How to make or buy a COVID-19 face mask that actually works

Although cloth masks provide only minimal protection against the spread of COVID-19 and other viruses, the Centers for Disease Control and Prevention (CDC) now recommend that everyone use them when leaving the house. The hope is that this low-risk, relatively easy intervention can make a dent in the spread of COVID-19 by people with no symptoms or extremely mild ones.

But masks aren’t exactly easy to come by: Medical-grade ones are already in short supply for healthcare workers who need them, so healthy people shouldn’t even try to purchase them. And in the wake of the CDC’s new recommendations, even non-medical cloth masks are sold out or backordered in many online stores. If you’re trying to figure out if and how you should cover your face on your next essential trip out of the house—for a walk on an uncrowded street or to buy necessary groceries, for instance—here’s a guide to all your options.

Things to look for and avoid when buying a cloth mask

Lots of crafters and makers, as well as companies that usually sell other fabric products, are now offering non-medical masks for sale. But not all of these masks are created equal. If you’re ordering protective equipment online, here’s what to look for:

• Do not buy medical-grade, filtering masks unless you are immunocompromised or are caring for someone sick with COVID-19. Hospitals are experiencing extreme shortages of these masks, and they are not shown to provide significant protection for healthy individuals.
• Your mask should cover your nose and mouth and should have fastenings that keep it firmly in place while you talk, move, and breathe. If you have to touch your face to adjust your mask, you risk exposing your nose or mouth to germs.
• Ideally, the mask should have some kind of adjustable band to minimize gaps between your nose and your cheeks.
• The most effective fabrics are water-resistant and tightly-woven—not stretchy or sheer. A tightly-woven cotton is the next best thing, and your mask should have at least two layers of it.
• Your mask should be easy to sanitize by boiling or throwing in the washing machine. That means it shouldn’t have fabric glues, delicate materials, or funky decorations (other than prints on the fabric). Embellishments like sequins (yes, there are people selling sequined masks right now) provide surfaces that viral particles can linger on for days.
• If you buy a fashionable cover to go over your mask—some stores are selling glittery fabric covers and chainmail overlays, for example—remember that this outer layer is being exposed to viral particles. You must remove it and sanitize it just like you would with the mask itself.

What about a balaclava or scarf?

Rachel Noble, a public health microbiologist at UNC at Chapel Hill, tells PopSci that balaclavas and other warm-weather gear designed to cover your nose and mouth are unlikely to be suitable for preventing the spread of COVID-19. Because they’re designed to be as easy to breath through as possible, they tend to be made of loose fabrics.

“You want to choose a really, really tightly woven fabric,” Noble says. “We’re talking about something that’s approximately the density of the weave of a bandana, or a really high-quality bedsheet.”

Jersey fabrics, towels, and any textiles that stretch when you pull them are likely too loose, she says, as are most sweaters and other knit yarns. So if you really can’t sew or put together a mask with hair ties as described below, covering your nose and mouth with a bandana tied around your face is probably slightly more effective and easier to sanitize than a balaclava or wound-up scarf. But all of these workarounds are mostly only beneficial in that they remind you not to touch your face and shield bystanders from the worst of your coughing and sneezing. If you’re coughing and sneezing, you should really be staying inside.

DIY mask: If you have sewing supplies and a non-woven polypropylene reusable grocery bag

Back before the CDC expanded recommendations, PopSci did a deep dive into the most effective DIY mask design. Our tutorial utilizes a fabric commonly found in free reusable grocery bags and doesn’t require a sewing machine. Based on our reporting, this is about as effective as a DIY, non-medical-grade mask can get.

DIY mask: If you have sewing supplies and cotton fabric (like an old t-shirt)

If you don’t have any non-woven polypropylene fabric to work with, a tightly-woven cotton is your next best choice. You can follow our no-sewing-machine mask tutorial using two layers of tight cotton in lieu of the more effective hydrophobic fabric. The best fabric scraps to use would be stiff, 100-percent cotton textiles like bandanas or high-quality bed sheets.

DIY mask: If you can’t sew but have a t-shirt to cut up

The CDC has a quick tutorial for cutting a t-shirt into a no-sew face covering. This tutorial, however, leaves you with a single-layer mask, which is not ideal. At the very least, you’d want to wear two of these masks together, secured as tightly as possible. If you have a needle and thread and can learn to do the most basic of stitches, you can attach those two layers together and add a pipe cleaner or twist tie as an adjustable band to make the mask more effective, as described in this tutorial.

DIY mask: If you can’t sew but have a bandana or t-shirt and two hair ties (or some socks)

These easy instructions yield a mask using just a bandana and a pair of hair ties. You can also substitute other squares of fabric—old t-shirts in tight cotton weaves or sliced-up sheets that aren’t stretchy—and use cut-up socks or leggings if you’re short on hair ties. Because these masks leave gaps around your nose and cheeks, they’re much less effective than masks with adjustable nose bands. You can tuck a pipe cleaner or plastic twist tie into the top portion of the mask to make it mold more tightly to your face.

How to properly remove your mask

Whatever mask-ish item you buy or make, one thing is crucial: Once you get back into your own home, treat the fabric as if it’s contaminated with viral cells. If you touch the outside of your mask—which has been exposed to any of the aerosolized droplets it’s protected you from—and then touch your face or objects around your home, you may put yourself at even greater risk of exposure than you would by simply walking around bare-faced. The point of wearing a mask is protecting other people from your germs, but that doesn’t mean it can’t end up being a vector for COVID-19 from strangers’ sneezes.

This guide explains how to remove different types of masks without touching the contaminated outer surface with your hands or face. Designate a receptacle for storing dirty masks and wash your hands with soap and water for 20 seconds once you’ve tossed a used one in.