Robert Goode on sun 19 mar 00
Please excuse the interruption, an AOL flash session took place.
To the Saloman base glaze [GB-55, EPK-30, Flint-15] I added, in different
batches,
Red Iron Oxide-6%;
RIO-4+Copper Carb-4%;
Copper Carb-6+Rutile-6%.
To each of these I added first 0.5% Silicon Carbide 500 mesh, then 1% of same.
These glaze batches were applied to test tiles made of high talc white clay
(Byrne's White) with 5% Redart added for clay coloration. Bisque firing had
been to ^06 and glaze firing was also to ^06.
The result:
1) All tiles showed pinholes, blisters and craters, slightly more prominent
with the 1% than the 0.5% SiC.
2) The RIO-6%, which had been brown in an oxidation firing, was medium gray
in local reduction. The rims of the craters were darker gray and the centers
were lighter gray. Beneath the domes of the blisters the glaze was also
lighter gray.
3) The Cu4Fe4, which had been warm green in an oxidation firing, was
grey-olive overall in local reduction. The rims of the craters showed
malachite-green colored deposits at 1% SiC, and darker olive margins at 0.5%
SiC.
4) The Cu6Rut6, which had been light jade green in an oxidation firing, was
milky light green with flecks of mauve-pink at 0.5% SiC and about 60%:40%
mauve-pink:milky light green at 1% SiC. The blister bases were all in the
pink family and were as glossy as the rest of the surfaces. The craters were
rimmed by malachite-green colored deposits.
If there is a right road to successful local reduction, am I on it? Any
suggestions?
Paul Lewing on mon 20 mar 00
Hi, Robert.
I've never had much luck with the artificial reduction thing. Usually
the silicon carbide is too coarse, but it sounds like you've got some
real fine stuff there. However, I've not had much luck with 800 and
1000 mesh either. I did get some of my cone 5 glazes to actually look
like copper red, but I had to refire them up to cone 7 to smooth them
out. I suspect that at cone 06, you just don't have enough heat or
enough time to smooth out the bubbles. And I've never gotten iron to
look reduced at all, and in many years of asking around about it, I've
never found anybody else who has, either. But who knows, maybe you can
be the first. Keep testing!
Paul Lewing, Seattle
Rob Sanders on tue 21 mar 00
Once we got some lovely pinks in a glaze with minimal amt of copper when we
refired it in a little enameling kiln at fairly low temperature and
introduced strips of linoleum and/or crayons through the peep hole. It was
indoors and the smoke emitted was nasty, and probably not good for the
electric kiln, so we didn't pursue it further, but the pots were very nice.
----- Original Message -----
From: Paul Lewing
To:
Sent: Monday, March 20, 2000 8:18 AM
Subject: Re: Local reduction continued...
> ----------------------------Original message----------------------------
> Hi, Robert.
> I've never had much luck with the artificial reduction thing. Usually
> the silicon carbide is too coarse, but it sounds like you've got some
> real fine stuff there. However, I've not had much luck with 800 and
> 1000 mesh either. I did get some of my cone 5 glazes to actually look
> like copper red, but I had to refire them up to cone 7 to smooth them
> out. I suspect that at cone 06, you just don't have enough heat or
> enough time to smooth out the bubbles. And I've never gotten iron to
> look reduced at all, and in many years of asking around about it, I've
> never found anybody else who has, either. But who knows, maybe you can
> be the first. Keep testing!
> Paul Lewing, Seattle
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