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With the recommendation from the Centers for Disease Control and Prevention (CDC) that people wear cloth face coverings in public to help slow the spread of COVID-19, many people are buying or making their own cloth face masks. While cloth face coverings are not a substitute for social distancing or N95 masks (these should be left for health care workers), they can help minimize the spread of the coronavirus.
Before you make or buy a cloth mask online (or decide that you can get away with tying a scarf around your face), it is important to know that not all fabrics make for an effective mask. Some options for fabric masks do a better job at filtering virus particles than others. Some barely do the job at all (we’re looking at you bandanas).
We have been providing regular updates on where to buy materials to make your own masks and where to buy quality cloth masks online. Here, I’m breaking down why certain masks and fabrics are better than others, based on research and my own experience (before joining the Reviewed team, I spent years evaluating fabric and apparel, most recently at Nike in product integrity working with our Innovation and Global Apparel Materials teams).
Here are eight things you need to know before buying or making your own mask at home.
1. Some fabrics are more effective at preventing virus particles than others
Fabric has different sized spacing between individual yarns, meaning some fabrics will have larger or smaller “holes” depending on the construction and this will affect their effectiveness against the coronavirus. These holes are where virus-laden droplets or particles can pass through. The smaller the hole the less likely something can pass through, and fabrics such as canvas have smaller gaps and are better to look for material-wise. Masks like these ones from Aplat feature this material and are a great option.
2. Tightly woven fabrics offer better protection
Dense and tightly woven fabrics will also offer the best chance of protection because these have the smallest “holes,” Multiple studies found that tea towels and higher thread count pillowcases offer better protection, the common thread (see what I did there?) among these items is that they’re tightly woven. When buying or making masks look for fabric that is tightly woven like canvas or high thread count sheets.
3. Multiple layers of fabric can increase the effective of the mask
Studies found that multiple layers of fabric increase the effectiveness of filtration of virus particles, but there’s a trade-off—it may be harder to breathe. You want to strike a good balance of filtration and breathability, which is why we recommend looking for masks that have two layers of fabric, like this mask from Hedley and Bennett, though you can always opt for more.
4. A bandana is not the best option
A study from a group of engineers at Missouri S&T tested bandanas, pillowcases, and furnace filters for face coverings. Out of these items tested, bandanas performed the worst. This is not surprising as most bandanas are loosely woven (see #1), which would easily allow aerosols to pass through, so avoid this material if you can.
5. Knit materials tend to stretch and don’t make for the best protection
I would not recommend masks made of t-shirts or any knit materials. Knits are made to stretch and when that happens the holes get bigger, which means it’s more likely that viruses can get through. Stretching on knit materials can happen if a mask is too tight on your face, especially over protruding areas like your nose, or from pulling or tugging on your mask.
A t-shirt type mask might be good for someone who has a harder time breathing. It will offer less protection but a study shows that it was easier to breathe compared to other materials. Knit fabric masks could be used as a cover over a N95 mask for a healthcare worker, as the stretchy material was found to be more comfortable, according to research on the efficacy of homemade masks.
6. Filters are effective but can pose a safety risk
While many masks for sale have an additional pocket for a filter, it could potentially do more harm than good. Certain types of household filters contain fiberglass which can be dangerous if inhaled. 3M has a warning on it website not to use its filters for face masks. Some examples mask filters include vacuum bags, air filters, coffee filters, and unscented dry baby wipes. If you choose to use a filter, it’s recommended to “sandwich” the filter in between the layers of fabric to minimize the inhalation of any fibers. It should be noted that none of these materials have been studied for safety either.
7. The mask should fit snugly to your face
Aside from fabric type, fit is a factor in the quality of a cloth mask. The mask should fit snugly on your face, covering your mouth and nose with no gaps, if possible. Any space between your face and the mask is a potential spot where a virus could pass through.
8. Wearing something is better than nothing
Some people may find wearing masks uncomfortable. If a double-layer tightly woven fabric mask is uncomfortable or makes it hard to breath, try a single-layer, lighter weight fabric or stretchier mask. These may offer less protection than a denser mask, but might be more comfortable to wear. If you don’t have access to materials to make your own mask or can’t buy a mask currently, many household fabric items will offer varying degrees of protection and are better than not wearing a face cover at all.
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Prices were accurate at the time this article was published but may change over time.