Further Enhancement of Physical Properties of Unglazed Traditional Cookware

Abstract

Red clay is one of the cheapest types of clay commonly found in Sri Lanka. The potsherds and roof tile pieces unearthed all over the island, bear witness to the use of clay for various purposes in the past. The present study explores the possibility of using the fillers and fluxes treated with red clay for the preparation of cookware and tiles. Eight samples of the traditional earthenware were prepared with different compositions. The first three samples were prepared using 15 wt%, 20 wt% and 25 wt% of red clay. Among the prepared three samples, 15 wt% red clay sample found to be best for further studies for improvement of physical properties. The optimized sample was treated with fillers and fluxes of fumed silica, alumina, talc, rice husk ash, and calcite to investigate their physical properties such as density, viscosity, thickness, particle size, drying or firing shrinkage, firing color, loss on ignition, water absorption, and modulus of rupture. It was found that all fillers and fluxes could be used to improve certain important properties of red clay. The optimum firing temperature for all the samples was 800 oC. Results of this study show that all the physical properties of earthenware and tiles have been enhanced comparable with other similar high-quality materials. Findings of this study hence useful for production of quality cookware and tiles for domestic and exportation purposes.