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fw: expansion of clays - rr

updated tue 29 sep 09


Dan Pfeiffer on mon 28 sep 09

For Ror,

Subject: Expansion of clays - RR

Hi Dan - I'm resending this because it bounced back.

I'm not sending this to ClayArt cause I'm on the wrong computer for that
but - the expansion number you get from calculation can only be applied to
glossy or semi gloss glazes - never to slips or clay or matte glazes - in
the case of clay bodies the amount of free quartz and cristobalite has a
great influence on expansion and you cannot calculate that.

I would appreciate you passing this on to the list if you feel comfortable
with that - thanks

I agree that having the recipe of any clay you use would be a great help to
potters - my comment on the subject was only that clay makers will just
never do it - unless you could find a compelling reason for them to do it
and then only some would.

Can you imagine every clay company in the US and Canada signing an
agreement to release their recipes? They can't even agree to publish the
sorrect cone their clays fire to without leaking!

Best regards - RR


Ron Roy
15084 Little Lake Road
Brighton, Ontario, Canada
K0K 1H0