A running list of terms used across ceramic.wiki articles. This page is what the inline dotted-underline glossary tooltips link out to for a fuller definition. Individual articles link to specific entries here by anchor (for example, crazing links its inline CTE tooltip to the entry below).
The fractional amount a material's length changes per degree of temperature change. Ceramic CTE values are small, typically expressed as a number times 10⁻⁶ per °C, but because fired ceramic is brittle, even a small mismatch between two bonded layers (like a glaze and its clay body) creates real stress. See crazing and shivering for what happens when that mismatch goes too far in either direction.
A structural change that cristobaliteA crystalline form of silica (SiO₂) that can form in a clay body during high firing, distinct from the quartz form silica usually starts as. (a high-temperature crystalline form of silica that can develop in a clay body during firing) undergoes at a specific temperature on cooling (roughly the 200–250°C range), where it snaps between two crystal structures with a sudden, disproportionate volume change. This is a related but distinct phenomenon from the quartz inversion that happens around 573°C, and both are a real source of cracking risk during cooling, separate from ordinary crazing.
A mixture of two or more materials whose combined melting point is lower than the melting point of any one of its ingredients on its own. Much of glaze chemistry amounts to combining materials to hit a eutectic (or near-eutectic) point at a target firing temperature.
The two common oxidation states of iron in ceramics. Ferric iron (Fe³⁺) is favored in an oxidation atmosphere and is associated with reds, oranges, and browns. Ferrous iron (Fe²⁺) is favored in a reduction atmosphere and is associated with greys, greens, and blues. See atmospheres.
A stage of drying between wet/plastic and bone-dry: the clay has firmed up enough to hold its shape and be handled without deforming, but still has enough moisture to be carved, trimmed, or joined to another piece. Named for the texture at this stage, similar to leather. Trimming a thrown piece's foot and joining handbuilt pieces together (see scoring and slip) both specifically require leather-hard clay, not wetter or drier.
The weight of a glaze or slip suspension relative to an equal volume of water, the standard way potters measure and adjust how thick a wet mixture is before applying it. See dipping for typical target values and how it's measured.