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2019 Jiggering-Casting Project
Beer Bottle Master Mold Project
Build a kiln monitoring device
Comparing the Melt Fluidity of 16 Frits
Cookie Cutting clay with 3D printed cutters
Evaluating a clay's suitability for use in pottery
G3948A Iron Red glaze: Can you help?
Make a mold for 4-gallon stackable calciners
Make Your Own Pyrometric Cones
Making a high quality ceramic tile
Making a jigger mold for producing cereal bowls
Making a Plaster Table
Making Bricks
Making our own kilns posts using a hand extruder
Making your own sieve shaker
Medalta Jug Master Mold Development
Mother Nature's Porcelain - Plainsman 3B
Nursery Plant Pot
Pie-Crust Mug-Making Method
Plainsman 3D, Mother Nature's Porcelain/Stoneware
Project to Document a Shimpo Jiggering Attachment
Roll, Cut, Pull, Attach Handle-making Method
Slurry Mixing and Dewatering Your Own Clay Body
Testing a New Load of EP Kaolin
Using milk as a glaze


A wide range of materials are used in ceramics. Many of them are harmless, they can be breathed or eaten with little effect. Hundreds of tons of clays are sold each year for the specific purpose of eating them! And many more for cosmetic and medicinal uses. Most ceramic materials are inert, insoluble and among the most stable of materials. That means that it is not dangerous to, once in a while, touch or handle the vast majority of materials. However, if there is constant exposure, then long-term effects need to be considered. Notwithstanding this, some materials do have specific acute or short-term exposure hazards (by ingestion or inhalation).

Material hazards are most commonly related to dust. But there is a need to be sensible about it. One cigarette, for example, does not kill. Nor do 100. But 100,000 can. Likewise, there may be some asbestos fibres in talc or vermiculite, but you will not be harmed by sweeping up a little of either. You will be harmed if exposed to the dust daily for years and take no precautions. Consider frits to illustrate the need for common sense: Hundreds are available. They are ground glass powders, which means each particle is a glass shard, potentially with razor-sharp angular edges! It is not easy to find hazard information on frits (likely because there are so many types and each pulverizes to a different particle shape). Yet simple logic tells us to be careful about breathing the dust. And, to illustrate the need for perspective, consider silicosis: It is a much more serious health issue than asbestosis. Yet pretty well all dust in nature contains some quartz. Even gardening, farming or just walking in dry areas exposes one to quartz dust. This is because quartz makes up 10% of the bulk of the whole planet. So minimizing exposure over the years is the common sense approach.

Some materials produce harmful fumes at certain temperatures during firing. Bodies or glazes with high percentages of manganese dioxide (and other metal oxide raw materials), for example, will fume and should be considered hazardous. Fumes don't settle the same as dust, they can stay in the air for long periods. The obvious precaution is to install a vent on your kiln.

Some materials are poisonous or toxic if eaten. Barium carbonate or lithium carbonate are examples. But this is not common.

There is a special need for caution about material hazards when production is being ramped up from a hobby level to a business. The economic and scheduling pressures often mean that precautions and facility hygiene are put aside temporarily (and never restored). It is thus important that safety and common sense be an integral part of any business plan to produce ceramics.

Related Information

Flow diagram of a pottery operation

Tap picture for full size and resolution

Each stage presents potential health hazards. Photo courtesy of American Conference of Governmental Industrial Hygienists.


Articles Crazing and Bacteria: Is There a Hazard?
A post to a discussion on the clayart group by Gavin Stairs regarding the food safety of crazed ware.
Articles Attack on Glass: Corrosion Attack Mechanisms
Max Richens outlines the various mechanisms by which acids and bases can dissolve glass and glazes. He provides some information on stabilizing glazes against attack.
Articles Is Your Fired Ware Safe?
Glazed ware can be a safety hazard to end users because it may leach metals into food and drink, it could harbor bacteria and it could flake of in knife-edged pieces.
World Health Organization information of carcinogenic hazards
Occupational Lung Diseases
PubChem, the world's largest collection of freely accessible chemical information
Patty's Industrial Hygiene, 4 Volume Set, 7th Edition
Permissible Exposure Limits to Substances – Annotated Tables from OSHA
WHMIS Safety Data Sheet Overview
Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
The Encyclopedia of Occupational Health & Safety
CDC Toxicity Profiles of many substances
International Labour Organization Chemical Safety Database
Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens
Glossary Leaching
Ceramic glazes can leach heavy metals into food and drink. This subject is not complex, there are many things anyone can do to deal with this issue
By Tony Hansen
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