Fashion designers looking for a more effective way to reinforce the filtration capabilities of homemade face masks discovered after a battery of testing that blue shop towels might be the best bet for now.
California’s Suay Sew Shop co-owners Lindsay Medoff and Heather Pavlu, along with Medoff’s high school best friend, designer Chloe Schempf, are recommending that people making homemade face masks should try lining them with polyester hydro knit shop towels as a way to increase the filtration rate of cotton masks.
Schmepf told Business Insider that she was appalled by the concept of the CDC’s mid-March recommendation that desperate healthcare workers without access to face masks should use cotton bandanas as a last resort.
Suay Sew Shop co-founders and a designer friend tested multiple fabrics for their particle filtration properties, while looking for materials to enhance the capabilities of the masks they’re making to donate at their factory (pictured)
The company is making thousands of PPE masks which they will be donating to people in need
‘The recommendation of a bandana made me ill,’ Schmepf 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%.’
She, Medoff and Pavlu decided to see if they could find easily-obtainable materials that would provide greater filtration against droplets and coronavirus particles than just plain cotton.
Schmepf said that they came up with a list of materials ranging from coffee filters and Swiffer dusting clothes, to window shades and even material used in aviation, oil refinery and the medical fields.
Suay Sew Shop CEO and co-founder Lindsay Medoff
They then bought a $1,400 Grainger particulate-counter device capable of measuring filtration down to 0.3 microns.
N95 masks – which hospitals are desperately in need of – effectively block about 95 per cent of particles that are 0.3 microns or larger.
The women then spent 10 days using the device to test every fabric they could get their hands on, specifically seeking out a material that was easy to buy, had good filtration, but was also breathable.
The combination meant that things like HEPA vacuum-cleaner bags were left by the wayside, as they were too suffocating to use as a face mask, even though they had a high filtration capability.
However, Arizona doctor Ryan Southworth posted a video on YouTube on March 20, suggesting that homemade masks made with HEPA filters would be a good contender for people looking to make masks to donate to emergency medical workers.
One material that the designers they found that proved to have all the elements they were seeking, were blue shop towels, the kind usually sold at hardware and automotive stores.
The towels are made of a polyester hydro knit, an absorbent material that’s particularly good at cleaning up oil, grease and other liquid spills.
The designers said they also found another material – a towel made of polypropylene – also worked well, but don’t recommend it for regular mask makers as it’s hard to get. They are lining the masks they are producing with the material
The designers spent $1,400 to buy a machine that can test fabrics for particle filtration levels
Their testing indicated that ToolBox and Zep shop towels had higher levels of filtration than other blue shop towels
The designers found that lining a cotton mask with two blue shop towels enhanced the mask’s filtration rate up to 93 per cent when it came to 0.3 micron-sized particles.
Cotton masks alone, they found, filtered only 60 per cent of those size particles, Schmepf told Business Insider.
The two brands they tested and recommended were ToolBox’s shop towel and ZEP’s industrial blue towel. The also tested Scott-brand shop towels, but found they weren’t as effective for filtration as the other two brands.
They are still testing the other shop towel brands on the market.
During their general material testing, the women also identified another fabric with solid filtration capabilities – towels made from polypropylene, which is used to clean industrial machines.
According to their tests, the masks made from this material held 95 per cent of their filtration abilities for up to three machine washes, making them ‘semi-disposable’ masks.
Suey Sew Shop CEO Medoff said that her company brought enough of a supply of the material to make 200,000 masks that they will be donating to healthcare and essential workers or the elderly or people with pre-existing health conditions that need personal protective equipment (PPE).
So far, the Suey Sew Shop – a 30-person boutique clothing manufacturer – said it has already produced thousands of masks, with the aim of making 10,000 per week.
Medoff said that although the material works well, she isn’t recommending it for regular people to try to get because the companies that produce the material are now focusing on making medical-protection supplies.
The designers are now intent on finding a way to test both the blue shop towel-lined and polypropylene masks to see if they are capable of blocking the COVID-19, coronavirus pathogen, which is smaller than what they can test with their machine.
Schempf has started a GoFundMe to raise the $40,000 they need to have their masks tested at a Kansas City lab that makes COVID-19 testing kits, as well as to help fund production of masks in her Michigan hometown.
Suey Sew Shop’s GoFundMe has already raised more than $113,000 for its production of the masks.
Despite their own testing, the designers said that they don’t have any proof yet that either of the materials will healthy people against coronavirus any better than an ordinary cotton mask will.
However, they believe that masks made of less permeable material that cotton can only increase a face mask’s effectiveness.
They also said that the fit of masks was incredibly important.
‘The fit has a lot to do with your protection,’ Schempf said, adding that ‘You can have a great mask, but if you aren’t getting a tight fit, it won’t protect you.’