Definition: Vitrification is the process of melting that different types of clay and glazes go through as they are fired. In a fully vitrified clay-body, the spaces between refractory particles are completely filled up with glass, fusing the particles together and making the clay body impervious to water. Check the manufacturer for the correct firing schedule Ensure your kiln is firing to the correct temp, old coils can cause problems Add glaze to the piece and fire it again at a higher temp Change clay-body for future pieces Using an improperly vitrified clay-body can cause "crawling" and "pitting", not all glazes will react the same
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