History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c12.42

c12.42

The white body is free from any metallic colouring matter and forms the basis for the coloured varieties. Analysis shows that those having blue and green shades contain copper oxide, which was added to the paste probably in the form of a natural ore. This also served to produce a chocolate coloured ware when heated in a reducing atmosphere of the kiln, due to the formation of cuprous oxide. The light red variety containing ferric oxide was probably produced by the addition of red ochre to the raw paste Most of the glazed pottery specimens have faded by weathering to a light blue or green colour. The granular white body material has been found, however, to often contain black specks. These may be the carbonized remains of an adhesive that was found necessary to hold the ingredients of the paste together before it was dipped in, or painted with the glaze.