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Food Safety

We suspect that the very first human-made clay objects were cooking or eating vessels, or maybe water jugs. Nothing matches ceramic kitchenware for economy, durability, and flexibility of design and color. Here are a few guidelines for making, choosing and using ceramics in your kitchen.

For a ceramic piece to be "foodsafe," all surfaces that come into direct contact with food or drink must have smooth, unbroken glassy surfaces, without cracks, rough spots of texturing that water, juices or oils could penetrate. Such flaws can be havens for bacterial growth.
It is not uncommon, however, to see bands of unglazed clay on the outsides of handmade mugs, or unglazed rings at the bottom of plates and bowls. These bands do not compromise the ware's foodsafe status.
Do unglazed areas on your ware come in contact with food or drink? For pieces made from lowfire clays, any surface that comes in contact with food or drink must be covered with a foodsafe glaze that has been correctly fired in order to be considered foodsafe. Even when fired, lowfire clay remains porous enough that fluids may penetrate the surface and soak into the clay. Unglazed surfaces of pieces made from midrange (stoneware) and highfire clays may be considered foodsafe when fired to their full maturity because the clay particles vitrify enough -- they melt together enough -- to form a waterproof surface.
To be foodsafe according to US government standards, the glazed surface must consist of less than 3% metallic compounds (copper, cobalt, etc) which might leach into food or drink. This is especially important for mugs or cups that might be used for acidic liquids like orange juice or coffee. Some lead-bearing glazes can meet this standard when fired correctly, but that's difficult to verify when buying finished ware. It's simpler to avoid pieces glazed with lead-bearing products.
If you observe that any glaze on your piece changes color during or after contact with food or drink, do not eat or drink from the piece.
Raku glazes are never foodsafe, even if fired in electric kilns, because of their high metal content. Raku glazes are also rarely watertight.
Some pieces that meet the glaze standards may still not really be safe for use because of hollows, pits or holes in the clay itself, under the glaze. It's not uncommon to find small depressions inside moldcast mugs where the handle meets the body, or holes in the clay at the bottom of plates where the clay was poured into the mold. These holes may -- or may not -- have been filled and sealed by the glaze. You'll need to take extra care in cleaning these flawed pieces if you choose to buy them. We've heard some real horror stories about what people have eventually found in (or coming out of) these flaws.
Ceramic pieces with gold, platinum, or other "pure metal" decorations are almost never microwave-safe.
Some ceramic pieces are microwave-safe, and some are not. It depends on the amount and type of metals used in the clay and glaze, and the power of your microwave oven. The only way to be sure is to test each piece in the microwave. Fill it with water and zap it for 30 seconds at a time. Watch for sparks from the ceramic piece -- a clear indication there's too much iron! Handling the piece carefully, check for hot spots and to see how much the clay has heated up. If you find uneven hot spots, or the piece as a whole seems excessively hot compared to the water inside, it's not microwaveable.
Don't put cool ceramic pieces into hot ovens. Put the filled dish into the oven, turn the oven on, and allow about 10 minutes extra baking time compared to the recipe instructions. Allow the ceramic piece to heat up with the oven to minimize the risk of breakage.

At Georgies, we urge all you to test our products before use to determine their suitability for your purpose or your project. We also urge you to be conscientious in determining any risks associated with specific ceramic materials. We support your efforts by supplying in good faith information, derived from reliable sources, that we believe to be accurate. The safety information on these pages is a summary presentation, and not intended to be exhaustive in detail. If you have specific questions or concerns, we would be happy to supply further information on request.

Georgies Ceramic & Clay • 756 NE Lombard • Portland OR 97211 • 800.999.CLAY