topic Re: Study determines best fabrics for face masks in Community Chat

Study determines best fabrics for face masks

novamc1 — Sun, 10 May 2020 16:58:05 GMT

Homemade masks made of silk and cotton may boost protection: study

by University of Chicago

"There is a huge interest and need for homemade cloth masks but we found little data on how good various fabrics are as filters for masks," said senior author Supratik Guha, professor with the University of Chicago's Pritzker School of Molecular Engineering and a scientist at Argonne. "According to these results, it's possible to get very good filtering with commonly available fabrics, but the wearer only gets maximum protection if the fit is very close to your face."

COVID-19 is thought to spread mainly through respiratory droplets created when an infected person coughs, sneezes, speaks or breathes. Guha and his colleagues wanted to study the ability of common fabrics, alone or in combination, to filter out aerosols similar in size to respiratory droplets. So Guha—in regular times, a leading scientist in microelectronics and materials for quantum information—quickly rigged up an experimental setup with his colleagues to test combinations of fabrics that can be bought at fabric and retail stores.

The experiments took place in two plexiglass boxes connected by a tube. In one chamber, the team created a cloud of particles and blew them toward the tube, which was covered by different combinations of cloth. Mike Schmoldt and Greg Moss, environmental safety experts at Argonne who specialize in respirator testing and the effects of aerosol particles, used laboratory-grade scientific instruments to measured the number and size of particles in the chambers before and after passing through the fabric.

According to their results, one layer of a tightly woven cotton sheet, combined with two layers of polyester-based chiffon—a sheer fabric often used in evening gowns—filtered out the most aerosol particles (80% to 99%, depending on particle size). Substituting the chiffon with natural silk or a polyester-cotton flannel, or simply using a cotton quilt with cotton-polyester batting, produced similar results.

Though the study does not attempt to replicate real-world conditions, the findings are a useful guide. The researchers pointed out that tightly woven fabrics, such as cotton, can act as a mechanical barrier to particles; whereas fabrics that hold a static charge, like certain types of chiffon and natural silk, can serve as an electrostatic barrier. The electrostatic effect serves to suck in and hold the tiniest particles, which might otherwise slip through holes in the cotton. This is key to how N95 masks are constructed.

However, Guha added, even a small gap reduced the filtering efficiency of all masks by half or more, emphasizing the importance of a properly fitted mask.

Fabrics that did not do well included standard polyester and spandex with more open weave. In general, Guha said, fabric with tighter weaves—with fewer gaps between the strands of yarn—worked better.

"This is some of the first methodical data I've seen on homemade masks. It's very helpful to have some idea of how the different types of fabric perform," said Emily Landon, executive medical director of infection prevention and control at the University of Chicago Medicine. "I was also pleasantly surprised by how effective some of the homemade masks can be in the right conditions."

Landon noted that the advice to wear homemade masks while out in public is intended primarily to protect others from your own respiratory droplets, and that universal adoption of this recommendation will go a long way to make everyone safer.

In that case, any mask is better than none.

The first author on the study was Abhiteja Konda with Argonne National Laboratory. The other authors were Argonne's Abhinav Prakash as well as Pritzker School of Molecular Engineering graduate student Gregory Grant. The team used the U.S. Department of Energy's Center for Nanoscale Materials user facility at Argonne National Laboratory.

Re: Study determines best fabrics for face masks

QueenDanceALot — Sun, 10 May 2020 17:12:17 GMT

I watched a video of one of those infrared tests on a news show to show the difference between wearing a mask and not.

I will continue to wear my mask while out and around others. And all of mine are made of cotton.

Re: Study determines best fabrics for face masks

Twins Mom — Sun, 10 May 2020 17:13:21 GMT

Thank you for posting info. I have been trying to purchase material on line but difficult to analyze tightness of weave. And needless to say, fabric availability also limited.

Re: Study determines best fabrics for face masks

granddi — Sun, 10 May 2020 17:25:58 GMT

The very best masks are N95 and cost pennies.

Where are they?

Regular citizens should not have to be scrambling to figure out how to protect ourselves.

We all want to open up activities as usual but without adequate personal masks for those who chose to use them, it is not without risks.

Many new outlets are reporting a company in Fort Worth Tx offered to start up production of N95 masks. After over 2 months of back and forth (between Jan and March), they finally have plans to start manufacturing masks. Of course health care workers should get the masks first. But ordinary citizens should be able to access these masks also.

Re: Study determines best fabrics for face masks

CelticCrafter — Sun, 10 May 2020 17:38:06 GMT

@Twins Mom They say if you are going to make your own use a quilting cotton. Most fabric websites do have the quilting fabrics broken out into their own category.

Re: Study determines best fabrics for face masks

Cakers3 — Sun, 10 May 2020 17:40:20 GMT

I also make masks for DH and me. I use the tri-fold method with heavy yarn. I like this method because you have ear loops, a way to tie across the back of your head and a way to tie across the bottom back of your head.

If anyone has a problem with glasses fogging up, fold a tissue in half and place it inside along where the mask fits over your nose. I found it works-I need my glasses on at all times. I think this tip has been mentioned before.

Although I'm not sure where to get chiffon or silk at this point. I just use all cotton-either t-shirts and/or bandanas.

Re: Study determines best fabrics for face masks

Twins Mom — Sun, 10 May 2020 20:22:52 GMT

@CelticCrafter

I guess all quilting fabric same quality? I am currently using two button down shirts that were monogrammed for the school staff. Nice 100% cotton label and when I hold up to light little comes thru. I have been able to make several masks for our family. Other scraps I have I don't know if they have some polyester.

Re: Study determines best fabrics for face masks

CrazyDaisy — Sun, 10 May 2020 20:25:56 GMT

@granddi wrote:
The very best masks are N95 and cost pennies.
Where are they?
Regular citizens should not have to be scrambling to figure out how to protect ourselves.

We all want to open up activities as usual but without adequate personal masks for those who chose to use them, it is not without risks.

Many new outlets are reporting a company in Fort Worth Tx offered to start up production of N95 masks. After over 2 months of back and forth (between Jan and March), they finally have plans to start manufacturing masks. Of course health care workers should get the masks first. But ordinary citizens should be able to access these masks also.

If an N95 mask is important to you many construction supply companies have them in stock.

Re: Study determines best fabrics for face masks

Marp — Sun, 10 May 2020 22:00:02 GMT

Speaking of tightly woven fabric I was going to make a mask from a piece of Kevlar material I have but discovered I couldn't breathe through it.

Re: Study determines best fabrics for face masks

Sage04 — Sun, 10 May 2020 22:05:42 GMT

For me, I use 100% cotton and I also heard that you should take the material outside and if you can see through it, don´t use it. With cotton material, I use two ply with the inside, turn on the wrong side so that the person would be be able to tell which side goes to their face.

Re: Study determines best fabrics for face masks

QueenDanceALot — Sun, 10 May 2020 22:34:57 GMT

@granddi wrote:
The very best masks are N95 and cost pennies.
Where are they?
Regular citizens should not have to be scrambling to figure out how to protect ourselves.

We all want to open up activities as usual but without adequate personal masks for those who chose to use them, it is not without risks.

Many new outlets are reporting a company in Fort Worth Tx offered to start up production of N95 masks. After over 2 months of back and forth (between Jan and March), they finally have plans to start manufacturing masks. Of course health care workers should get the masks first. But ordinary citizens should be able to access these masks also.

@granddi

Even if regular people could acquire them, they still need to be fitted properly to your face. Just being N95 isn't adequate. Not if you are relying on it to be better than a cloth mask.

Re: Study determines best fabrics for face masks

suzyQ3 — Sun, 10 May 2020 23:12:18 GMT

And I've seen several studies that say that polyester or spandex are not very effective as compared to cotton. Mine are triple-layered: the two outer layers a good weight cotton and the inside layer is non-woven polyester (supposedly for good absorption.)

Re: Study determines best fabrics for face masks

GrailSeeker — Mon, 11 May 2020 00:05:46 GMT

I was reading yesterday that the triple folded coffee filter trick (inside a triple folded bandana) is remarkably good, and that paper towels, again used in conjunction with cotton, are even better.

Happy to report also that the task force my son was in are all being sent home, and not one of his unit tested positive after working with covid patients in a field hospital in Detroit . ETA: They wore N95s, face shields, gloves, coveralls, shoe covers, and used lots of handsanitizer.