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How to Clean & Work
With Less Clay Dust 
cleaning      smoothing clay     reworking clay
mixing clay    studio design

This page is meant to give ideas for reducing clay dust because long term exposure to clay dust may lead to silicosis.  Silicosis can be a fatal lung ailment.  With good habits clay work can be a healthy lifelong career as it has been for many people of many cultures in the past.

bad ideas
Dusting, sweeping, and vacuuming are not recommended for clay because these methods put dust into the air.  Depending on the heating and air conditioning system, dust might be circulated to other areas as well. 

Some people place "walk off" rugs at the doorways to try to get the clay from tracking to other areas.  These rugs are impossible to clean in a safe way unless they can be rolled up and totally laundered in a large commercial facility.  Vacuuming simply pulls the dust to the surface where it is picked up and spread by traffic.  Some say the smaller silica particles that pass through a vacuum filter will stay airborne for 4 days.  I use a piece of outdoor carpeting at the door of my studio.  I hose it off on the driveway and wash it in a kids plastic swimming pool.

The particular clay you are using is not an issue.  All dry pottery clay makes silica dust when walked on.  Keep it wet to avoid dust. 

 

good ways to clean up
Daily wet mopping or hosing down to a floor drain is good.  An existing room can be modified in one area for potter's wheels by raising the floor 6 inches.  This way the floor can slant toward floor drains.  This part of the room is divided from the rest of the room by a cement block half wall.  Students can hose down the wheel area at the end of every work session.  Large wet sponges are essential to clean work tables, counters, wheels, and small floor areas.  Use repeated sponging with washed out sponges to remove clay haze.

Students can be instructed to use wet sponges to immediately spot clean any drips around the wheels and pick up all crumbs before they get walked on.  Train them to carry two clean sponges from the sink so the first sponge gets the mess and the second sponge removes the residue. This can significantly stretch the times between total cleaning.

Some potters have a shop vac outdoors with a small pipe through the wall for the vacuum hose.  They use a shop vac that can have water in it and it can pick up water.  By locating it outside, any dust that might be blown out of the vac is dissipated outside.  I would only use a vacuum if it is outdoors where the dust can dissipate. 

who is at risk?
Teachers are much more at risk than students because of the time spent in this environment.  However, students need to learn proper respect for the dust in case they  decide to continue working in clay over a period of years. 

If cleaning makes any dust at all, it should be done at the end of the work day so the dust settle out of the air before the space is inhabited.

never allow sandpaper
In the days before they knew about the hazards of clay dust, the workers who sanded the mold marks from greenware in pottery factories died within a few years from silicosis. Never work on dry clay. Smooth it by sponging. If it is too dry, spray it with water.  It can be wrapped in plastic, and sprayed again until wet enough.  Do this gradually, but repeatedly to avoid expansion cracks from the water.  With a bit of practice, it is possible to completely soften a piece with damp cloths inside the plastic wrapping. 

how to rework scrap clay without making dust
It is difficult to mix clay without making any dust.  Moist trimmings should be immediately placed in a plastic garbage can of water. 

Large chunks of clay that are too hard to use do not need to be broken before soaking.  Once clay is totally dry, any size piece will slake and turn to mush if you place it in clear water.  Do not stir it until it is all mush, or it may seal the surface and prevent the water from penetrating the clay cracks.  This does not work with large moist pieces because they are not porous enough.  Just allow them to dry before placing them in water.

Once the clay is mush, you can take extra water off the top.  I dip the water into another garbage can so the suspended clay is not lost, but just becomes part of the next batch. 

The thicker mush is then dried until it is ready to wedge.  There are various ways to dry it.  Place it several inches thick on any porous material.  I like canvas better than plaster because I hate it when small pieces of plaster get in the clay.  The pieces of plaster expand after firing.  This breaks the pots or causes pieces to pop out of the surface.  Canvas on the webbing of an aluminum lawn chair allows the clay to dry from the bottom as well as the top.  Porous bisque trays would also be safe for drawing out extra water.

When clay is nearly dry enough, make it into large arm size coils.  Make big arch forms from them and set them around the studio overnight to firm up.  When  the clay is ready, seal it in plastic until you are ready to use it.

mixing from dry clay without inhaling dust
There is probably no way to mix clay from dry clay and be absolutely dust free.  Either buy premixed moist clay or use good a good exhaust fan and a very good dust respirator.  By working very carefully, you can minimize the dust as you mix clay. 

Dust masks must be tight fitting on your face and have serious dust filters that are rated for very fine dust.  Look for the NIOSH rating when purchasing a dust mask.  I use masks with #TC-21C-166 and #TC-21C-231.

Exhaust fans must blow the dust outside and be powerful enough so that you can see the dust moving away from you.  There must be a source of clean air.  If you have to place your face in the dust, do not inhale until you are back in clean air. 

If you are using a power mixer it should be placed between you and the exhaust fan.  If the mixing or other dust making activity is done in the working studio, plan do it at the end of the workday so airborne dust settles before you inhabit the studio again.

Never dump dry clay into the mixer or into a mixing container.  Place dry clay all the way down in the container.  Do not drop it.  Put it gently and slowly into the mixer or container so no dust raises from the event.  Close the mixer before running it.  Be patient.  Retire to a clean area while the mixer runs.  When opening a mixer, back off, hold your breath, and wait in a clean air place while the air clears at the mixer.

Launder clay clothing often.  Remove clay shoes before entering house.
Do not wear clay cloths in the house.  Keep some environments totally clay free.

designing the ideal clay studio or classroom
  • Use a separate building, rather than in the house where you eat and sleep. 
  • Provide an outdoor area or a separate and properly ventilated room for clay mixing.
  • Provide an outdoor area or a separate and properly ventilated fireproof room for firing.
  • Make it easy to hose down the floor.  A smooth sealed surface is easier to clean.
  • For areas that cannot be hosed off, equip it with a vacuum cleaning unit that is located outside with inside pipes and hoses.

table covers for clay work in art classes

  • Clay slabs often stick to the surface on which they are formed. Therefore, rolling slabs between two canvases allows the canvas to be peeled off of the clay to release it.
  • Coils cannot be rolled on a smooth table without sticking.
  • Provide canvas table covers that can be sponged clean and rolled up or stacked away. Do not brush them or shake them indoors. Periodically clean them seriously by hosing outside on a sidewalk or parking lot. They can also be soaked in a plastic wading pool.
  • Some teachers use the back of gessoed painting canvas.
  • Dupont Tyvec made as house wrap is an alternative to canvas.
  • Shower curtain liner plastic may work as a table cover for some things.
  • Velcro fastening felt around the edge of the tables can be used to attach covers that have Velcro hook tab attached to the canvas back corners. Sticks along the edge of the canvas allow fastening canvas with c-clamps.

pounding and wedging surfaces

  • Do not allow clay pounding on loose canvas covers on tables in a classroom because dust will be liberated.
  • Pounding and wedging can be done on thick slabs of concrete or plaster
  • Plaster can be tightly covered with heavy canvas to prevent plaster chips from contaminating clay. Dampen the canvas slightly to prevent dust. Scrape clay off with plastic putty knife and sponge it clean when finished.

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Marvin Bartel, 2001. Last updated December, 2005. All rights reserved. Copying or publishing is prohibited without permission.
Disclaimer - This page is in progress and posted by Marvin Bartel - There may be other hazards not included here, so just because something is not listed here, does NOT mean that it is safe to eat, drink, touch, or inhale. If you know of a ceramic hazard not mentioned here, please contact me.
        Many materials have not undergone tests for every possible hazard, and illnesses are not always attributed to the correct causes. Therefore, treat all materials with respect. Use common sense. I take creative risks in artwork, but I try to avoid risk in my working methods. 
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Back to Goshen College Art Department Safety Page.
Updated 10-17-2001, Marvin Bartel