Ceramic objects are made essentially from clay and quartz sand - chemically speaking aluminium and silica, raw materials which are as old as the earth itself. Clay is used in powder form. Quartz sand, which is very common in Europe, results from the natural disintegration of rocks containing quartz, like rock crystals present in rivers and the sea, which is composed of silicon dioxide.

Thermoluminescence is suitable only for dating of excavated objects, as it can measure the earth's radiation absorbed by the crystals of the clay body.

Ceramics which have not been buried in the earth, whatever their nature, cannot be dated, save with a margin of error of 200-300 years. This means that a piece of porcelain could just as well be from the 17th as from 19th century.

In order to distinguish porcelain from other ceramic material, there is a simple, reliable and age old test: if one taps one's knuckle on the edge of a plate held only in the middle, a distinct ringing tone tells us it is porcelain. This unmistakable resonance depends on porcelain's extraordinary compact texture.

During the Song and Yuan dynasties porcelain was made at Jingdezhen and other kiln sites in southern China using crushed and refined porcelain stone alone, but by the early eighteenth century china clay and porcelain stone were mixed in about equal proportions. China clay when added to the body material produced a porcelain of great strength and whiteness (whiteness, in particular, was a much sought after property of porcelain, especially that used for blue and white wares).

Porcelain bodies made from porcelain stone fire at a lower temperature, in the region of 1250 degrees Celsius, than those made with a mixture of china clay and porcelain stone, which require firing in the region of 1350 degrees Celsius.

The temperatures within a typical large, southern egg-shaped kiln varied greatly, from hot, near the firebox, to cooler, near to the chimney at the opposite end of the kiln. One advantage gained by the addition in varying amounts of china clay was that the composition of the paste could be altered to suit the position that the wares made from it would occupy in the kiln, with a clay-rich mix being used for wares to be fired at the hot end of the kiln and a stone-rich mix being used for wares to be fired at the cooler end of the kiln.