Studio safety

Masks and Respirators: Which One, and When

Wet clay is not the hazard. Dry dust is. Which means a mask matters enormously for about six activities and not at all for the rest of what you do here. This is which mask for which job, what the ratings actually mean, and why a mask that does not seal is theater.

Mask up whenever material is dry and moving: dry sanding bisque, handling raw powders, mixing glaze at home. Sweeping is a wet job, never a dry one. A fitted half-face respirator with P100 filters is the right tool. An N95 is the acceptable minimum for short jobs. A cloth mask does nothing.

When it matters, and when it does not What N95 and P100 actually mean Four videos, none of them ours
The six dusty jobs What to buy Three things people get wrong
A potter pulling on a half face respirator while a second potter points at its seal, with a disposable respirator and a blue surgical mask on a tray on the bench in front of them
Jump to a section
When it matters, and when it does not What the ratings mean The four kinds, and what each is for Fit, which decides everything What to buy Looking after it What people get wrong The whole idea, quickly Which mask to reach for Three things people get wrong Questions we get asked Keep going

Which mask, for which job, and why fit beats filter every time.

The whole idea

Wet is fine. Dry is the problem.

Clay and glaze both contain silica. In wet form it goes nowhere near your lungs. The hazard appears the moment material is dry and something makes it airborne.

So the question is never "am I doing pottery", it is "is anything dry moving right now". Throwing on the wheel with wet clay needs no mask at all. Sanding a bone dry pot indoors needs one badly.

The particles that matter are too small to see and they hang in the air for a long time after the job is finished. That is the part people underestimate.

Choosing

Which mask to reach for

Silica Respirators - What you need to know Ally Safety
  1. Throwing, trimming wet, hand building with wet clay. No mask needed. Nothing is airborne.
  2. Sweeping, or wiping a dry bench. Stop. Do it wet instead. That is the fix, not a mask.
  3. Dry sanding bisque, scraping dry clay, cleaning kiln shelves. N95 at minimum, P100 if you do it often.
  4. Mixing glaze, weighing raw powders, handling oxides. Half-face respirator with P100 filters. This is the job that earns the gear.
  5. Spraying glaze. P100, and outdoors or an extracted booth, and never in a shared room. We do not spray at The Clay Hole, so this one is for a home setup.
  6. Any of the above with a beard. A tight seal is not possible, and that goes for full-face masks too. Use a powered hood or helmet, or shave the seal area.

If you only ever buy one thing, buy a half-face respirator with P100 filters. It covers everything on this list.

Worth knowing

Three things people get wrong

A cloth mask counts for nothing

Cloth and surgical masks are not rated for particulates and do not seal. Against respirable silica they are decoration. This is not a small difference in performance; it is the difference between filtering and not.

Fit beats filter, every time

A P100 that leaks around the edge performs worse than an N95 that seals. Air takes the easy route. If you can feel a draft at your cheek or your glasses fog, the mask is not doing its job.

The mask does not fix the habit

Sweeping while wearing a respirator still puts dust in the air for everyone else and leaves it on every surface. Wet cleaning removes the hazard. A mask only protects the person wearing it.

The honest version

When it matters, and when it does not

Being precise about this matters in both directions. Overstating it makes people tune out. Understating it is worse.

Art Room Safety: Essential Tips for Preventing Clay Dust and Silicosis Art with Ms. Paula Liz Two and a half minutes on what silicosis is and how handling clay carefully keeps the dust down.
  1. Wet clay produces no respirable dust. Throwing, wet trimming, wedging reclaim, hand building with soft clay. A mask here does nothing except make you uncomfortable.
  2. Dry clay being disturbed does. Dry sanding of greenware or bisque (we sand wet at The Clay Hole), scraping dried slip off a bat, brushing a dry apron, chipping glaze off a shelf.
  3. Raw powders are the highest exposure in pottery. Weighing silica, feldspar, frits and colorants puts fine material straight into the air at face height. This is where a real respirator earns its money. It is a home job: we do not weigh or mix dry glaze materials at The Clay Hole.
  4. Sweeping is the classic mistake. A broom lifts settled dust back into the air far more effectively than the original job did. Wet mop or a HEPA vacuum, never a broom and never compressed air.
  5. The exposure that matters is cumulative. One dusty afternoon is not the risk. Years of small unprotected exposures is. Silicosis builds slowly and does not reverse.
  6. Context is worth keeping. A member throwing a couple of evenings a week in a wet-cleaned studio is in a very different position from someone mixing dry glaze for a living. The habits below cost almost nothing and remove most of what risk there is.

What the studio does about it

We buy premixed clay rather than mixing dry, which removes the single dustiest job in ceramics. Cleaning here is wet. If you see someone reaching for a broom, that is the moment to say something, and nobody will mind.

Reading the box

What the ratings actually mean

The letters and numbers are not marketing. They are a standard, and once you can read it the choice gets simple.

The number is the efficiency

95 means the filter captures at least 95 percent of particles at the hardest size to catch. 99 means 99 percent. 100 means 99.97 percent, which is the highest class recognized for this kind of respirator.

The letter is about oil

N is not oil resistant. R is somewhat. P is oil proof. For pottery there is no oil in the air, so N and P both work. Either way, the number is what matters.

N95: the acceptable minimum

Rated, disposable, cheap and widely available. Fine for short, occasional dusty jobs. It seals poorly against facial hair, it clogs, and it filters no vapors at all.

P100: the right answer for glaze work

99.97 percent, in a reusable cartridge on a rubber facepiece that seals far better than a disposable. The pink filters you have seen in the glaze room. This is what to wear when you are weighing raw materials.

FFP2 and FFP3

The European equivalents, if you are reading a guide from the UK or EU. FFP2 is roughly N95, FFP3 is roughly N99, a little under P100. Same idea, different label.

What none of them cover

Particulate filters stop dust. They do not stop gases or vapors. Solvent fumes need an organic vapor cartridge, which is a different filter entirely, and kiln fumes need ventilation rather than a mask, with one exception. Raku firing sends smoke and fumes out of open cans, so the raku certification tells you to bring a cartridge respirator with organic vapor cartridges if smoke worries you. A paper N95 only helps with the soot.

If it does not say N95, P100 or FFP on it

It is not a respirator. Cloth masks, bandanas, surgical masks and the paper "nuisance dust" masks with a single strap are not rated for respirable particles and do not seal to the face. They are not a lesser option here; they are not an option.

The hardware

The four kinds, and what each is for

  1. The nuisance dust mask. One strap, no rating, sold everywhere. It keeps visible grit off your face and does nothing for the particles that matter. Not suitable for any job on this page.
  2. The disposable N95. Two straps that go around the head rather than over the ears, a nose wire, a rating printed on it. The minimum for occasional dusty work. Replace it when it goes soft, gray or hard to breathe through.
  3. The half-face elastomeric respirator. A rubber facepiece with replaceable P100 cartridges. Seals properly, lasts years, costs about the same as a few boxes of disposables. The right tool for glaze mixing and the one we would point most people at.
  4. The full-face respirator. Everything the half-face does, plus eye protection and a far better seal. Worth it if you spray regularly or mix in volume, which are home jobs for us. It does not get around a beard, because its seal sits on the skin too. Heavier, hotter and more expensive.

The comfort point is the safety point

The best mask is the one you will actually put on. A respirator that is uncomfortable, hard to find or stored somewhere annoying ends up not being worn, and an unworn P100 filters nothing. Buy something that fits well and keep it where the dusty job happens.

Things to Know About Selecting and Using Reusable Respirators 3M Four and a half minutes from the manufacturer on choosing a half or full face reusable respirator and how its filter system works.
Buying The Right Masks And Respirators Training Hands Academy Thirteen minutes on dust masks versus respirators, the filter ratings, cartridges, fit and when to change filters. It comes from a woodworking channel, so the examples are workshop ones.
The part that decides everything

Fit, and how to check yours

Air is lazy. Given a gap at the edge of a mask and a filter to push through, it takes the gap. A perfect filter with a poor seal is close to no protection at all.

How Reusable Respirators Work and Common Mistakes to Avoid 3M Five minutes from the manufacturer on how a reusable respirator goes together and the common mistakes: fit, assembly, replacing filters, using a prefilter and keeping it clean.
  1. Get the size right. Half-face respirators come in small, medium and large, and most people have never been told that. A medium on a small face leaks along the jaw.
  2. The positive check. Cover the exhale valve with your palm and breathe out gently. The facepiece should bulge slightly and hold. If air escapes around the edge, reseat it.
  3. The negative check. Cover the filters, breathe in gently. The mask should pull in against your face and stay there. If it does not, the seal is broken.
  4. On a disposable, mold the nose wire properly with two hands, not a pinch, and put both straps around your head rather than looping them over your ears.
  5. Facial hair breaks the seal. Not a little: a NIOSH-approved respirator cannot seal against stubble. The options are a powered unit with a loose-fitting hood or helmet, or a clean seal area. A full-face mask does not help, because it seals on the skin too. There is no third answer.
  6. Glasses fogging is a signal. That is your breath escaping upward past the seal, which means unfiltered air is coming back in the same way.
Shopping

What to buy, without overthinking it

Bring your own. We do not sell respirators, and the whole kit costs less than a bag of clay and a bottle of glaze.

  1. One half-face respirator, in your size. The common 3M and Moldex half masks are inexpensive and available everywhere. Try the size if you can; if you cannot, medium fits most adults and small fits more people than expect it to.
  2. A pair of P100 particulate filters. The pink ones. They last a long time in studio use and are cheap to replace.
  3. A box of N95s as the backup. For the day you forgot the good one, or a visitor needs something, or the job is two minutes long.
  4. Skip the combination cartridges unless you need them. Organic vapor cartridges cost more and matter only if you are working with solvents, which on our pages means alcohol inks and the Pebeo paints, and those happen on the outside tables anyway. The other time to own them is raku, where the raku certification says to bring a cartridge respirator with organic vapor cartridges if smoke worries you.
  5. Consider a powered hood or helmet if you have a beard you are not willing to lose. A half mask will not seal over a beard.
  6. A cheap plastic box to keep it in. A respirator left on a shelf in a dusty room collects dust on the inside of the facepiece, which you then press against your face.
Keeping it working

Looking after it

  1. Wipe the facepiece after use, inside and out, with a damp cloth. Not the filters.
  2. Store it in a sealed box or bag, away from the dust it is meant to protect you from.
  3. Replace particulate filters when breathing gets harder. That resistance is the filter doing its job and running out of room. There is no fixed schedule; the feel is the guide.
  4. Replace the straps and gaskets when they wear out. Rubber goes hard and stops sealing long before the facepiece looks worn out.
  5. Throw out a disposable when it is soft, gray or damp. A loaded N95 is not filtering well and is uncomfortable enough that you will stop wearing it.
  6. Redo the seal check every time you put it on. It takes five seconds and it is the only thing that tells you the mask is working today.
Common mistakes

What people get wrong

Wearing it for the wrong jobs

A mask at the wheel while throwing wet clay, and none while sweeping up afterward. That is backwards, and it is the most common pattern we see.

Treating a mask as a substitute for cleaning wet

The mask protects one person. Wet cleaning protects the room and removes the dust permanently. If you can only do one, clean wet.

Never checking the seal

Most people put a respirator on once, decide it feels fine, and never test it again. Straps loosen, gaskets harden, and faces change. Five seconds, every time.

Keeping a disposable far too long

An N95 kept in a bag for a year, worn twenty times, soft and gray. It stopped working a long time ago. They are cheap for a reason.

Assuming a particulate filter stops fumes

It does not. Dust filters catch particles. Solvent vapors and kiln gases pass straight through. Kiln gases are handled by ventilation, and solvent vapors need an organic vapor cartridge, not a pink dust filter.

Buying the expensive one and leaving it at home

The gear only counts when it is on your face. Whatever you buy, keep it where the dusty work happens.

Questions we get asked

The ones that come up at the tables

Do I need a mask to throw on the wheel?

No. Wet clay does not produce airborne dust, and there is nothing for a mask to filter. Save it for the dry jobs, where it genuinely matters.

Is a cloth or surgical mask good enough?

No. Neither is rated for particulates and neither seals to the face. Respirable silica is small enough to go straight through and around them. If it does not say N95, P100 or FFP on it, treat it as no protection.

N95 or P100?

N95 is the acceptable minimum for short, occasional dusty jobs. P100 in a reusable half mask is the better answer for anything regular, especially mixing glaze, because it filters more and, more importantly, seals better. If you are buying one thing, buy the P100 setup.

I have a beard. What are my options?

A half mask cannot seal against facial hair, and no amount of tightening changes that. The real options are a powered air unit with a loose-fitting hood or helmet, or a clean seal area. A full-face respirator does not solve it either, because its seal sits on the skin the same way. The other honest option is to avoid the dustiest jobs and let someone else weigh the dry materials.

How do I know when to change the filters?

When breathing through them gets noticeably harder. Particulate filters do not expire on a schedule; they load up with what they have caught. In normal studio use a pair lasts a long time.

Should I be worried about silicosis?

It is worth taking seriously and it is not worth panicking about. It comes from years of repeated unprotected exposure, and it is far more common in industrial settings than in studios where the clay is bought premixed and the cleaning is done wet. The habits on this page remove most of the risk and cost almost nothing.

Does a mask help with kiln fumes?

No. Particulate filters stop dust, not gases. Kiln fumes are handled by ventilation, which is why kilns are vented and why you stay out of a room where something is burning off. A dust mask gives a false sense of safety there, with one exception. Raku firing sends smoke and fumes out of open cans, so the raku certification tells you to bring a cartridge respirator with organic vapor cartridges if smoke worries you. A paper N95 only helps with the soot.

Does the studio provide masks?

Bring your own. A respirator has to fit your face to work, so a shared one is the wrong idea anyway. The whole setup is inexpensive and it is yours.

One last thing

Cheap, boring, and it works

There is no interesting version of this topic. A respirator that fits, worn for the six jobs that need it, plus a wet mop instead of a broom. That is the entire answer, and it costs about the price of two bags of clay, once.

What makes it worth writing down is that the risk is invisible and slow. Nothing about a dusty afternoon feels like a problem, which is exactly why the habit has to be a habit rather than a reaction. Get the gear, keep it where the dusty job happens, and check the seal every time.

Wet clay needs no mask. Dry powder, sanding and sweeping do. A fitted half mask with P100 filters covers all of it, an N95 covers the short jobs, and cloth covers nothing.

If you want the ratings explained, the four kinds compared and what people get wrong, switch to the Comprehensive Version at the top of the page.