Highly refractory and non-plastic, flint is a major source of silica in all types of clay body (15%). It increases firing temperature and reduces plasticity and shrinkage. It may be added in small quantities to prepared bodies to eliminate crazing. A major source of silica in all types of glaze (it is the glass forming ingredient), its characteristics of low expansion and contraction stabilise the glaze and minimise any risk of crazing. Adding flint to a glaze raises its firing temperature.