MASKS

Mask Manufacturing

Surgical masks are made using specialized machinery, then sterilized. Nonwoven polypropylene and textile material is fed from bobbins into machinery that cuts and ultrasonically welds it together. Surgical masks typically have one layer of textile material surrounded by other layers of nonwoven material on both sides, making for 3-4 layers total depending on the mask. The machine attaches other parts like ear loops or metal strips before the masks are sterilized and packaged.
For cloth masks for personal use,
Cloth masks have become a highly needed product all around World . as the coronavirus pandemic has spread. Technically surgical masks and N95 respirators are also cloth masks, but they are made from special nonwovens with specifically engineered capabilities.
How Effective Are Cloth Masks?

Cloth masks are not as effective as surgical or N95 masks, but they still provide a level of protection for lower risk applications. It’s important to note that masks from woven cloth are not meant to protect the wearer from outside viruses. Like surgical masks, they are used to help stop the spread of viruses from the wearer, which can travel in droplets of moisture produced from sneezing or coughing. They can also help users to avoid touching their faces, which is one of the most common ways of getting infected.

Unlike surgical masks, however, cloth masks are not as efficient at filtration. In fact, the World Health Organization recommends that healthcare workers not use cloth masks. This is because their work exposes them more to the virus, so a higher level of protection for them and those around them is necessary. However, cloth masks still provide more protection than no mask at all according to one study in the U.K., which is why they are recommended for certain lower risk situations.

It’s important to note that no cloth mask will protect the wearer completely without additional precautions. In public spaces, this includes staying six feet away from other people, not touching your face, and washing your hands frequently. In medical situations, this include additional PPE such as gowns, face shields, and gloves.

Who Should Wear Cloth Masks?

The C.D.C. recommends cloth masks be worn by consumers in public areas, especially in areas strongly affected by the outbreak. However, because there have been such severe shortages, hospitals and other medical facilities have had to use cloth masks when they’ve run out of other options (the C.D.C. allows for this when there is no better method of protection). Medical facilities have also been using cloth masks for patients and nonmedical staff who don’t come into contact with patients.

It’s important that users remove cloth masks without touching the front, and avoid touching their eyes, nose, or mouth while they’re doing it. Masks should be washed each time they’re used (a hot washing machine can kill the virus), and as soon as the mask is off, the user should wash their hands.

What is the Best Cloth for Masks?

There hasn’t been much research on how effective types of unconventional fabrics are for masks, so many scientists are hesitant to advocate for one type over another. However, many medical facilities asking for cloth masks have requested tightly woven cotton masks, and the Los Angeles Mayor’s Office has asked companies offering cloth masks to make them from latex-free cotton or cotton blend materials. Cotton (preshrunk before being sewn) is preferred because there are indications synthetic materials like polyester allow the virus to survive longer. There is also a study that showed it has higher filtration efficiency than several other types of cloth, including linen and silk. Cotton does have a drawback, however, in that it has been shown to retain moisture which can lead to bacterial growth. Masks of this kind should be washed frequently to avoid this problem.

Another potential material recommendation is nonwoven fabric meant for less specialized applications, such as shop towels. Peter Tsai, the inventor of the electrostatic process for material used in N95s, has recommended using the towels since they are sturdy enough to be washed and reused, and they filter more than cotton. Shop towels can also be combined with cotton to augment its filtration.

Whichever material is used must both filter and be breathable, and there will be a trade-off between how well it filters and how easily the wearer can breathe. Some of the most breathable nonwovens, such as paper towels, have little ability, while some nonwovens with good filtration ability, such as vacuum bags, are very difficult to breathe through. The less breathable a material is, the more difficult the mask will be for those who have breathing problems. It also makes it more likely users will take the mask off or avoid wearing it, causing greater risk for infection.

Mask Design Considerations

There are dozens of open source mask designs floating around on the internet, and like materials, there is no current consensus for which type of mask design is most effective. However, the C.D.C. and other organizations have made some recommendations to ensure the mask provides as much protection as possible.

  • Fit. A mask should fit snugly but comfortably to the sides of the face to avoid large gaps between the mask and face. It should provide enough coverage to go below the user’s chin and up the bridge of the nose.
  • Fastening. Ties or elastic ear loops are the most commonly used, although ties may provide a better fit.
  • Layering. Multiple layers of fabric make it more difficult for foreign matter to get through. This can involve making the mask with multiple layers or creating a place for an additional filter can be inserted. One coalition of clothing manufacturers is making triple layer masks with an antimicrobial finish, although there are no studies on how effective antimicrobial materials are.
  • Breathability. The wearer should be able to breathe without too much effort. This is especially important for people with breathing problems. However, even those without those problems will be more likely to take the mask off and get infected if breathing is too difficult.
  • Washability. Unless it’s disposable, the mask should be able to go through repeated washings without getting damaged, shrinking, or changing shape.