Here are the instructions for a better-fitting homemade mask that can filter particles 2x better than cotton, created by three clothing designers
Julie Bort Business Insider•April 13, 2020

Suay Sew Shop thousands of surgical masks
Suay Sew Shop making thousands of their own design of surgical masks from industrial fabric

Three fashion designers have created a new homemade, surgical-style mask and are giving the pattern away for free.

Their design includes a pocket that can be filled with a material to help the mask filter tiny particles better than a mask made only from cotton, according some testing that they did.

After testing dozens of materials with rented particle-testing equipment, they discovered that certain blue shop towels, as well as a certain white industrial cloth, can help a homemade cotton surgical mask filter particles 2-to-3x better than cotton.

Their testing also showed that the fit of the mask was crucial to having it filter particles well.

So they designed a new mask for the legions of home sewers making masks right now.

This is not an FDA-approved N95 mask but is intended to be a better-fitting alternative to some of the other patterns for surgical masks circulating on the internet.

 Three fashion designers created a homemade, surgical-style mask that can filter particles better than a typical cotton mask, according to their home particle testing, and they're now giving away the pattern and instructions for free.

Their new design uses a cotton shell and allows the sewer to add another layer into the mask to act as a filter, either by sewing the filter as a lining or by adding a pocket into the mask and putting the filter material into the pocket.

The designers spent days testing dozens of materials and found that polyester hydro-knit, found in certain brands of blue shop towels, worked best, and could filter particles twice as well as cotton. They also found that a fabric called polypropylene, used in a certain type of white, oil-absorbing shop towel, works well too.

Business Insider originally wrote about this project earlier this month and the designers — Lindsay Medoff, the CEO of boutique Los Angeles clothing manufacturer Suay Sew Shop, along with her business partner, Heather Pavlu, and her best friend from high school, Chloe Schempf — have since received an outpouring of support for their project, they say.

They have now posted instructions and the pattern as a downloadable PDF on Suay's and Schempf's GoFundMe pages (which are raising money for professional mask making in LA and Michigan respectively).

The designers created the mask after testing dozens of fabrics with particle-testing machines that check for particles as small 0.3 microns. The coronavirus that causes COVID-19 is smaller than that. However, the CDC is recommending that everyone wear some sort of mask in public, even a bandana, to help stop the spread of the disease, since any face mouth covering can block droplets that could carry the virus. The designers' goal was to find fabrics that people could buy as easily as cotton and that balanced filtration with breathability.

After testing everything from vacuum cleaning bags to commercial fabrics, Medoff, Pavlu, and Schempf discovered that stretchy blue shop towels made from polyester hydro-knit seemed to meet many of their criteria. It should be noted that this is not an FDA-approved N95 mask but is intended to be a better-fitting alternative to some of the other patterns for surgical masks circulating on the internet. (For the full details on how they went about their testing, read the original story: Using blue shop towels in homemade face masks can filter particles 2x to 3x better than cotton, 3 clothing designers discover after testing dozens of fabrics.)

A new option with a pocket

A Suay employee models the blue shop towel mask

Suay Sew Shop

Some experts are concerned that wearing unusual materials directly on your mouth as a mask could cause skin irritation or cause tiny particles of the material to be inhaled. That's why, in their latest design, Medoff, Pavlu, and Schempf created two versions of the mask.

One version sews a filter lining directly into the mask. The second version adds a separate pocket for filtering materials. That designs allows someone to use a shop towel for filtration without putting it in direct contact with their face. The masks with a pocket can also be hand-washed and line-dried, while the masks with a filter lining cannot.

By adding a pocket to the tight-woven cotton mask and putting in two layers of shop towels, their tests showed the mask consistently filtering out 82% of particles, although some of their tests showed it filtering at an even higher level. Filtering depends on many factors, including the mask's fit on the person.

To improve fit, their design includes a wire nose piece that keeps the mask snugly in place, elastic trim, and other sewing techniques. So, even those who don't want to add a filter to the mask may want to use this homemade mask design for its fit.

The materials the designers recommend for their mask design are:

Tight-woven cotton like quilter's cotton, tight woven muslin, or old twill pants to make the mask's shell.

For the optional filter, the designers had the best test results with these three brands: Wypall X80 Towel, Zep Shop Towel, Toolbox Shop Towel. It's worth noting that the makers of the shop towels have not approved their towels to be used as masks, do not warranty masks made from them, nor do they recommend that their towels be used as a mask.


They also tested the Scott Shop Towel brand and while it worked better than no filter, it didn't work as well as the other mentioned brands (it filtered out 70% of particles versus 82%)


Another option for a filter is the oil absorbent towels that Suay, a commercial clothing company, was able to buy in bulk, though it's not as easily obtained by the public.


Using blue shop towels in homemade face masks can filter particles 2x to 3x better than cotton, 3 clothing designers discover after testing dozens of fabrics
Apr 2, 2020

Lindsay Medoff, the CEO of Suay Sew Shop, a 30-employee boutique Los Angeles clothing manufacturer, wants the armies of people sewing homemade surgical masks to add a specific blue shop towel inside them. 

Medoff and two friends were appalled by the dozens of mask patterns calling for cotton, a highly breathable, permeable fabric, and became obsessed with finding a fabric better suited for the job. They built a homemade testing facility that could test particle filtration down to 0.3 microns and tested every fabric they could find, from coffee filters to industrial materials.
They discovered that by adding two blue shop towels and using a design that produces a tighter-fitting mask, they could make a mask that could block up to 95% of the particles they could test, while the cotton masks blocked 20% to 60% of the particles. 

These are not meant to replace the N95 masks worn by healthcare workers — they're designed to be an alternative to the cotton masks that many people are making and wearing for quick trips to the grocery store. 

The women are sewing about 200,000 masks (or until their own supplies run out) and giving them — and a design — away, as well as raising money to pay their workers their full wages. 

They're also raising money to get their mask tested with the actual COVID-19 pathogen to see whether their design could be validated as a safer solution during the mask shortage.
"This is ordinary people taking their power back," Medoff said. 

The US boutique clothing manufacturing industry is abuzz as sewing shops retool themselves into surgical-mask-making factories, like something out of a World War II "it's up to you"-style poster.

Lindsay Medoff, the CEO and owner of Suay Sew Shop, a 30-employee boutique manufacturer in Los Angeles, has eagerly jumped on board. But when she got a mask pattern from an ER-doctor friend of hers a couple of weeks ago, she was shocked.

"They sent me a pattern that looked like [it was] from Etsy," she told Business Insider. "I thought, 'What do I do with this?'"

Suay's fashion niche is industrial upcycling, a big fashion trend these days. The company takes unsold clothing items from major brands, such as Patagonia down vests, and crafts them into new clothing, recycling 85% or more of the materials.

But the mask instructions circulating on the internet are not geared toward professional, industrial production. Pro shops use digital instructions, not the kind of paper patterns people buy from fabric shops like JoAnn, Medoff said.

Medoff called her best friend from high school, Chloe Schempf, who also sews and previously had a career designing displays for fashion brands like Urban Outfitters and Free People. Today she's a full-time mom living in rural Michigan, where her husband's veterinary practice is. (Her husband, Dr. Ray Harp, is a cast member on the long-running National Geographic show about country vets, "The Incredible Dr. Pol.")

Schempf had dusted off her sewing machine to join the troops of homemade-mask makers, but when she looked at the instructions, she had another surprise.

No one seemed to be thinking about the fabric that the instructions called for: cotton, and cotton fill for the filter.

How could a highly breathable cotton weave be the right material to filter microscopic pathogenic particles?

Then Schempf saw that the Centers for Disease Control and Prevention was telling healthcare workers unable to get proper gear to use a bandana as a last resort.

"The recommendation of a bandana made me ill," Schempf said. "I couldn't understand how we can go from a 2020 N95 mask to a 1918-era cotton mask with a variable filtration of 20% to 60%." 

3 women set up their own mask-testing shop

Clothing is all about choosing the right fabric for the right use. We don't use insulated down-filled fabric for a swimsuit or a T-shirt jersey knit for a winter coat. If a cloth mask is all that people have access to, then the CDC recommends using that and these clothing designers are not medical professionals and have no reason to contradict that advice.

Still, a few weeks ago, before the CDC recommended cloth masks, Schempf, Medoff, and Medoff's business partner, Heather Pavlu, a co-owner of Suay Sew Shop, became obsessed with finding a less permeable fabric for masks.

Suay Sew Shop's Heather Pavlu testing mask particle filtration in the lab she and her friends built. Suay Sew Shop"We spent a few days researching and brainstorming any material that could filter: coffee filters, batting, window shades, Swiffer, interfacing, etc., all the way to more technical materials that are available to specialized industrial sectors like aviation, oil refinery, medical fields," Schempf said.

They bought a $1,400 particulate-counter device from Grainger that measures filtration ability down to 0.3 microns and spent another 10 sleepless days testing all the fabrics they could find.

They wanted a material they could buy as easily as cotton but that balanced filtration with breathability — they discovered that HEPA vacuum-cleaner bags, for instance, had great filtration but were too suffocating to wear.

The ideal material turned out to be stretchy blue shop towels made from a polyester hydro knit.

Inserting two of these towels into an ordinary cotton mask brought filtration up to 93% of particles as small as 0.3 microns, the smallest their machine could test. Meanwhile, the cotton masks filtered 60% of particles at best in their tests, Schempf said.

Polyester hydro knit towels are readily available at hardware and automotive stores. The two brands they tested were ToolBox's shop towel and ZEP's industrial blue towel. Interestingly, Scott's pro shop towels, which are also made with a hydro knit fabric, didn't work as well, Schempf said.

The team is continuing to test other brands.

ToolBox shop towels. Harbor FreightHaving found the material, they worked on a design. "The fit has a lot to do with your protection," Schempf said. "You can have a great mask, but if you aren't getting a tight fit, it won't protect you."

Pavlu said she sewed "at least 15 types of the patterns that were being spread on the internet" before the team realized they were going to have to design a new mask themselves.

So Pavlu tracked down and rented a PortaCount Respirator Fit Tester 8040 machine, and the team tested things like how a wire nose clamp could help create a high-filtration, one-size-fits-all mask.

They are putting the final tweaks to their mask design and plan to release the design for free to the public next week. The instructions will be good for home sewers and pros, available on Suay's website and its GoFundMe page.

200,000 masks from an industrial material

During their tests, they discovered another material that filtered exceptionally well: cleaning towels made from a plastic called polypropylene, used to clean industrial machines.

 

Suay Sew Shop's homemade fabric-testing lab. Suay Sew ShopSuay bought a big supply of it. But the team can't recommend this fabric to the public. The supply is dwindling, Medoff said, because the industrial makers of the material are now dedicating themselves to manufacturing medical-protection supplies.

till, Suay believes it has enough to make about 200,000 masks and has already sewn thousands, Pavlu says.

The team also discovered the mask held 95% of its filtration abilities after up to three machine washes.
"We are calling them semi-disposable at this point and are continuing testing after six, seven, 10 washes," Pavlu said.
Schempf believes the next step is to test this mask and the shop-towel version to see whether they actually block the COVID-19 pathogen, which is a smaller particle than their equipment can test.

They are curious and hopeful about their masks, but they don't have any proof that they will protect healthy people from getting the virus any better than an ordinary cotton mask.

Health experts have said that while surgical-style masks like these aren't likely to protect a healthy person from getting the virus, if people with COVID-19 wear them — especially along with following social distancing — that could help minimize the spread.

Schempf said she found a lab in Kansas City making COVID-19 testing kits that was willing to test their masks, but the testing fee is $40,000. She's started a GoFundMe to raise the money and to fund mask-production efforts in her area of rural Michigan.

How masks can help

Medoff said that the shop-towel masks and the ones from polypropylene fabric that her staff is making are not foolproof safety measures. The logic is that if even cotton masks are useful, then ones made of less permeable material can only help.

Suay is in full production and giving the masks away to anyone who needs them, including medical professionals, nursing-home workers, hospice-care workers, people caring for an ill relative, and grocery-store workers — people who are "risking their lives" on the front lines, she said.

 

Suay Sew Shop's masks. Suay Sew Shop

Many of these people break down in tears when they get these masks, she said.

Because she's paying her workers their full wages to sew the free masks, and materials and labor costs are intensive, she's asking for donations via a GoFundMe.

"This is by community, for community," Medoff said. "This is ordinary people taking their power back."