History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c15.s1.76

c15.s1.76

A small percentage of Arikamedu pottery was subjected to inverted firing, i.e., was placed upside down in the kiln with a fair quantity of carbonaceous matter stuffed inside. As a result of the firing the whole of the interior and a portion of the exterior (usually the rim) which came into direct contact with the fuel turned jet-black, and the remaining outer surface became red under oxidizing conditions and grey under reducing-conditions in the kiln. Briefly the former can be called black-and-red ware, and the latter, black-and-grey ware. Very picturesque effects were obtained if the pots were treated with a slip and salt-glazed in course of firing.