- While any type of face-covering made from cotton or another dense fabric lowers the risk of Covid-19, researchers wanted to investigate further
- Silk is not only breathable, but also absorbs moisture well
- Some studies also suggest that the copper in silk may have antibacterial, antiviral properties
As masks are becoming mandatory all over the world, authorities have asked people to use homemade cloth masks instead of single-use surgical and N95 masks that are needed by medical staff.
Face coverings from all materials and shapes are being used. And while all face coverings offer a measure of protection against large and small respiratory droplets, a team of researchers from the University of Cincinnati wanted to examine the efficacy of different household fabrics.
What did their research entail?
The study, which was recently published in the journal PLOS ONE, wanted to determine what practices would be most effective in practice. The researchers examined cotton, polyester and silk by their resistance to the penetration of small and aerosolised water drops.
They also investigated the breathability of the fabrics, and how they would fare if they were washed repeatedly. In the laboratory, they used the materials as an overlaying barrier for respirators, as well as face coverings. The team then looked at the penetration and absorption of droplets – and observed that silk faired the best, both as a barrier and in terms of breathability.
"Cotton traps moisture like a sponge. But silk is breathable. It's thinner than cotton and dries really fast," said Patrick Guerra, an assistant professor of biology at UC’s College of Arts and Sciences.
An antimicrobial material
It’s not only the fact that silk is dense and breathable that made the researchers take note.
Silk contains elements of copper from silk moths, which could contribute to fighting bacteria and viruses. Studies have shown that copper can kill bacteria and has antiviral properties.
"Copper is the big craze now. Silk has copper in it. Domesticated silk moths eat mulberry leaves. They incorporate copper from their diet into the silk," Guerra said.
Silk works as well as surgical masks
The study concludes that silk performs similarly to surgical masks, but have the benefits of being reusable and washable, while repelling moisture. Not only is this better for the absorption of aerosol droplets, but could potentially help minimise mask-related rashes on the face.
"The ongoing hypothesis is that coronavirus is transmitted through respiratory droplets," Guerra said. "If you wore layers of silk, it would prevent the droplets from penetrating and from being absorbed. Recent work by other researchers also found that increasing layers of silk improves filtration efficiency. This means that silk material can repel and filter droplets. And this function improves with the number of layers."
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