Clay glossary

The structure of unfired or fired pottery in which the materials are aggregated in the form of layers or strata.

A fine mesh sieve, usually made from phosphor bronze or stainless steel, and supported by a strong frame.

The solubility of lead glazes in particular in diluted hydrochloric acid.

Partially dried clay ware. The ideal stage for turning, fettling, sponging, etc.

This is a method of decoration involving manufactured transfers or ‘decals’. The printing of the transfer is done by printing the decoration in lithographic oil, the colour then being dusted onto the oiled areas. The completed transfer is applied to a clay surface that has been previously coated with a tacky size, rubbed down and the paper backing sponged off. This process has largely been replaced with slide off transfers.

The loss in weight of clay or any other material expressed as a percentage of its dry weight when it is heated under specified conditions.

L.S. or low sol glaze. Defined by the Pottery Health Regulations as a glaze which does not release more than 5% of its dry weight of soluble lead when subjected to a specified test using hydrochloric acid.

An iridescent optical appearance, due to light reflections producing diffraction patterns on a glazed surface. Produced by very thin coatings of metallic substances fired onto the glaze.