Work with ceramics can present a variety of hazards. The information presented below details those hazards and ways to mitigate the hazards to reduce risk.
Clays are minerals composed of hydrated aluminum silicates, often containing large amounts of crystalline silica. It also contains organic matter, sulfur compounds, grog (ground firebrick), sand, talc, vermiculite, perlite, and small amounts of minerals such as barium carbonate and metal oxides. Clays can be worked by hand or on the potter's wheel, or cast in a clay slurry into molds.
- Chronic inhalation of large amounts of free silica during clay mixing or weighing (sand, perlite, grog, and vermiculite may also contain free silica) cause silicosis. It may take years to develop the disease. Chronic inhalation of kaolin may result in kaolinosis.
- Inhalation of asbestos (may be found in talcs and vermiculite) may cause asbestosis, lung cancer, mesothelioma, stomach cancer, and intestinal cancer.
- Lifting heavy bags of clay and glaze materials may cause back injuries.
- Carpal tunnel syndrome may occur from throwing on a potter's wheel for long periods of time due to the awkward position of the wrists. Back and neck injuries may occur from bending over the potter's wheel for long periods of time.
- Clay scraps left, as well as pulverization and sanding-finished green ware, may produce an inhalation hazard due to the presence of free silica.
- Know the materials you plan to work with. Always review the SDSs for all chemicals used in a process so that you are fully aware of the hazards and how to mitigate those hazards, and use the least toxic and least hazardous materials possible.
- Use premixed clay whenever possible to prevent inhalation of dust during mixing.
- There should be separate rooms for clay storage and mixing.
- All clay mixers should be enclosed or used in a well-ventilated area.
- Appropriate machine guards should be in place on clay mixers to prevent adding clay or water while mixer blades are turning.
- Work clothes should be worn in the studio, and they should be laundered regularly and separately from other clothing.
- Always lift with knees bent to prevent back injuries.
- Carpal tunnel syndrome may be prevented by frequent work breaks and keeping wrists in a relaxed, un-flexed position as much as possible.
- It is recommended to cut still-wet clay into small pieces, air-dry, and soak in water to recondition clay.
- Do not sand pieces containing fibrous talc. Using water mist while carving or sanding. Use local exhaust ventilation as much as possible.
- Wet mop floors and work surfaces daily or on a regular basis to minimize dust generated.
- Only mix clay in well-ventilated areas. Local exhaust ventilation may be necessary. If local exhaust ventilation is unavailable and you think you may need respirator protection, please contact EH&S (firstname.lastname@example.org) for evaluation of your process and assistance with selection and fit-testing of appropriate respiratory protection.
Glazes used to color or finish clay pieces are a mixture of silica, fluxes and colorants. Glaze components are weighed, sorted and mixed with water. These materials are often in fine powdered form, and result in high dust exposures. Glazes can be dipped, brushed, poured, or sprayed on the ceramic piece. Groups of ceramic glazes include ash glaze, feldspathic glaze, lead glaze, salt-glaze, tin-glaze, etc.
- Lead poisoning (symptoms include damage to the peripheral nervous system, brain, kidney, or gastrointestinal system, as well as anemia, chromosomal damage, birth defects and miscarriages) may be caused by inhalation or ingestion of lead compounds. In addition, lead-glazed foodware may leach lead if not fired properly or the glaze composition is not correctly adjusted. Acidic drinks and foods such as tomato juice, citric juices, sodas, tea, or coffee, may increase the risk of leaching.
- Certain colorant compounds of particular metals are known or probable human carcinogens, including: arsenic, beryllium, cadmium, chromium (VI), nickel, and uranium. Antimony, barium, cobalt, lead, lithium, manganese, and vanadium colorant compounds may also cause inhalation hazards. Antimony, arsenic, chromium, vanadium, and nickel compounds may be hazardous from skin contact. Soda ash, potassium carbonate, alkaline feldspars, and fluorspar used in glazes are skin irritants.
- Potential inhalation of glaze mist may be caused by spray application.
- Dipping, pouring, and brushing certain glazes may cause skin irritation and bad personal hygiene habits may cause accidental ingestion.
- Use lead-free glazes whenever possible.
- If lead glazes have to be used, apply them only on non-foodware items. Lead-glazed pottery should be labeled as lead-containing. Raw cadmium or lead should not be kept in the studio.
- Whenever possible, avoid using colorants that are known human carcinogens and probable human carcinogens.
- Use local exhaust ventilation or respiratory protection when mixing and spraying glaze. Please contact EH&S (email@example.com) for assessment of your process and assistance with selection and fit-testing of appropriate respiratory protection.
- Wet glazes may not generate inhalation hazards. Good housekeeping may reduce the risk of inhalation or ingestion of hazardous materials. Wet mop spilled powders.
- Appropriate gloves should be worn while handling wet or dry glazes.
- Use local exhaust ventilations when applying solvent-containing glazes.
- No eating, drinking, or smoking in the studio, and wearing appropriate PPE such as gloves, and separate work clothes or coveralls. Always wash hands after work.
- Glaze waste, including paper towels or newsprint used to catch drips, should not go into regular trash or be poured into the sink. Follow instructions to dispose of these as hazardous waste.
Electric kilns and fuel-fired kilns are used to heat the pottery to the desired firing temperature. Electric kilns are the most common type.
- Inhalation of chlorine, fluorine, sulfur dioxide, nitrogen dioxide, and ozone is highly hazardous. Sulfur dioxide may be generated from bisque firings of high-sulfur clay. Inhalation of these gases may cause severe acute or chronic lung problems. Long-term inhalation effects include chronic bronchitis and emphysema. Fluorine gas may also result in bone and teeth problems.
- High temperatures may generate many metal fumes, especially lead as it vaporizes at a relatively low temperature, which are highly toxic by inhalation.
- Oxygen starvation and inhalation hazards may be caused by carbon monoxide from fuel-fired kilns or organic matter in clays combustions.
- Infrared radiation produced by hot kilns is hazardous to the eyes.
- Heat generated by the kiln can cause thermal burns and may also cause fires in the presence of combustible or flammable materials.
- American National Standards Institute (ANSI) approved infrared goggles or hand-held welding shields should be worn when looking into the operating kiln.
- Lead compounds should not be used at stoneware temperatures as the vaporization temperature is low.
- Combustible and flammable materials such as lumber, paper and solvents should be stored away from kiln areas.
- Always make sure the kilns are shut off even though it may have automatic shut off.