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: glaze expansion (technica)

updated mon 15 oct 07


Ivor and Olive Lewis on sat 13 oct 07

Dear John Sankey=20

You say in your notes on the derivation of Coefficients of Expansivity =
<<.....50% of his test glazes used lead, which no potter can now =

I imagine this is true in the sense that those glazes made many decades =
ago from which data was derived would not pass scrutiny using the =
standards for Lead and Heavy metal release. But I am sure there are =
commercial glazes that are used to glaze domestic wares which would not =
release levels of lead that would exceed permitted leaching standards.

I suggest it would be unwise to use Lead oxide fluxed gazes without =
having them tested for leaching by an accredited laboratory.

Best regards,
Ivor Lewis.
South Australia.