underglaze

noun

Coloring or decoration applied to pottery before glazing.

In ceramics, having the properties that adapt it for painting on the body before the glaze is applied: said of a vitrifiable pigment: as, an underglaze color.

adjective

Applied under the glaze, that is, before the glaze is put on; fitted to be so applied; — said of colors in porcelain painting.

noun

A decorative slip applied to the surface of pottery before glazing.