Effects of clay characteristics on fabrication and glazing behavior of ceramic products from Tissamaharama red clay

Abstract

In this research work, clay deposits located at Tissamaharama region vrcji investigated for mineralogical characteristics and to identify suitable fabrication and glazing techniques. The samples were collected from a site where clay mining is been already done for the pottery industry. X-ray diffraction (XRD) analysis and chemical analysis were used to determine the mineralogical characteristics of the clay samples. XRD analysis of the clay samples showed the presence of Quartz, phyrophyllite and montmorillonite. Chemical analysis indicated the presence ofCaO, Fe:(),, Si02 and AljOj. The Tissamaharama clay belongs to montmorillonite-kaolinite group with calcareous material and hence this clay could not be effectively deflocculated. Therefore slip-casting technique is not possible as a fabrication technique. Alternatively hand throwing on the potter's wheel or jiggering could be effectively used as a fabrication method. The actual size samples, made by hand throwing on the potter's wheel exhibited good properties. For fabrication of glazed red clay items, it was observed that the coefficient of thermal expansion of clay was lower than commercially available leadless low maturing glazes. However by adding sufficient amount of quartz to the clay, coefficient of thermal expansion can be improved.