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Firing lead free glazes
Changes In Glazes:
Lead free glazes are becoming the standard for commercial use. This is due to government regulation and health concerns by the manufacturers. As the name implies, lead free glazes are made from compositions or materials where lead has not been added.
To eliminate lead, glazes are reformulated. This can change some of their properties. Some of the differences you may notice include:
Does not flow or run as much in firing as lead-containing glazes.
*Brush marks may show after firing
*Not as wide a firing range
*May not be compatible with as many bodies (improper fit). This leads to shivering or crazing of the glaze.
*Colour does not match lead glazes
*More surface defects
For problem-free results with lead free glazes, firings must be more closely controlled and kilns well vented. Bodies may have to be bisqued to a higher or lower cone number to solve a problem.