Carbon coring

A phenomenon in ceramics where, during firing, certain parts of a piece pick up a higher concentration of carbon than others, leading to colour variations in the fired work.

It occurs when there’s insufficient oxygen supply in the kiln during firing, creating a reduction atmosphere. Under these conditions, carbon from organic material in the clay can deposit on the surface, especially where oxygen is most limited, producing dark or black marks on the fired piece. The effect can occur unintentionally or be used deliberately to create decorative patterns or colour contrasts.