Minerals and Metals in Ancient India v1.c11.s13.2

v1.c11.s13.2

Basically it has a hard, fine granular body, covered with a glaze. The prevailing coloured are bluish-green, although white, chocolate and red specimens have also been found. It has a compact granular structure, composed of angular quartz grains bounded together with a transparent cement. Its chemical analysis shows that here silica is the chief constituent which forms about 90 per cent of the total amount. It has been inferred that the original faience paste was composed of finely crushed quartz, or pure white sand, a glassy flux and a colouring matter. It is obvious that the moulded objects had to be dried and fired to bring about the fusion of the flux; but the question, how precisely the various ingredients of the paste were endowed with the necessary coherence and plasticity, is difficult to answer. It may be that some organic matter might have been in the course of firing long before the flux underwent fusion. Possibly silicate of soda was employed as a constituent of the paste and served to impart the desired property to the wet paste. This preparation of an alkaline silicate by the fusion of soda with sand, was well-known to the ancient nation who practised the art of glazing.