Chemical composition of clays for pottery in Malaysia: a review

Pottery in Malaysia is been known for its utilized functions and unique properties. Clays
as the pottery’s raw materials are a major factor that affecting the quality and reliability
of some pottery products. Observations on clays’ elements and phases are very helpful
for productions of the good pottery. Hence, in this review, chemical compositions of
clays in terms of elements and phases structures are discussed. Basically, the most
elements found in clays are Si, Al, Fe, Ti, K and Ca. Depends on location, the
concentrations for those clays elements in Malaysia are at range of 24.8 – 32.4 for Si,
10.8 – 19.0 for Al, 0.09 – 2.12 for Fe, 0.08 – 1.13 for Ti and 0.45 – 3.39 for K. Several
studies reported, they exist in form of oxide compound which are SiO2, Al2O3, Fe2O3,
TiO2, MgO, CaO, Na2O, K2O and P2O5. The percentages of elements in clays do not only
determine the clays characteristics, but also influence the physical, mechanical and
chemical properties of the end product. Increase of major element like silica arises the
melting point, lowers the fluidity, and enhances the hardness and tensile strength.
Meanwhile, increase alumina content enables the green body to withstand the sintering
temperature and also increase the hardness of the pottery.