Geoffrey Gaskell on sun 18 dec 05
When I accidentally squashed a small cylinder form which was going to
be just a cylinder, the altered form 'suggested' a small jug could be
made with a long-face under the pouring lip. I proceeded with this plan
and after attaching the handle I thought there was something decidedly
fishy about the entire shape. This first item I left as it was. However
I am now deliberately making these forms with anthropomorphic faces &
the addition of fins, gills & fish tails on the handles. I call them
"Fish-or-man Jugs". The original 'mistake' & the first prototype were
decorated with a commercial clear glaze to which I've added a little
copper carbonate & were fired in an electric kiln resulting in what
seems to be a rather effective mottled green & clear pattern. I was
very pleased with the outcome of these two pieces.
Two more "Fish-or-man Jugs" were in my opinion ruined when I tried
another glaze consisting of a commercial white glaze with a little
chrome oxide & a smaller quantity of manganese dioxide added. This
glaze worked well on the test tiles in which I learned that it would be
most effective if it were applied either by pouring or immersing the
pieces in the glaze. Either of these techniques ensured that the glaze
would be a slightly greenish tan (almost kharki) with dark brown specks
here & there. Unfortunately the glazes didn't work that way on the
actual pieces & were seriously flawed by bubbles in the glaze.
According to Casson's "The Craft of the Potter" this pinholing &
bubbling is caused by "certain materials, particularly manganese
dioxide & barium carbonate, [which] will sometimes cause bubbles,
especially, though not exclusively, when they are used in large
quantities. Their behaviour tends to be erratic; nine firings of a
barium- or manganese- bearing glaze may be successful, but the tenth
may produce a badly blistered surface."
I think I'll stick to my original copper bearing clear glaze.
Geoffrey Gaskell
http://www.geoffreygaskell.co.nz/
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Geoffrey Gaskell on sun 18 dec 05
Further to the previous posting, another "Fish-or-man Jug" was ruined by
carelessness in applying the glaze. As a base I used the same white
commercial glaze as that mentioned above & added a little chrome oxide & a
smaller quantity of copper carbonate. The result in the electric kiln firing
was a very nice uniformly speckled blue-grey. The glaze obviously needed to
be applied more carefully (or perhaps the viscosity of the glaze was simply
incorrect for my purpose) because although the glaze would have looked fine
on a straightforward form, it filled in far too much of the details of the
faces & fins etc.
Geoffrey Gaskell
http://www.geoffreygaskell.co.nz/
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