Handmade pottery care

The clay is rarely the problem

Stoneware fired to maturity is dense, non-porous and thermally robust. It handles a dishwasher, a microwave and usually an oven without complaint. What decides whether a specific piece can do those things is almost always the glaze — the glassy layer fused to the surface in the second firing.

That is why the answer to is this microwave safe is never a general one about pottery. It is a question about the individual piece.

The two rules that cover most cases

Metallic lustre must never go in a microwave. Gold, platinum, copper or any metallic detailing will arc — you will see sparks, and it will damage the piece and possibly the microwave. This is not a caution, it is a hard rule.

Crazed glazes should not go in a dishwasher. Crazing is a fine network of cracks in the glaze surface, sometimes an accident and sometimes a deliberate decorative effect. Those cracks hold water and staining compounds, and repeated dishwasher cycles drive both deeper. Over time a crazed piece darkens along the crack lines permanently.

How to tell if a glaze is crazed

Hold the piece under a light and look at the glazed surface at an angle. Crazing appears as a fine web of hairline cracks, like the surface of old porcelain. It is easier to see on pale glazes than dark ones.

The confirming test: run a fingernail lightly across the surface. A crazed glaze catches slightly. A sound glaze feels continuous. If a piece is deliberately crackle-glazed, the maker will usually say so and will usually tell you to hand wash it.

Thermal shock, which is the other real risk

Pottery cracks from sudden temperature change more readily than from heat itself. A stoneware dish taken from a refrigerator straight into a hot oven can crack, and so can a hot dish set down on a cold wet surface.

The practical rules: let refrigerated pottery come up to room temperature before it goes in a hot oven, start it in a cold oven where possible, and put a hot dish on a wooden board or a cloth rather than a stone counter. None of this applies to a mug of coffee — it applies to ovenware and to large temperature swings.

The quick reference

Decorative versus functional

A meaningful distinction that listings blur. Functional ware is made to be used and glazed with tested food-safe glazes. Decorative ware may use glazes that were never tested for food contact, and a decorative piece re-listed as a serving dish is a real category on marketplaces.

Any potter selling functional ware will state that the glaze is food-safe, because it is the claim that matters and they know it. Where a listing describes a piece as decorative and also suggests using it for food, treat that as decorative and use it for dry things only.

Chips, and what to do about them

A chip through the glaze exposes the clay body underneath, which on stoneware is dense but not glazed. On a rim, that is a comfort issue rather than a safety one. On the inside of a bowl used for wet food, the exposed body will absorb liquid slowly and can stain.

There is no home repair that restores a glaze — it would require re-firing. A chipped functional piece is best retired to dry use: a ring dish, a pen pot, somewhere it will keep being seen. The variation that made it worth buying does not go away because a rim chipped.