Geoffrey Gaskell on mon 10 may 04
Some time ago Nana Underhill enquired about some modifications to the
Glaze Recipe under the heading Crystal Glaze Drips.
I created some of this stuff, but found the result somewhat
disappointing since, at 1250 celsius in an electric kiln it seemed to
become more or less absorbed into the clay body. Being naturally
inclined towards alchemy & not in the least bit concerned about the use
of certain metal oxides, I decided to apply a manganese oxide flavoured
slip to the entire surface of a sacrificial pot, then apply the crystal
glaze over the top of that. When fired to 1250 celsius in an electric
kiln, the result was a rather pleasant matt predominantly light
yellowish brown surface with semi gloss random mottles of darker
yellowish brown.
I was going to repeat this on some decent pots, but had run out of the
manganese oxide, so I substituted a chromium oxide slip, which if
anything, produced an even more remarkable effect in the electric kiln
at 1250 celsius: it looked like it had been raku fired! There was an
entirely matt finish, predominantly pinkish orange with some patches of
light green or yellowish green and several patches of very dark (almost
black) green.
I then decided to make up some manganese oxide flavoured slip put a
layer of this on a pot, then a layer of the chromium oxide slip &
finally the layer of crystal glaze over the top and once more fired it
in the electric kiln at 1250 celsius. The result was a matt dark brown
with very little variation, but not unpleasant to behold.
Such then were the results of my messing around intuitively rather than
scientifically, though I have taken careful note of the results for
future reference.
Geoffrey Gaskell
http://www.homepages.paradise.net.nz/ggaskell/
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