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blue gloss turns matt in wood fire?

updated fri 24 oct 97


Pat Chesney on mon 6 oct 97

Hello to the glaze gurus.
We have a lovely bright blue, opaque, gloss glaze that turns matt when we
fire it in the wood kiln. We reduce to get flashing with the unglazed ware.
The blue glaze will sometimes crawl in the wood fire but never will in the
oxid. fire.

In oxidation to cone ten, the glaze is perfect. Bright, dark and shiny.

I will give the formula now and see if someone can tell me how to change it
to get a gloss bright blue in reducing, wood fire. If you have a cobalt
blue for wood fire, I would be grateful for the help.

Custer Feldspar 34.65
Gerstley Borate 9.9
Whiting 14.85
EPK 4.95
Bentonite .99
Cobalt oxide 1

PS. we unloaded the wood kiln today and the samples that were glazed thinly
stayed glossy. I don't understand that.

Also, should we use cobalt carb. for an even blue without speckles? If we
don't let this glaze set for a long time, it will speckle when we want an
even blue.

Thanks for your help.

Pat Chesney
Waco, Texas