use, per this video (pattern, directions). I bought 12 HEPA cloth vacuum bags to be delivered Wednesday. I don't yet know what the breathability will be.
Probably awful from my experience and what I've read. We got some non-HEPA vacuum bags, and we're using them as the middle layer between two layers of relatively tightly woven cotton. Breathing through all of this is a chore to the point that I have to focus on each breath. I'm a runner, and there were still moments while walking around the grocery store where I felt like I wasn't quite getting enough oxygen. I understand now why people have passed out wearing masks in public.
I saw a test of several mask materials somewhere, and HEPA vacuum bags had among the lowest breathability ratings. I would not recommend these for anyone who has any breathing difficulty.
RE: Recommended Designs for a Homemade Mask? - BostonCard - 04-06-2020
Bear in mind that wearing the masks is more about source control (protecting other people from you, on the chance you are infected and don't know it) than from protecting you from other people. It might, if the discomfort of the mask results in you touching your face to adjust it often, marginally increase your risk rather than decrasing it. But having a cloth barrier will reduce droplets you expel and cut down on the travel distance of turbulent gas clouds.
See the videos in this article, for example:
https://jamanetwork.com/journals/jama/fullarticle/2763852?resultClick=1
BC