Introduction: MOO MASK: a No-Sew Mask to Reduce the Spread of COVID-19

IMPORTANT UPDATE: Please visit for the latest information on MOO MASK. You'll find the latest information on materials and additional tips on making and using MOO MASK.

There's been a lot of news lately about the shortage of protective equipment for healthcare workers during the virus pandemic, and especially the shortage of N95 masks. Lots of folks are sewing cotton masks, but since not many people sew anymore, I wanted to create a mask that could be made out of easily available materials and that didn't require any special skills or tools, and that would hopefully perform nearly as well as one of these manufactured N95 masks.

After a few evenings of tinkering, I came up with MOO MASK. It’s a silly name, but I think it looks a little like a cow's nose. The video describes the process in some detail, and there's additional information at my website,

Please note that MOO MASK has not been tested or certified to be safe or effective. It is to be considered a last resort when proven alternatives are not available. Use at your own risk. Please visit for further information.


The mask is made from the filter fabric out of a furnace filter, a few staples, a couple of rubber bands, a small piece of wire, and a bit of duct tape. The tools are likely things you already have around: a utility knife, a straightedge, a marker, a wire cutter, and a stapler.


There are few different kinds of furnace filters that you can buy. We're looking for the kind that has a white, pleated polyester fabric in sort of a cardboard frame. There are different brands and different sizes; the width and height of the filter aren't critical, but the masks will be easier to make if the thickness is 5", but 4” will also work.

This furnace filter is 20" x 25" x 4". I spent about $25 on it, and it will yield enough material for about 45 masks. They're not hard to find. They're available at most hardware stores. If you can't get out to shop, you can order the filter (and the other supplies) online.


Furnace filters are rated according to a MERV number, which is an acronym for "Minimum Efficiency Reporting Value." That number just indicates how efficiently the filter removes contaminants from the air. We're looking for a MERV 11 filter, which is towards the high end of residential filters. The packaging for the one I'm using here says it’s effective against 95% of airborne particles from 0.3 to 10.0 microns. I think that puts this fabric in the same ballpark as the material used in N95 masks.

The highest rating that you're likely to find in a residential furnace filter is MERV 13; those are advertised as being effective against 99% of particles down to 0.3 microns, rather than 95%. I tried making some masks with the MERV 13 fabric, too, but it was a little too difficult to breathe through.


Taking the filter apart to get at the filter fabric is pretty straightforward. I've had good luck with cutting around the end of each box, about an 1/8" from the edge, and removing the ends.

The ends of the pleats are glued to the box, so some patience and a little time with a utility knife will liberate it.

There's a wire mesh that's lightly bonded to the fabric to help it keep its shape. Once you've got the fabric out, you can strip that mesh right off.


The fabric for each mask is a simple 8" square, cut from the larger piece out of the filter. Cut the fabric so that one of the pleats is running straight through the middle of the square.

The filter fabric has a smooth side and a slightly fuzzy side. It's best to cut the squares so that the fold is pointing up when the fuzzy side of the fabric is up; that will ultimately put the smoother side of the fabric towards your face so the mask will seal better.

Once you've got the square cut, you need to mark a few points to guide the folds. The video walks through this process, but I've also drawn imperial and metric diagrams that shows the layout of the marks; scalable PDFs of both are available at my website,

If you're making a lot of masks, taking a few minutes to print out the diagram and make a template will save a lot of time.


If you look at a manufactured N95 mask, you'll likely find a pliable strip of metal along the top that helps the mask conform to the hollow on either side of your nose. A 2 1/2" long piece of wire under a 3" long by 1/2" wide piece of duct tape will accomplish the same thing.

Nineteen gauge annealed steel wire works well for this; it's light and flexible, but it also has enough of a memory to hold its shape -- but a paperclip will work, in a pinch. Stick the wire onto the tape, and the tape onto the mask, aligned to marks E1 and E2. Hold it back from the edge of the fabric about 1/8" so that the tape doesn't irritate your nose.


The next few steps are much more easily grasped if you watch the video, starting at about the 7:40 mark.

In addition to the pleat that was originally folded into the fabric, there are two additional folds that you need to make before shaping the mask: one from mark B1 to D1 and one from mark B2 to D2.

The mask is shaped by using the folds we've made to put the three marks on the side of the mask (A1, B1 and C1) on top of one another. When you're done, B1 should be on top of A1, and both of those should be on top of C1. Again, this is much easier to understand if you watch the video.

Adjust the folds a bit so the material makes a nice, symmetrical vee shape. You need to staple that vee in place, but make sure you've got the stapler far enough in to get through all five layers of material. You want to staple from the inside of the mask, so the points of the staple don't end up next to your skin, right in the center of the vee.

Now, turn the fabric around and do the exact same thing on the other side. Bring A2 down to C2, then B2 down to C2, make the vee symmetrical, and put in a staple.

Adjust the pleats so they align with points D1 and D2, then flip the mask over and smooth everything out. It might take a bit of fussing with the folds to get everything tidy.


Now to attach the rubber bands.

These rubber bands measure about 7" across, which is actually a bit big, but I wouldn't go less than 6". Thin rubber bands are better than thick ones. To attach them, just fold these little triangular tabs over the rubber band and staple each one down.


The mask goes on with the loops over your ears. The size can be adjusted by putting knots in the rubber bands. I have a gigantic noggin, and the mask fits me well with knots about 1/4" from the end of the loop.

Once you have the mask on, bend the wire over the nose until it fits comfortably, with no gaps.

I've got some tips for safely using the MOO MASK at my website,


There are a few steps to making these, but once you get going, you'll find that one person can make about a dozen in an hour. I'd encourage everyone to try, since the masks are likely more effective, and quicker to make, than other homemade versions.

I suspect some people will want to make these for themselves, but I would hope that anyone who makes one for themselves makes a whole pile of them for healthcare workers and first responders: the more they have, the less we need.

Please spread this video around: email it out, post it to your social media, tell people you know. I'd love to see hundreds or even thousands of these made so that we can help keep the infection rate down and all get back to normal life.

Thanks, everybody. Stay healthy, and be kind to one another.