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sorry not finished copper red

updated sun 10 jan 99


Theodore Banton on thu 7 jan 99

Custer- 31
Whiting- 7
Flint- 31
Frit 3134- 31
Plus 3% of mix
Copper Carb- 5
Tin oxide- 50
Silicon Carbide- 5.6
Custer Feldspar- 39.4

Please help, I dont know what is wrong.

Ted in Cold St. Augustine

Craig Martell on fri 8 jan 99

Hello Ted:

You don't really say what the problem is but I would assume that the glaze
ain't red. If that's the case I wouldn't worry too much because there
aren't very many copper red glazes that work well in an electric kiln.

I worked out the values for the 3% addition for color in your glaze and the
copper and silicon carb didn't come out in the usual percentage for elec
reds. You could add the following by percentage weight and see if things
look better. 0.5 to 1.0 copper carb, 1.0 silicon carbide, 1.0 to 2.0 tin

Another thing to try is: Make some tiles and coat them with a porcelain
slip with about 4% copper carb. Then apply your copper red glaze. This
will usuall give some acceptable reds in electric. The silicon carbide
tends to migrate downward in fluid, low viscosity reds and will contact the
copper slip beneath, enhancing the color. On upright pieces you will always
be fighting gravity I think. I've gotten good reds on flatware at cone 10
ox but the vertical pieces were never acceptable, until I solved the problem
by firing reduction! :>)

Craig Martell in Oregon

John Post on fri 8 jan 99

At 09:22 AM 1/7/99 EST, you wrote:
>----------------------------Original message----------------------------
>Custer- 31
>Whiting- 7
>Flint- 31
>Frit 3134- 31
>Plus 3% of mix
>Copper Carb- 5
>Tin oxide- 50
>Silicon Carbide- 5.6
>Custer Feldspar- 39.4
>Please help, I dont know what is wrong.
>Ted in Cold St. Augustine

Hi Ted,

You didn't say what was wrong with this glaze, but I'm assuming that it
isn't coming out red. The silicon carbide in this glaze is supposed to
provide localized areas of reduction and thus turn the copper carbonate
red. In my experiments with silicon carbide in an electric kiln I have
noticed that the silicon carbide doesn't stay evenly dispersed in the
glaze. On a vertical pot you won't see hardly any red. This glaze will
yield some raspberry red patches if you use it to line the inside of bowls.
Try this glaze on some flat pieces to see the red develop. This glaze
will not end up looking like the copper reds you can get in reduction
firings. I'll be interested to hear if anyone else has had better success
with this type of glaze.

John Post
Sterling Heights, Michigan USA

Veena Raghavan on sat 9 jan 99

If you don't mind, could you post the cone for this copper red
glaze. I''m assuming it's a high cone but hoping it might be cone 6 (ever
wishful of getting red at cone 6). Thanks in advance
Veena Raghavan