How to improvise a face mask from HEPA Vacuum Bag Filters

Susan Saxe
Mar 22 · 8 min read

IMPORTANT UPDATE 3/30/20202: I have no special status or expertise, but I have been tracking this DIY mask-making thing to the best of my ability. The latest information I have is that in most cases it is not possible for people to sterilize HEPA Filter material for reuse because the only known, tested way to do that without damaging the fibers is with powerful UV light equipment that even most hospitals don’t have. Some healthcare and frontline people are putting HEPA filter material inside cloth masks as an added filtering layer and just reusing it, washing the cloth masks inbetween. (This entails some risk in the process of handling the contaminated mask materials, so leave that to trained personnel.) In light of that, it may make more sense if you have HEPA vacuum bags on hand to offer them whole to people who might want them, rather than cut them up and sew them into masks. Ideally the material could be cut to spec and stitched around the edges to hold the layers together, but that would have to be done in a sterile environment, so that may not be practical for the home DIYer, though I suppose you could cut and stitch the material and they could keep it in quarantine for several days until any potential germs die off by themselves.

We are in uncharted waters and under normal circumstances it would be unthinkable to even try these hacks. So, before you go any further, check with local frontline people and see what if anything they want you to do. Minimally, those at risk have the right to make their own decisions about what they want to try to do to protect themselves.

Some frontline workers are still asking for cloth masks, sometimes with a pocket to insert whatever material they think might help them protect themselves. (I’ve heard of some workers repurposing the wraps that sterile instruments come in as a filter layer.) Sometimes hospitals are using cloth masks in areas of the facility where they don’t think there is as great a chance of covid contamination, and rationing the N95s for workers at greater risk. Sometimes they put them on patients to keep their droplets contained. Let’s let the experts make the calls and just support them as best we can.

Meanwhile…cloth masks continue to be better than nothing for regular people to wear as a public health measure, to keep their germs to themselves instead of coughing, sneezing, breathing and inadvertently scattering droplets on other people or surfaces. They may also, if breathable and worn tightly, provide some protection to the wearer. Some protection is better than none. So, by all means, keep stitching and distributing those cloth masks. Let’s bend the curve.

Another caveat: Some people are posting directions to make masks out of material other than cotton, polyester or cotton/poly blends, like bras, etc. NO NO NO! Please don’t do this, and please do warn others not to do it either. This can be dangerous for a variety of reasons including that these materials may not be “breathable” enough, causing the wearer to suck in unfiltered air through the sides of the mask and then accumulate it around their nose and mouth. Instead of protecting people, these devices can become traps and breeding grounds for germs (corona or otherwise) providing a warm, moist place for them to grow. And they create the illusion of safety that might cause people to take risks they would not take without the mask. NEVER do that. Stay safe out there.

Ok, back to the original directions if you still want them:

Hi, volunteer stitchers. These are detailed, step-by-step instructions for home manufacture of face-masks for use by frontline workers or people who have to care for infected or possibly infected people at home. Some experts I have consulted think they will work, but they are NOT lab tested and are not a substitute for genuine N95 masks if those are available. These are only for use as an emergency measure, and can only be reused if properly sterilized between uses, or at least between shifts for those working in institutional settings.

A word about masks in general: If you are asymptomatic and just observing quarantine to help “bend the curve,” you probably don’t need more than a cloth face mask if you must venture outdoors. This is mostly to protect others from your droplets though it may also give you some protection. If you have symptoms, obviously, just stay indoors and away from others as much as possible, and mask up around those in your house. There are many videos and instructions on line for making a wide variety of masks out of materials that many people have on hand. This is a good one for cloth face masks (Ignore the claim about hospital use.): https://www.youtube.com/watch?v=TL9D6ZFtZHM These can be reused by just washing them with soap and water or running through the washer and dryer. There are also patterns and videos for masks with a pocket for inserting additional filtering material. I do not recommend these for use by anyone but a trained professional who can properly observe protocols for safe use and sterilization. If you make these, please do so under the direction of someone who knows what they’re doing. Under no circumstances should a mask, particularly an improvised one, tempt you to take any chances you would not take without a mask. Let’s stay safe.

Now, on to making those HEPA Filter masks.

Definition: A “HEPA” Filter is a High Efficiency Particulate Air Filter. It is made from specially woven and treated fibers that filter very tiny particles out of the air. Many vacuum cleaners use HEPA Filter bags and these are what we will take apart and use for our masks.

NOT ANY VACUUM BAG WILL DO. Look for the HEPA label, stating that it is 99.97% effective for particles up to 0.3 microns. Bags that claim to filter out allergens are not suitable, as dust and pollen particles are way bigger than viruses.

MATERIALS YOU WILL NEED:

HEPA Filter Vacuum Bags. These may be available at hardware, home repair and appliance stores, etc. Only get what you will actually sew. Don’t hoard.

¼” elastic or something like it. Round elastic will do, as will string or ties that you can sew from bias tape or strips of fabric. I don’t recommend rubber bands because they might break at the wrong moment. Improvise as best you can.

Small paperclips for the top of the mask to shape it to the nose

A sewing machine

Thread (colorful is good because it’s easier to see what you are doing.)

Cutting tools. Can be just a ruler and scissors or a quilter’s rule, board and rotary cutter.

Something to measure with — cutting board, ruler, even a piece of lined paper

Some pins

A seam ripper or other sharp tool to make small holes in the material for the nose wire

Felt marker

Steps:

1. Preparing the material: Take the vacuum bag out of the package and unfold. Cut off the fused short ends of the bag so that it can be opened out into a tube. Flatten out the tube so that the fused long sides can also be cut off. You will now have two sheets of HEPA Filter fabric, one of which will have the plastic or cardboard valve in the middle of it. Carefully remove the valve and discard. You will notice that the two sides of the fabric are slightly different. This is purely conjecture on my part, and the masks may be equally effective inside out or outside in, but the way the vacuum bag works is that it sucks in particles and then prevents them from escaping through the HEPA fabric. So you want to treat the user like they are on the outside of the bag, trying to not be infected by what is inside the bag. Therefore, put the softer, cloth-like outer side of the bag toward the face to keep the particles away from the wearer. An infected or possibly infected person could wear it inside out, to keep the particles in. Just my guess, but if you wear it inside out, move the paperclip to the other side of the casing so you don’t get poked.

2. Cutting your mask pieces: Measure your material and cut as many 7”x 10” pieces as you can get out of the bag. That will vary depending on the model and size of your bag. (If you have a piece left over that is less than 7x10 but not too small, you could make a child-sized mask out of it.) You may want to put a pin in the middle of each side to keep the layers together if you are a beginner.

3. Sewing the top and bottom hems: Fold over the long sides to about 1/2” and pin them. Stitch them closed, about ¼” from the folded edge. Then turn the piece around and zig zag over the raw edge to reinforce and stabilize. Do both top and bottom before proceeding to sides.

4. Making the pleats: Form 3 pleats along one short side, and pin them. Pleats should be about ½” deep (meaning take a ½” pinch of fabric and fold it over), evenly spaced and all facing in the same direction. Repeat along the other side, making sure they are all going in the same direction as the other side, and pin.

5. Stitch over the pleated ends with a straight stitch, removing pins and adjusting as needed to get an even edge.

6. Cut two 10” pieces of elastic. Lay one piece about ½” from the pleated edge, with both ends sticking out about equally, and fold the edge over the elastic. Stitch the edge closed, being careful not to catch the elastic in the seam. Then turn the piece and zig zag over the edge as you did on the top and bottom. That will form a casing through which the elastic can slide to fit the face when used. Repeat on other side. Now you have the basic mask.

7. Tie off the elastic to make the loops that go around the ears, by putting both ends together and then looping them both through themselves to form a knot. Don’t use a square knot or granny knot as it might come undone.

8. Adding the nose piece: Decide which will be the top of the mask and fold it in half, right side out. Insert a pin to mark the center. Now open it back up and put it up against a measure. Using your felt marker, make a dot in the middle of the hem/casing on either side of the pin about 1/2" from center. Make two more marks at equal distance from the first mark on each side, so that there is a symmetrical pattern of 6 dots, 3 on each side of the center. These will become the holes for inserting the paperclip/nose wire. Take the sharp tool and make small holes in the middle of each dot. Straighten out a paperclip as best you can and thread it through the holes so that it is centered at the top of the mask.

9. Congratulate yourself for making the mask and find it a good home.

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Susan Saxe

Written by

I’m a lifelong radical activist, intersectional in outlook since back in the day when we just expressed it as the idea that “everything is connected.” It is.

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