Bonita Cohn on sun 23 may 99
If I'm not mistaken, off the top of my head this evening... I believe it is
silicon carbide. Add up to 15% to your glaze for bubbling. Do a line blend to
find the degree you like. Bonita in San Francisco.
Mary Ella Yamashita on wed 26 may 99
I have been interested in the discussion about electric kiln reduction with
silicon carbide glazes. My question is, would these artificial reduction
glazes be hard on the kiln elements? Thanks for any insight--
Mary Ella
>From: Wade Blocker
>Subject: local reductioon glaze
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>----------------------------Original message----------------------------
>Silicon carbide is added to a glaze fired in an electric kiln to create an
>artificial reduction glaze. It is necessary to use a very fine mesh of
>silicoon carbide. FFF grade is 325 mesh, though it is available as fine as
>600 mesh. This can be purchased either from a ceramic supplier or a
>chemical supply store. I have obtained fairly nice reduction reds on
>porcelain clay using the following recipe:feldspar 42%, Kaolin l.8%flint
>26.5%,whiting 2.6%,gerstley borate 8.8%dolomite 8.8%zinc oxide l.7%,barium
>carbonate 4.4% addCu oxide black 0.5%,Cu Carb 0.25%,Silicon carbide 0.4%,
>fired to cone 9 in oxidation.For artificial celadon add 0.5 silicon
>carbide and l.5 red iron oxide to the above recipe and leave out the copper
>of course. If you fire at a lower temperature you have to test the above
>ingredients in a gloss transparent glaze that matures at your firing
>level. Hope this helps.
>
Wade Blocker on thu 27 may 99
Mary Ella, local reduction does not affect kiln elements. The minute amount
of silicon carbide in the glaze changes the usual copper green to red . In
order to get a crater glaze you use more silicon carbide. The glaze I
posted was by Carlton Ball , his Chun glaze. There is a good discussion of
artificial reduction glazes by Emmanuel Cooper in Electric Kiln Pottery,
the complete guide page 95-97. Your local library might have a copy. I hope
this helps. Mia
Paul Lewing on thu 27 may 99
Mary Ella Yamashita wrote:
>
> ----------------------------Original message----------------------------
> I have been interested in the discussion about electric kiln reduction with
> silicon carbide glazes. My question is, would these artificial reduction
> glazes be hard on the kiln elements? Thanks for any insight--
> Mary Ella
Mary Ella,
I don't think the amount of silicon carbide used for local reduction
would have any effect on your elements. Someone said on this topic that
you should use up to 15% SC for this. This is way off- one-tenth that
amount might be too much. If you're looking for a smooth surface rather
than a cratered look, about .5% to 1% is plenty. If you have any ball
clay in your clay body, you probably routinely burn more carbon than
that from firing the organic material in it out. Just not enough
material there to make a difference.
Paul Lewing, Seattle
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