Ceramics

Clays and Glazes

The main environmental issues in this industry are energy conservation; air pollution from kilns; water pollution from grinding, molding, glazing and washing; and toxic chemical hazards from heavy metals in ceramics and in glazes. The industry ranges from home-based pottery producers to highly advanced materials engineering firms.

The production solution for chemical hazards and water pollution is substitution of non-toxic ingredients in mixes and glazes, in particular the avoidance of lead, cadmium and other heavy metals.

Wastewater generated from pottery and art studios may contain significant amounts of pollutants such as heavy metals and toxic organics. Many materials used in pottery studios contain significant amounts of heavy metals. The pigments added to glazes commonly contain mineral oxides of such metals as chromium, cobalt, copper, iron, manganese, nickel, and vanadium. Glazes are primarily composed of potassium, calcium, magnesium, and aluminum silicates. Clay is a hydrated aluminum silicate. Both clays and glazes have been shown to contain trace levels of heavy metals.

In pottery, outside vented kilns are important, as is a careful choice of materials -- most potters know to avoid lead glazes and lead frits, but many don't know that flint, feldspars, fluorspar, and some compounds containing barium, lithium, manganese, or nickel can also be toxic. Children should avoid the pottery studio, as they are more highly susceptible to the toxics used in pottery than are adults.

Mixing Dry Clay

This can be highly hazardous because of the potential for inhalation of powdered or China clay which might contain asbestos, sand, perlite, grog, or vermiculite which can cause silicosis. Buy premixed clay, use local exhaust ventilation, a respirator and a wet mop for clean up.

Avoid or reduce the use of heavy metals in mixes and glazes

Glazes that do not contain lead or other heavy metals are commonly available. Metals in ceramic mixes are used for their engineering properties. Product engineers should research non-toxic ingredients and avoid probable carcinogens. Colorants that contain antimony, barium, cobalt, lead, lithium, manganese, or vanadium should be avoided.

Applying Glaze

Spraying hazard, solvent-based glazes hazard.
Spray in spray booth exhausted to outside & explosion proof; wear respirator; use exhaust fan; use good hygiene; wear gloves; wear special clothes; collect & combine scrap glazes to use again

Water re-circulation

Wastewater can be stored so the suspended particles settle to the bottom, then the water can be reused for cleaning. Sludge can be collected, dried and made into inexpensive bricks rather than disposing it.

Switch to propane or natural gas fuel

If available and competitively priced, these fuels have significantly less emissions and can increase production quality and speed.

New kiln design

Vertical shaft brick kilns allow increased production rates and significantly decreased emissions through improved combustion air-flow efficiency. Several other kiln designs have also proven to be relatively low-cost and much more efficient than traditional ovens or kilns. Chlorine, fluorine, sulfur dioxide, nitrogen dioxide, ozone highly toxic can be emitted during kiln firing. Lead and other metal fumes vaporize; carbon monoxide can be produced from kilns; ventilate kilns directly outside; keep kilns in separate room; wear infrared goggles or hand-held welding shields (1.7-3.0 shade).

Electric Kilns

Use ventilation; surround kiln with fireproof curtains; test commercial canopy hoods; use direct exhaust system for octagonal kilns; don't store combustible materials nearby; place kiln away from floor and wall; have 2 shutoffs.

Fuel-Fired Kilns

Put carbon monoxide alarm in area where indoor kilns are; gas lines should be installed by professionals, and have regulators; shut off gas and power if gas leak suspected; have bigger canopy hoods; make chimneys high enough

Links

These links below may be of further help:

The city of Palo Alto, CA provides some information and publications
Pottery and Art facilities source control program
Check out this chart of Health & Safety in the Arts
CleanProduction.com offers some tips for increasing efficiency and reducing waste

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