Ivor and Olive Lewis on sat 8 jan 05
Dear Fred,
Although you are correct about the lack of science in testing glazes
for heavy metal release what is being done is testing for conformity
to those rules and conventions imposed by authority to protect the
general population.
No one has yet suggested that the refractories of suspect kilns should
be tested for their Lead content or to the depth that the
contamination penetrates into the thickness of the bricks or fibre.
When I read the results of leaching tests I know that it is an
expression of the volume or mass of contaminant which is dissolved in
a prescribed volume of leachate (Acetic Acid ?) of known
concentration in a particular length of time at a specific
temperature. An assumption is then made as to whether this will cause
harm to more than or less than a certain number of people in a general
population, which is a matter of Statistics.
People who are suspicious about past contamination should have the
refractories of a suspect kiln.
Thanks for bringing your point forward.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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