Porcelain goes into kiln at least twice. In the beginning. it is baked at 900°C while the temperature in the second baking is increased to about 1300°C. If a product needs over-glazing, it will be treated in kiln for the third time at the temperature of 800°C.
This Arita porcelain on the right went to kiln once while one on the left was baked twice. As an item can shrink about 20% after baking, craftsmen have to shape the item taking into account shrinking ratio. When a glass component in the shaped item melts under high temperature, gaps between clay particles are sealed. Given that process is labour-intensive and outcome is dependent on the expertise of craftsmen, the every product is testament to the skill and deftness of artisans in Arita.