D Bouchette on sat 30 dec 00
I know it's a glaze, not a slip, but --probably by multiple accident-- I
found a really beautiful navy glaze. It's an accident because, for one
thing, it's from Tom Coleman and it's supposed to be fired in reduction;
second, I think there *might* be a misprint in his book, because the cobalt
amount seems rather high for the color he's going for; and third, I
probably mistook the amount of copper he intended because he doesn't always
use leading zeros.
Try this at cone 9-10 oxidation on porcelain or a smooth, white-firing
clay. It's a great, deep, glossy navy blue. It'll break on sharper edges
and show the clay color underneath (which is why a white porcelain works so
well). Don't use it sparingly; unevenness will show. I've sprayed on
additional glaze on warmed, already-fired pieces and had great results with
re-firing, getting rid of uneven spots. I generally fire my electric to
its cone 9, medium speed, with a 20 to 60 minute soak at the end, depending
on how much ware is in it.
(from "Glazes I Use" by Tom Coleman, entitled "Purple Maroon")
Custer 49.26
Silica 24.63
Whiting 7.88
Dolomite 4.93
Gerstley 4.93
Barium carb 4.93
Zinc ox 2.46
Tin ox 0.99 (adds up to 100.01, not 100.00 as Tom's book says)
and add
Copper carb 2.0
Cobalt carb 2.4
Enjoy!
--deb bouchette
....re-decorating the house because our son turns 14 on New Year's Eve...
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