Month: November 2020

New Limited Quantity Mask Fabrics for December

December is just hours around the corner and we thought it would be fun to add a few holiday season fabrics to our mask collection. The following four fabrics are available in *very* limited quantities. When they’re gone, they’re gone. Here they are:

We’ve also added a larger quantity (but still limited) of the following blue cotton with a scroll and check pattern.

Blue Cotton with Scroll & Check Pattern

Happy Holidays!

How to add a filter pocket to your two-layer masks

An imperfect but fairly easy method (no sewing machine required)

By Kitty

As promised, here’s a relatively simple way to add filter pockets to your two-layer masks!

Some caveats before you begin

If you ordered or were given a mask from Felix & Kitty before November 2020, it was most likely a two-layer one, since that’s what was officially recommended back then.  If your mask if from the time after we updated our mask construction (to have either filter pockets or three layers), you don’t need this tutorial.

FYI, if you think it’s a good idea to add a filter pocket to a mask that already has three or more layers, you might want to reconsider.  Masks with more layers aren’t necessarily any safer, and depending on what you use and how thick the final product ends up being, may be considerably LESS safe.  

NOTE: If you want more info on which materials benefit from multiple layers and which you shouldn’t double up, find it here.

Will this tutorial work for all mask styles?

Yes and no.  You can use the same principles for any style of mask, but that doesn’t mean it’s always a good idea.

In general, the basics of this tutorial will work fine with any mask with some 3D contouring that does NOT contain any pleats.  These are two examples (an Anteater mask and a “Put on a good face” mask, in this instance) of the type.

I wouldn’t add a filter pocket to a totally flat mask (like those plain rectangles with ear loops), because this style already tends to have major gaps around the edges due to the fact that they don’t make any provisions for the mountains and valleys of your face. 

The added stiffness of the filter pocket will probably make the gaps even worse.  Also, since flat masks just sit, well, FLAT, a filter would end up plastered against your nose and mouth, which could be really unpleasant, depending on the material.

I also wouldn’t add a filter pocket to a pleated mask, mainly because a flat filter sitting on the inside of the pleats would 1) render them kind of pointless and 2) shift around too much.  

The whole point of pleats is to open and close to accommodate facial movement as you talk and move your mouth.  A filter would just sit on the pleats and restrict them from their fold/unfold motion, and even get pulled out of place when it gets caught up in that motion.

In fact, following a good deal of experimentation (the reason why this tutorial is much later than I originally intended), I believe filters just don’t play nicely with pleats.  More on this in an upcoming blog.  In the meantime, if you love pleated styles, maybe stick with three layers instead of filter pockets.

Materials you’ll need

If you have a sewing machine and are comfortable using one, great.  Otherwise, a needle and thread will work fine.  Or if you’re not into hand sewing, a reliable glue gun that uses non-toxic, washable glue that bonds fabrics will do as well.

You will need some kind of fabric or other material which will withstand repeated cleaning.  If you machine-wash and heat-dry your masks, make sure your filter pocket material will stand up to the same treatment. 

Unless you have a machine for finishing fabric raw edges, or really love hand-finishing them with a needle and thread (in which case you’re a bit peculiar), stick to materials that will not fray.  Felt, heavy knits without too much stretch, and non-woven fabrics are all options.  

Other than that, you’ll want a pen or pencil, some paper, and a pair of scissors.  A few pins and a ruler are helpful but not essential.  If you don’t have pins, you may want a few clothespins or paper clips, or even bobby pins.

The prep

If I were you, I’d pre-wash and dry whatever fabric you’re using, even if it’s not supposed to shrink.  You don’t want your filter pockets doing something unexpected in the laundry after you’ve gone to all that trouble adding them.  If they do shrink, they can distort the mask and cause gaps around its edges, which is a big safety no-no.  You have been warned.

Step 1: The pattern

NOTE: You can skip this step if you’re only doing one or two masks, and just trace directly onto your fabric.  But if you have more than a couple to do, it’s much easier to make a paper pattern first.

To make the pattern, lay your mask on a piece of paper.  Flatten out one of the side edges of the mask (where the straps or elastics are attached) against the paper, and keep flattening toward the interior of the mask as far as you can go before the shape gets too 3-dimensional to stay down.  Trace around the flattened portion only.

Tracing from your Mask

Once you’re done tracing, remove the mask, and draw a line (use a ruler of you have one handy) connecting the ends of your traced lines.  This connecting line is shown in blue in the photo below.

Connecting the Traced Lines

Cut out the shape with your scissors.

Pin (or just hold, if you don’t have pins) the cut-out paper pattern against the inside of your mask to double-check that it’s the right shape and size.  Trim the paper down if needed.

The Cut Out Pattern

If there’s any chance you might confuse which way points up (if it even matters; it won’t for masks whose shape is symmetrical up and down), draw an arrow on the pattern to remind yourself.

Pattern Pinned to Mask

Step 2: Cutting out your pattern pieces in fabric

Pin your paper pattern to your chosen fabric.  If you don’t have pins, you can just trace around the paper with a Sharpie or chalk.

Pattern Pinned to Fabric

Cut out the shape.  If you traced the outline with a sharpie, try to cut off all the Sharpie ink, or the piece may end up too big.

First Piece Ready for Cutting

Now, FLIP OVER your pattern piece and pin (or trace).  Cut out the other filter pocket.  If you don’t do the flip, you’ll end up with two lefts (or two rights).  Of course, if your fabric doesn’t have a wrong or right side, this may not matter at all.

Ready to Cut the Second Piece

Now you have two mirror-imaged pieces of fabric!

Step 3: Attaching the filter pocket to the mask

If you’re going to be sewing, pin one of the fabric filter pocket pieces to the INSIDE of your mask, right side up (wrong side of pocket fabric facing the mask lining).  If you don’t have pins, you could just hold it with your hand, if you’re fairly confident with your hand-sewing skills.  Or you can use paper clips, small clothespins, or bobby pins to hold the pocket onto the mask while you sew.

First Pocket Piece Pinned to Mask

Thread a needle.  I used a contrasting colour thread so you can see it more clearly, but you’ll probably want to use matching thread, if you have any.  I also used a HUGE needle, much larger than you want, again so it shows up better in the photos.  Seriously, use a normal-sized needle; the big one was a pain to shove through the fabric layers.

Needle and Contrasting Thread

Remember, you are only sewing on the pocket where it touches the EDGES of the mask, not the bit that opens into the interior.  This is the pocket opening, so don’t sew it closed.  The next photo shows the most logical place to start the sewing.

Too-Large Needle for Illustrating the First Stitch

I’m not going to attempt to teach you hand sewing stitches here; there are loads of tutorials out there if you have no idea where to begin.  I’m using a simple overcast stitch, which isn’t any better or worse than many other possible stitches.

A Few Stitches In

As you can see, my stitches are neither even nor perfect.  I don’t much like hand-stitching, and I wanted to get this tutorial out quickly more than I wanted to make perfectly spaced beautiful stitches.  Remind yourself that it doesn’t have to look pretty to do the job, and don’t stress too much about your stitch quality, as long as everything stays on securely.  Just keep sewing around the edge.

When you reach the end, tie off your thread securely so your sewing doesn’t come undone, or back-stitch several times.  Remember not to stitch the opening of the filter pocket closed.  Huzzah!  You’re done.  With one side, anyway.

Now you do the same on the other side.  I sewed mine on by machine for comparison.

IF YOU ARE USING GLUE: Run a thin line of glue on the WRONG side of your filter pocket pieces, around the edges which will be attached to the mask.  Don’t put glue on the edge that will become the pocket opening! Following manufacturer’s directions for your glue, adhere the pocket to the inside edge of the mask.

Using the filter pocket

I tested out my new filter pockets using a coffee filter, but you can use any filter material you prefer, so long as it’s safe and reasonably breathable. If you’re not sure which one is for you, you might want to review the pros and cons of some options here.  

Mask and Coffee Filter

With CLEAN hands, fold the filter to make it fit, if needed.  Tuck the edges securely into the pockets on both sides to make sure they’ll stay put.  

Push the middle of the filter into the bowl of the mask to keep it somewhat clear of your face.  Now the mask and filter are ready to use.

All Done

Remove the filter after each use, and discard.  If it gets damp, you should replace it immediately, as soon as you can get your hands clean.  ALWAYS launder the mask before re-using!

So is this method of attaching filter pockets ideal?

Well, no.  Of course not.  

This tutorial lets you salvage those two-layer masks you acquired before the guidelines got changed on us, so you can get a bit more use out of them.  It isn’t meant to replace masks with purpose-built filter pockets, and definitely won’t do a perfect job — any filter you use with this method WILL touch your skin directly, and you could have a hard time keeping it clear of your nose and mouth.    

When I make masks with filter pockets from scratch, the pocket is designed to be a structural part of the mask, and covers the masks’s whole interior surface (the bits that go over your airways, anyway).  The filter then goes between the outer layer of the mask and the filter pocket/lining layer, meaning the filter itself never directly touches you.  This could be important; for example, some filter materials can be too abrasive when placed against sensitive facial skin.

This also means any filter will sit much more securely within the pockets with no danger of slipping out.  Since the filter pocket is made to follow any 3D shaping the mask itself has, the filter is kept lifted off your face, so you don’t accidentally get a noseful of filter if you breathe in too suddenly.

All the same, if you follow this tutorial method, you end up with masks that are compliant with the official recommendations, provided you use the right filters with it.  While I didn’t love the feel of the filters against my skin when I tested this out, it was perfectly serviceable, and still far more comfy than those one-size-fits-none disposable masks.

What to do with two-layer masks (if you can’t be arsed to do all this sewing)

I ended up donating my entire stock of two-layer masks (which I already had made when the guidelines changed) to a homeless shelter after adding filter pockets, which is a sight better than wasting them.  

If you have a sewing machine (or just a needle and lots of free time on your hands), but would prefer to switch to purpose-built masks with filter pockets and/or three-layer masks, you could do the same.

Or just sanitize and donate them as-is.  Seriously, ANY mask is better than no mask at all, and your local shelter will be glad to have them, filter pocket or no.  They also have the option of using two masks at once, one over the other, to get more layers (you could do this too, if the masks materials are breathable enough and the double elastic doesn’t bother your ears).  You never know — you could save someone’s life.

Next time on Aunty Kitty’s Mask Adventures

I’ll be trying to come up with a mask style with LOTS of extra breathing space to compensate for that third layer.  And no pleats, so it’s filter pocket-friendly for those of us who want one.  But it’s somehow still got to accommodate longer chins or large beards, sans pleats.  A challenge indeed.  

Also, hopefully, it will be simple enough in design and construction so it’s relatively affordable.  We’ll need that, since it’s been officially made very clear that we should all have several masks in rotation at any given time (because we really are supposed to change them whenever they get damp or soiled).  

Winter is here, Kittens.  That means your mask will get soggy from condensed exhaled breath when you go outside, so make sure you have two or three extra masks (sealed in a clean zippy bag) stowed in your purse/knapsack/bum bag/cleavage at all times.

Until next time, happy crafting!

The Big Mask Update – Part 3

An exhaustive (and exhausting) list of mask filter options, with pros and cons

By Kitty

In part 1 and part 2 of this series, I talked about the new recommendations regarding mask construction and procedures, the disposable mask issue, and the pros and cons of 3-layered masks vs. 2-layered masks with filter pockets.

This time, let’s talk mask filters.  Specifically, what your options are, their availability and safety, and why you might or might not want to use them.  Of course, this isn’t a complete list, because if you can name a material, someone’s probably gone and tried it, however bonkers.  These are just the things I’ve seen making the internet rounds.

DISCLAIMER: As always, nothing in this article is meant to be official medical or safety advice.  Everything presented here is either publicly available information that’s considered accurate at the time of writing, or just my opinion.  If you have health-related questions regarding the pandemic (or anything else), you should seek answers from your health care professional, not a sewing lady off the internet. 

The boring science-y bit (skip at your own risk)

Sorry, I know this is kind of dull, but it still has to be said.  Getting proper, reliable data from studies take time and funding and replication, and this pandemic is still pretty new in the grand scheme. 

The good news is that lot of studies regarding mask materials and safety seem to be in the works, but I wasn’t able to find many that have been published and reviewed, never mind reproduced.  This means there’s a lot of conflicting information out there, and what there is suffers from fuzzy definitions.

In the interest of not making this blog the length of a bible, I won’t be dwelling on the technical details of the studies I did find.  OR going into detail on a laboratory’s set-up of the equipment.  Or digressing into why sometimes it’s harder to capture larger particles than the smaller ones. OR complaining (much) about the non-standardized terminology some sources use when they publicize their findings. 

However, both the scientist and seamstress parts of me are somewhat outraged when I see test items like  “kitchen towel” or “cotton T-shirt.”  How thick a towel, what weave density, and what fibre content?  How thick a T-shirt, what kind of knit, and how tightly stretched was it, which hugely affects the space between thread loops in knit materials?

The point is that no one REALLY knows how well any of these materials work in real-life face masks right now, and even when there’s data being quoted, it might not mean what it sounds like.  One T-shirt could block only 10% of tested particles, but a heavier one might block 80% but only if you stretch it no further than 12%, and so on.  Test results for the same listed item (like “cotton T-shirt”) can vary wildly from study to study and source to source, partly due to that aforementioned lack of standardization.  Basically, trust no one, and use your own best judgment.

Filter material safety

I’ll mention safety information provided by manufacturers or retailers when I have it, but it should all be taken with a giant pinch of salt.  Different sources sometimes have conflicting opinions on an item — even on the exact same brand of an item.  Read material safety info and/or data sheets yourself whenever you can find them, but remember they don’t tell the whole story either.

For your reference

A naked SARS-CoV-2 virus (not encased in a droplet of fluid) runs about 0.05 to 0.15 microns, depending on who you ask.  Wearing the droplet, it’s 3-20 microns, give or take. 

Whether it can get airborne without its protective droplet coat and survive for any length of time is currently a question mark.  When we know this for sure, we’ll be much better equipped to decide what works and what doesn’t.

List of Potential Filter Materials. 

With that out of the way, here comes the actual list of potential materials.

Non-woven polypropylene or “PP” fabric (the kind used in some reusable shopping bags)

PROS: This is what the official Canadian recommendations say is the preferred choice for a third layer.  Available, if only by chopping up shopping bags (check to make sure it’s the right kind, though).  Washable and reusable.  Good breathability, good enough so you can use multiple layers to boost effectiveness if you’re so inclined.  Higher-quality PP fabrics are pretty durable, though not like, say, high-thread-count cotton is.

CONS: PP fabric can develop thin spots or otherwise lose structural integrity in ways that aren’t obvious unless you look closely.  Meaning you really have to keep checking.  Some, though not all, shed little flecks and bits as they get more worn.  One test found PP grocery bags only captured 11% of particles 0.3 microns and under, which is worse than bedsheets, kitchen towels, and coffee filters, among others — remember, that’s just in *this* study (others could say something totally different).  

Cotton T-shirt material

PROS: Cheap, easily available, and easy to DIY into reusable, washable filters.  Knit materials don’t fray, so you don’t need to finish the edges of your self-cut T-shirt filters.  Very breathable.  Mostly safe to have on your face.  Using a double layer boosts effectiveness, and is doable for some, since it is so breathable.  According to the Cambridge study (if you’ve been looking up mask material studies, you’ll have seen this one by now), one of the best for capturing droplets.  However….

CONS: One of the *worst* materials for catching particles 0.3 micron and under (only about 3%) according to a more recent test, though this one apparently used a much thinner and more lightweight material than the Cambridge study (remember what I was saying about standardization?  The specifics really do matter).  Pieces cut from T-shirt knits tend to curl up when laundered, so can be a real hassle to insert into filter pockets.

Those blue shop towels

PROS: Fairly easy to find in home improvement stores.  Easy to cut up into your own disposable filters.  Okay breathability, but not great.  Some tests say blue shop towels, especially those made from polyester hydro-knit or polypropylene, are quite effective at filtering droplets, though possibly less so than regular paper towels or cotton sheets.

CONS: Not reusable.  Some safety data sheets say they contain toxic chemicals and/or carcinogenic particulates (if you inhale them, that is, not when you wipe your hands), while others don’t.  This is a case where different sources don’t agree on the same product.  One source says the tested brand filtered under 20% of 0.3 micron and smaller particles, which isn’t stellar.

Common-o’-garden kitchen paper towels

PROS: Surprisingly good at filtering larger virus-sized and droplet-sized particles, according to at least one source.  Inexpensive, easily available, and easy to make DIY filters.  Quite breathable.

CONS: Not reusable.   Not as good at filtering Coronavirus-sized particles as droplet-sized ones.  One source said paper towels filtered 33% of 0.3 micron particles (which is actually better than lots of other materials, but not great).   So how well this works may depend on whether viruses can survive in the air without that droplet.  Doubling paper towel layers doesn’t help much with effectiveness.

Coffee filters

PROS: Cheap and easily available.  Said to be very effective by at least one test, though results may vary between brands.  Comes pre-cut into manageable sizes.  The American CDC recommends it as a disposable layer for improvised face coverings, though they say nothing about why.  Doesn’t cause moisture condensation.

CONS: Not reusable.  It might just be me, but I found coffee filters REALLY hard to breathe through, which is a huge problem for those who agree with me.

Felt, synthetic or wool

PROS: Easily available and cheap if you stick to synthetic craft felt.  Reusable and washable, though durability differs by type (wool is durable, synthetic less so).  It doesn’t fray when cut, so you don’t need to finish the raw edges.  Reasonably easy to breath through, though this will vary depending on thickness and density of fibres.  Wool felt wicks moisture VERY well, and prevents condensation.  Some sources say felt’s tangled structure makes an effective barrier for pathogens.

CONS: Can be expensive if you choose wool felt.  Synthetic felt can cause moisture condensation, and some kinds may not hold up through multiple washings.

Dryer sheets

PROS: Easily available and made from non-woven material.

CONS: Full of who-knows-what chemical additives, and usually fragrances, none of which were meant to be snuffled close up.  Breathability is hard to test through all that.  I wouldn’t do this one.

Interfacing, non-woven (woven interfacing is just general fabric, really)

PROS: Meets the “non-woven fabric” recommendation for one of your three layers.  Reusable and washable, at least somewhat.  Comes in lots of different thicknesses and finishes, so you can pick one you like.  Lightweight ones are fairly breathable, though possibly less of a barrier than the heavyweight ones.  Doesn’t fray, so you don’t need to finish the edges.  Easy to find in a fabric store or online.

CONS: Can get expensive, and heavier ones definitely don’t breathe well.  Not durable through multiple launderings.  Some types can develop irregular thin spots when washed.  If anyone’s specifically conducted a test on interfacing’s filtering ability, I haven’t been able to find it.


PROS: Easy enough to get, if you know what it is.  Washable and reusable.  Cozy for outdoor winter masks, since it’s often used to add warmth to sewn items. 

CONS: Nobody’s tested it that I know of, but since batting is actually designed to have lots of air space in it, I can’t imagine it would make a good barrier for anything.  Also, washing and drying sometimes creates irregular thin and thick spots.  Too warm to wear indoors, and not too breathable.

Dust and/or pollution filtration mask filters (usually rated PM2.5)

PROS: At least one study found these highly effective (97+%) at blocking tested particles, including air pollutants.  Since they’re already meant to go into a mask, they’re reasonably safe to wear on your face.  Supposedly quite breathable (I wasn’t able to get any, but it seems logical, for the same reason).

CONS: Supplies seem spotty right now.  Can be expensive.  Not reusable.  The study didn’t test for particles as small as a solo coronavirus when it’s not encased in a droplet, so we have no idea how these performs against airborne viruses (many air pollution mask filters are rated to block 2.5 microns, which is a LOT bigger than the virus that causes COVID-19, but smaller than the droplet in which the virus usually travels). 

HVAC system filters/home air filters

PROS: Fairly easy to find at home improvement stores.  One layer is more breathable than you might suppose.  Can be quite effective as a particle barrier, though how small a particle can get through depends on its rating (most will stop anything droplet-sized, though).  One test found HEPA filters stopped more than 80% of 0.3 micron-sized particles.

CONS: Not reusable.  Expensive.  Not tested for safety as a face mask material.  Even true HEPA-type filters aren’t usually rated to stop particles much smaller than 0.3 microns.  Most manufacturers explicitly recommend against using home air filters for face masks.  Some may contain components which are unsafe if inhaled.

Vacuum cleaner bags

PROS: Available, if somewhat spottily right now.  Some health professionals have recommended HEPA vacuum bags as an option for face masks.  Studies show they are very good at capturing even small droplets and large viruses (but not coronavirus-sized ones).

CONS: Not reusable.  Not tested for safety in face masks; some do contain materials that may be quite  dangerous if you inhale them. Most are very hard to breathe through, which creates problems all by itself.  Personally, I’d stay away from this one.

Wet wipes/baby wipes/pre-moistened towelettes

PROS: Er…They come in a carrying case?

CONS: They’re *wet*, people.  Wet = bad in masks, even if they’re wet with just water or something fairly harmless.  Some are soaked in an alcohol-heavy solution, which may be virus-unfriendly, but it’s also unfriendly to your airways.  Just don’t.  I wouldn’t even have mentioned this one, except it really is floating around out there.

Pads/sanitary napkins/panty liners and disposable diapers

PROS: Still widely available. 

CONS: Not at all breathable, even the thinnest types.  Many contain chemicals or gelling agents which are NOT intended for you to inhale.  Never even tested for effectiveness at filtering pathogens, as far as I can make out, but it surely doesn’t matter, as no one can breathe through these anyway.  Another option I was surprised to even see existed.

Bandanas, socks, handkerchiefs, scarves, towels, bra pads, underwear, nylons, etc (assorted items of clothing or household fabric goods)

PROS: Everyone has them lying around.  Usually washable.  Some (and only some) of them probably work as well as anything else.  In general, breathable material with a very close weave or tight knit pattern will do okay as barriers (you should NOT be able to see any spaces between threads or yarns when you hold it up to the light).

CONS: How effective any of these things may be depends ENTIRELY on its individual characteristics, so it’s all on you to decide.  Loose-woven or loose-knit materials make terrible filters.  The cut edges of some fabrics will need to be finished to prevent them from disintegrating when washed.  Incidentally, cotton bandanas were cited as some of the worst materials at blocking particles by some studies, though they didn’t say what weight or weave (cheap bandanas are normally made from thin, low-thread-count cotton). 

Gore-Tex (and other ePTFE fabrics)

PROS: Lets air and water vapour through, but not liquid droplets.  In principle, this makes ePTFE fabric both waterproof and condensation-proof (exhaled moisture should pass through instead of condensing on it).  I couldn’t find any studies regarding its effectiveness as a viral barrier, but it’s essentially a uniform film with micropores, so there are unlikely to be any thin spots or gaps.  Very durable in structure.

CONS: The manufacturer specifically states that this fabric doesn’t allow for enough airflow when used in a face mask, and that it doesn’t protect against airborne pathogens. Expensive.  Detergents can damage the waterproof qualities.  Air-permeable or not, I find it hard to actually get a lungful of air through Gore-Tex, which in itself makes it a bad option. 

Surgical sterilization wrap (Halyard and Medline are a couple of manufacturers)

PROS: Extremely effective at blocking particles (and just about everything else), which isn’t surprising, as this is what they use to keep instruments sterile for surgery in hospitals.  Technically, it can block more particles than N95 masks.  Definitely ticks the “non-woven polypropylene” box, in spades.   Comes in lots of different weights.   I don’t have access to any right now, and I can’t recall ever trying to snort air through it when I did, but I’m told it’s reasonably breathable. 

CONS: Hard to source, unless you have a line on surgical supplies, and expensive if you do find it.  Not reusable.  Not actually tested for safety or effectiveness in face masks, though at least a few medical professionals are trying out the material in masks for themselves, so we’ll see if anyone does a study.  The manufacturers say it’s not intended for masks, and they can’t support its use for the purpose.

The redundant option: Tightly-woven breathable fabric, like quilting cotton

Note: the reason I feel kind of silly mentioning this one is that if you’re going to use this as a filter, you might as well just make a three-layer mask and skip the filter pocket altogether.  But if you want to use high-quality cotton as a removable filter for reasons of your own, here are the pros and cons.

PROS: Super-breathable.  Most sources that tested this material found it to be at least moderate to good at capturing particles.  Easy to find, very durable, washable, and available in lots of colours, finishes, and weights.  Safe to wear against skin.  Moisture won’t condense on it.

CONS: Cut edges will fray, so you’ll need to finish them in some way.  Not a non-woven polypropylene-type thing, so not the first choice for official government recommendation for the third mask layer (they do mention cotton and linen as acceptable alternatives, though).

So what would Felix and Kitty use?

Your aged aunt Kitty doesn’t even carry a phone or a purse, because she’ll forget anything that isn’t sewn on.  In the same vein, I just know that I’d forget to pop a filter into my mask pocket every time I step outside for some kibble. 

For myself, I’m sticking with a mask made from high-thread-count, good-quality, breathable woven fabric.  Only now, I’ll use three layers instead of the previously recommended two.  Felix will most likely do the same, because he likes masks with pleats, which don’t play well with removable filters. 

I’ll most likely switch entirely to a style with lots of 3D space over my nose and mouth, like my Anteater or Ziggurat masks, because that extra layer means I will want all the extra breathing room I can get.  In fact, I’ve started to test out a few other styles with even more nose clearance, just in case we need them.

If I *had* to pick a filter for some reason, I’d try out the surgical wrap, if I could get it and assuming there was no danger of hospitals running short.  Of the more easily available options, I might try out wool felt and thick cotton T-shirts (they seem safer to me), and in a pinch, plain old kitchen paper towels. 

Why NOT polypropylene, like the official recommendation says?

This is just personal, but I don’t entirely trust a lot of non-woven materials.  Over many years of sewing, I’ve observed that many shed some dubious bits and bobs (aka fibres and particulates) when they get a bit shabby.  You see, dear Kittens, PP is basically a thermoplastic, and I feel like we swallow/breathe enough microscopic plastic particles every day without adding even more.

Also, some PP fabrics develop thin spots as they get worn, which are a hazard in masks.  If you have a reusable PP shopping bag that’s been through the wash a dozen times or more, try holding it up against the light.  Quite often, you’ll see semi-translucent patches.  Compare that with a solid cotton bedsheet you’ve washed and dried a hundred times, and you may start to see my point about durability differences.

In conclusion

This has gone on far longer than any blog should, so I’ll wrap it up.  Though I have much more to say on the subject of masks, filters, and updated safety data, which I’ll spout sooner or later.

I’ll put out that tutorial on retro-fitting filter pockets as soon as I can come up with a no-machine-sewing method that halfway works.  It’s turning out harder than I anticipated.

And hopefully, I can come up with a 3-layer/pocket-enabled, 3D mask style that 1) provides as much breathing space as my Ziggurat masks but 2) can accommodate a filter for those who want to use one and 3) is a bit simpler in structure, so it’s more affordable to buy and/or easier to produce for donation. 

Until next time, stay safe and warm, and try not to huff any thermoplastic crumbs….

The Big Mask Update – Part 2

A treatise on mask styles, filter pockets, and disposable masks

(Turns out there will be a Part 3.)

By Kitty

DISCLAIMER: As always, nothing in this article is meant to be official medical or safety advice.  Everything presented here is either publicly available information that’s considered accurate at the time of writing, or just my opinion.  If you have health-related questions regarding the pandemic (or anything else), you should seek answers from your health care professional, not a sewing lady off the internet. 

Last time, we went over a short summary of Canada’s latest recommendations regarding masks and filters, with an aside for some mask myths and potential mask materials.

This time, we’ll go into a bit more detail on how some of those materials handle when used in actual face masks, as well as the pros and cons of solid 3-layer masks versus masks with filter pockets.   Oh, and my thoughts regarding single-use face masks (spoilers: they’re not great, though possibly not for the reasons you’d think).

Some of my opinions are based on what little tested information that’s available at this date, and others on reasoning and my experience as a fabric worker.  If you want the science part, search and ye shall find, same as I did — though there’s precious little to find.  This isn’t the kind of article that’s going to list citations for all the studies I looked at, just a quick summary.

The government’s most-recommended 3-layer mask system

(And the problems thereof)

The official recommendation says to choose masks with at least three layers, preferably with a non-woven polypropylene-type material sandwiched between two tightly-woven fabrics.  Speaking as a seamstress, I find this problematic.  Not from an effectiveness standpoint, just a purely practical one. 

In my experience, every non-woven material like the one they’re talking about tends to deteriorate fairly rapidly, especially with repeated laundering and heat drying (remember, you’ll need to wash your mask after *every* wearing).

I don’t mean that they all curl up and die after one wash cycle — just that they will lose structural integrity much, much faster than, say, the kind of high-quality tight-woven cotton I might use for the outer shell fabric.  They become thin in spots and scrunched up in others, and that creates permeable patches, which kind of defeats the purpose.

Even more troubling: you won’t be able to *see* when the non-woven middle of your fabric sandwich has become useless if it’s hidden between two layers of sturdy quilting cotton! 

For myself, I’m sticking to three layers of high-quality, tightly-woven (or tight-knit) fabrics if I’m using a hidden permanent third layer.  I don’t fancy tossing out my perfectly good cotton masks every few wearings because I’m afraid the middle’s gone all worn and wonky.  Anyway, Big Gov says this is still a quite acceptable option.

They also say you could choose to have a mask with a filter pocket, and get that polypropylene third layer as a separate filter.  Which brings us to…

The masks with 3-layers vs. 2 layers with filter pockets

This is a complex issue.  But when you pare it down to essentials, it mainly comes down to personal preference, since at this point in time, we don’t have actual peer-reviewed science to tell us one is conclusively better than the other.

The complicated part: how well each system works depends on loads of factors, including but not limited to the fabrics used, how well it fits your face, what filters you choose (if any), how well filter/s play with the mask design, and what you find most comfortable and easy to use.

To VERY BROADLY generalize, assuming all other factors are equal (same quality of materials, same fit, etc), there are pros and cons to both.

3-layer masks

PROS: These are simpler to use, in the sense that you don’t need to insert and remove filters every time you wash them (which is after every wearing.  Right?  Right?).  You don’t need to worry about filters shifting around, or whether it’s covering all the relevant areas.  You don’t have to keep buying and replacing filters, keeping in mind that even reusable filter materials wear out much more quickly than any decent woven mask fabric.  Pretty much any design of mask can be made in three layers.

CONS: Some people find these harder to breathe through than two layers plus a filter, though that may depend on the filter material.  Edges and seams can get bulky where all three layers meet, especially if the mask pattern isn’t designed to minimize this.  The authorities say we should preferentially choose non-woven polypropylene-type material as the third layer, but it will wear out before the regular woven fabric, meaning you have to toss the whole mask.

Masks with a filter pocket

PROS:  Some people feel it’s safer to discard the filter piece after each use (though there’s no evidence that this is better than laundering a reusable material).  But you can now use a reusable polypropylene non-woven filter as the third layer and discard it when it starts to get worn, since you can actually see it.  You have the option of experimenting with different filter materials to see which one you like best.

CONS: Some people don’t want to faff about with filters every time they use their mask.  You have to keep buying and replacing filters, which always wear faster than good-quality shell fabrics.  Some filter materials are pretty dodgy (not breathable, ineffective, or even dangerous) so you really have to use your judgment.  Filters can shift in your mask, especially if the mask design isn’t compatible with it.  Which means some mask designs could be a no-no; for example, many pleated masks don’t play nicely with a lot of filters.  Less breathable filters can cause serious problems for people with respiratory issues.

What about single-use/disposable masks?

Officially, we’re asked to choose washable, reusable masks instead of single-use ones when possible for the environment.  Which is an excellent and valid reason all by itself.  I mean, we have enough problems with without making more of a hash of the planet.  The plague is no excuse to be ecologically irresponsible.

I have a whole other, seamstress/designer’s, perspective on the matter, which is that disposable masks are rather like “one size fits all” clothing.  They work fine if you just happen to be the tiny minority that they actually fit well.  For the rest of us — well, we all know that it should really be “one size fits none.”

Next time you see someone in one of those blue single-use masks, have a good look (from six feet away, of course).  Quite often you will see spaces on either side of their nose at the top of the mask, and gaps at the sides of the face where the mask doesn’t sit flush against the skin. 

If you have noticeable gaps between your face and the mask, it almost doesn’t matter what it’s made of, or how often you change it.  Anything that’s out there can just hop on in, and vice versa.  And the consequences of an ill-fitting mask could be far more serious than a bit of spillover from a one-size-fits-none stretchy bra.

Also, for what it’s worth, the government guidelines do specify that masks should fit well against the face without gaps.

Why don’t disposable masks fit better?

Most disposable masks are made as cheaply and therefore simply as possible.  They tend to be a pleated rectangle-type affair, sometimes with a nose wire which is supposed to make the ruler-straight top edge seal against the curve of our nose bridge. 

This most common single-use mask shape is a lot like our Accordion masks, which is the least popular design we have — for a good reason.  It’s one of the oldest mask designs, and for the longest time, at the beginning of the pandemic, it felt like the only available one, which is why I offered it originally. 

But your face isn’t a flat plane; it’s got peaks and valleys.  There’s only so much a rectangle can do to curve around all your in-and-out bits.  If you have a fairly narrow, small face without prominent cheekbones, eyes that aren’t deep-set, shortish chin and thinner or flatter mouth, this shape might work fine for you. 

However, the rest of us find that it makes for sizeable gaps when worn.  Also, the straight top edge can actually impede your vision if you wear the mask as high as you’re supposed to.  This is why you often see people wearing single-use masks dangerously low on their noses — just so they can still see downward.  Masks designed to scoop down under the eyes and up over the nose get around this problem, but aren’t commonly found in disposable form.

I’ve sewn countless masks for donation or sale since the early days, and NO ONE who has ever tried one of my newer designs (like the Ziggurat Mask, which is still basically a pleated mask, but with actual shaping for the nose, eyes, and chin) ever goes back to the flat rectangular pleated mask style.  I realize this is just anecdotal evidence, but I think it illustrates the point.

The OTHER disposable mask problem

We’re told that masks should be cleaned after every wearing.   In addition, if your mask gets wet, it ceases to be protective and you need to change it for a clean dry one as soon as you safely can.

With cold weather, your own exhalation condenses rapidly, meaning your mask WILL get damp if you’re outside for any length of time, say waiting for the bus or walking to the shops.  Which means you need to change it the moment you’re able to get your hands clean to do it.

It’s not a big deal if you keep several washable masks in rotation and always carry a couple of spares, as you definitely should, especially in the wintertime.  But imagine throwing out three or four disposable masks every day.  Do you believe that everyone who uses them will change them each and every time they get wet or soiled?

If you do, where can I get some of your faith in humanity? 

Even if you’re right, that’s an awful lot of masks in the landfill….

Next time, in Part 3:

This got way too long, so there will have to be a Part 3, in which your Ancient Aunt Kitty will go over many popularly suggested mask filter materials.  We’ll talk general safety, availability, pros and cons for everything from paper towels to vacuum bags to surgical sterile wrap, and maybe a few options you didn’t even know about.  If your ambition was to become a mask filter nerd, join me, and we shall…erm…rule the sewing room together. 

As for the add-a-filter-pocket-tutorial?

It’s in the works.  I’m trying out a few different methods to see which one/s will work best for people without my industrial machinery or specialty sewing notions.  Or even a sewing machine, because these days, not a lot of you have one.  I’m even trying a no-sew option, though I wouldn’t hold my breath for that one.

The Big Mask Update – Part 1

A sewist perspective on mask misinformation, 3-layer masks, filter pockets, new government recommendations, and other matters of safety

By Kitty

DISCLAIMER: As always, nothing in this article is meant to be official medical or safety advice.  Everything presented here is either publicly available information that’s considered accurate at the time of writing, or just my opinion.  If you have health-related questions regarding the pandemic (or anything else), you should seek answers from your health care professional, not a sewing lady off the internet.

NOTE: Most of the masks we’ve been making for sale and donation have been two-layered to date, because that’s what the official guidelines recommended at the time.  Obviously, we’re changing that.  In the meantime, you don’t need to toss out your old masks; I’ll be posting a tutorial shortly on how to retro-fit a makeshift filter pocket on them.


In the past week or two, the Canadian government has dropped some new official recommendations regarding face masks and COVID-19.  I’m not repeating all that info here, since you can get it straight from the source (and you should). 

But I thought I’d summarize some ideas that are most relevant to us regular folks, and also call your attention to some misinformation which has been making the rounds.  Some of the false claims are just silly, but others are downright hazardous, so it’s worth educating yourself.  So here’s an info-heavy, no-pictures, not-fun-but-relevant article that’s worth one read-through.

Despite what you may have heard, seen on shelves, or read on the internet…

1. Virus-Proof Masks?

No mask is virus-proof, self-sterilizing, prevents microbe growth, or any of those things that just don’t science.  I even saw one brand of mask that claimed that it used “sterilizing ultraviolet rays” to keep you from catching viruses (oh, I really hope we’re all too smart to fall for that). 

ABSOLUTELY NO MASK you buy (except N95 masks, sort of) can offer you a guarantee that it will prevent viral infection.  It’s actually kinda illegal to say it can.

2. Alternate Materials?

None of the following materials have been tested for effectiveness in face masks in real-life conditions.  This doesn’t mean they don’t work, just that they haven’t been put through proper robust scientific studies, so we just can’t know.  A material that works great in itself may be totally inappropriate for use in face masks.

Some of these may be proven effective in the future, and some are even currently recommended, in the absence of more data.  Others are just plain rubbish or even dangerous (I’ll go into a bit more detail on which, how and why on Part 2 of this series).

  • Paper towels, blue shop towels, facial tissues, newsprint, other paper products
  • Coffee filters, dryer sheets, microfibre tea towels, or other household materials
  • Baby wipes or sanitary napkins
  • HEPA filters, air purifier filters, air filtration system filters, vacuum cleaner bags (HEPA or otherwise)
  • Interfacing, craft batting, polypropylene non-woven fabric, felt, other craft fabrics
  • GORE-TEX fabric, tent material, and other rain-gear materials
  • Halyard H600 medical-grade sterilization wrap material, which I have high hopes will be proven to work at some point in the future.  But I’ve not been able to find any evidence at this moment that it’s any good for sewn face masks.

3. Reusable Filters?

A lot of available reusable filters are a bit questionable.  Most, if not all, of them have never been tested to see how they hold up over multiple washings, and some of them apparently totally disintegrate after being put through a hot wash-and-dry cycle or two.  So be careful and use your judgment if you’re relying on these.

4. Ventilator Buttons?

Masks with ventilator buttons/exhalation vents/breathing vents are basically useless.  Unless they’re plugged up with some kind of filter, in which case, what’s the point of having a vent in the first place?  Vent openings are not really different in principle from just punching holes in your mask.  This isn’t just my opinion, by the way; Canadian health authorities says much the same thing.

5. Best Material vs. Worst Fit?

It’s a myth that the most important thing about a mask is what it’s made of.  Even masks made from the very best medical-grade materials are worth squat if they don’t seal well against your face at the edges.  That makes sense; a virus or droplet doesn’t need to do the limbo through the tangle of mask fabric fibres if it can just shoot through the big gap at the sides or bottom of your mask!  Like water, electricity, and white-tailed deer, infectious particles often take the path of least resistance.

Actual government recommendations regarding masks, summarized

  • You should wear one anytime you’re in public, unless you have a valid medical reason not to
  • Your mask should consist of at least three layers of tight-woven, BREATHABLE fabric and/or have a pocket for a disposable filter
  • Masks should fit well, and stay close to the face at the edges, without any gaping
  • Your nose, mouth and chin should be covered by your mask
  • You need to change masks as soon as possible when they get wet or dirty
  • Mask materials should maintain their shape and structure after washing and drying (more on this oft-overlooked point later)
  • Choose reusable (not disposable) masks if possible

What NOT to do, simplified official Government of Canada version

  • Never uncover your nose or mouth, or hang your mask from your ear or off your chin (you know you’ve seen people doing this!  Don’t be one of them.)
  • Avoid masks with those “ventilation valves” (also called exhalation valves or ventilation buttons) or made from loose-weave materials or with holes
  • Don’t use materials that fall apart, like tissues
  • Don’t use non-breathable materials
  • Don’t put masks on anyone who can’t safely remove it themselves if it becomes necessary
  • Don’t put a mask on anyone who’d having trouble breathing
  • Don’t put masks on children under 2 years
  • Don’t choose masks that impair your vision or interfere with something you’re doing
  • Don’t share masks

Who SHOULDN’T wear masks?

  • Children under 2 years of age
  • Unsupervised children between age 2 and 5
  • People with health conditions that may be made worse by wearing masks
  • People who can’t easily remove masks if needed

What about face shields or those neck gaiter thingies?

Face shields don’t replace masks, though they do protect your eyes from flying droplets.  Because face shields don’t prevent droplets from entering or escaping through the open sides and bottom, they don’t protect you or others from spreading infection. You should only consider a face shield instead of a face mask if you’re unable to wear a mask for some reason.  You can wear both, of course.

Neck gaiters aren’t a good idea because they tend to slip around and need lots of adjusting (you shouldn’t touch any face covering while you’re wearing it, ideally), and because they’re hard to remove without contaminating yourself.  Again, you should consider them only if you can’t wear a face mask.

What should you look for in a reusable face mask (as per current new guidelines)?

1. It Fits *You*

It should fit YOU well.  Not your sister or boss or the model on the box.  This is probably the most-often-overlooked, yet perhaps the most important, factor in your hunt for the best face mask.  If there are visible gaps between the edges of the mask and your face, it doesn’t matter how great the mask material is, or how durable, or even how comfortable (yes, a mask can be comfy AND gappy at the same time).  It’s still an open door for infectious droplets to waltz in and out. 

So if you buy those one-shape-fits-all ten-pack masks, do the world (and yourself) a favour and check all around the edges in a mirror to make sure it’s conforming well to your face.  Do this after you’ve been wearing the mask for your daily activities for an hour or two, not right after you’ve put it on and adjusted it to perfection!

2. Minimum Materials

Masks should be made from at least 3 layers of breathable, washable, tight-woven (or non-woven, in some cases) fabrics that will hold up to repeated washing and drying (or at least 2 layers plus a pocket for holding disposable filters).  Since you should wash all masks after every wear, this is really important.  Also, any material that falls apart, frays, changes size, or loosens its weave after washing isn’t suitable for non-disposable masks.  Watch out for cheaply made masks with unfinished exposed seams, since fraying can lead to loss of protection.

3. Official Middle Layer Material

The official government suggestion is for the middle layer of the recommended three to be made from a non-woven polypropylene material (though they say another layer of tight-woven fabric is okay).  Buuuuuut….

4. The Professional Fabric Perspective

Here’s my professional fabric worker’s perspective on the above: most of those polypropylene non-woven fabrics tend to lose structural integrity much faster than, say, tight-woven cotton or linen.  If the middle layer is sandwiched between the two outer layers like the government suggests, how do you know if it’s disintegrating on you? 

Personally, I’d stick with another layer of tight-woven washable fabric for the middle layer. OR, if you want to use a reusable filter, opt for a filter pocket so you can see the non-woven polypropylene filter and change it when it starts to get manky.

5. Comfortable

It should be comfortable.  Every time you touch your mask while it’s on your face, you’re potentially introducing pathogens.  If you’re constantly adjusting your mask, you really need to try another fit, size, or style.  Not all styles work for all people, so it’s important to try different ones until you find one that works for you (you can always sterilize and donate the ones that didn’t work for you to your local shelter; someone in need will thank you).

Next Time, in Part 2:

Great-Aunty Kitty weighs in on assorted mask fabrics, filter materials, filter pockets, different mask design concepts for different faces and needs, and the who-why-how-when of each one.  And also, at some point before or after that, what you could do with all those two-layer masks you already have.