Antique Porcelain Jugs, Mugs and Ewers
The material for the body was by no means fixed and one design can be found in soft earthenware, stoneware and parian; in fact, it is occasionally difficult to decide between the last two, the body looking like a fine stoneware or a proto-parian body. Those illustrated on p. 146 [...]

ANTIQUE PORCELAIN: ENAMELS, GOLD AND PARIAN
ENAMELS
Enamels are used to obtain the colours on top of the glaze and are in simple terms finely ground coloured glass. This melts on firing and fixes itself to the glaze. Where it has started to flake off, the firing has failed to reach a high enough temperature to create [...]