Engobe

Engobe is a clay-containing casting compound and a generic term for a low-viscosity clay mineral compound used for colouring or coating ceramic products. It can also be a slagger. However, engobes are also a mixture of slip and glaze or coating masses without slip. Unlike glazes, engobes do not normally form a protective layer for the ceramic product.

Engobes are applied to the ceramic before firing. The engobe forms a smooth surface with a matt-silky lustre and can seal the surface under certain circumstances - similar to a glaze - when it sinteres at a slightly lower temperature than the clay of the actual vessel. It also gives the clay a different colour and therefore also serves as a decorative element.

The "iron engobe", which originated in the Rhineland, is also known as "clay glaze". However, clay glaze is a special opaque engobing technique, whereby the glaze is made from slurried clay that melts at relatively low temperatures and, depending on the composition of the clay, takes on the colours brown (iron), dark brown to black (manganese) or yellow (lime) after firing. Clay is contaminated clay mixed with sand. Clay glazes are applied either to dried or biscuit-fired pieces.

The picture above shows the technique of engobing around 750 BC in China. Zodiac signs were refined with a clay glaze.