Snail Scott on sat 28 jan 06
At 11:39 AM 1/28/2006 +0100, you wrote:
>...My High Calcium Semimatte with yellow stain came out
>perfectly shiny!>I have a very dolomite/calcium laden matte glaze that is
usually very
>matte that did the same. Does overfiring do that to cal/mag mattes?
Usually these are quite forgiving of overfiring, since=20
the matte effect is formed during cooling. Too-fast=20
cooling is my usual culprit when a microcrystalline=20
matte glaze (calcium or dolomite/magnesium) goes shiny.
The only mattes which generally go shiny with overfiring=20
those which are not 'true mattes', but are actually just=20
higher-temperature glazes fired below their vitrification=20
point. Just because it's relabeled from '^10 gloss' to=20
'^6 matte' doesn't make it so. (That said, although such=20
underfired mattes are a terrible idea on pottery, they=20
can work well on decorative/sculptural ceramics.)
>I will try to fnd hot was resist, but it's basically unheard of here. Is
>there a way to make it yourself? How hot does it have to be to apply it?
There isn't really anything sold as 'hot wax resist'.=20
Almost any wax will do. Old candle stubs melted down=20
will work fine, and block paraffin such as that sold=20
for canning, etc. You can melt it on a crock-pot or=20
other slow cooker - they don't get hot enough to reach=20
a danger point. May people also use electric skillets=20
to melt it - you just have to not let it get too hot.
Double boilers work, too. I don't suggest using a pan=20
on a hot plate - if the wax gets directly on the heating
element, it smokes and can catch fire. (Some waxes=20
melt at hotter temperatures than others, but most are=20
in the 200=BAF-250=BAF range - pretty low.)
Just heat it 'til it melts - that's all you need to do.=20
-Snail
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