Ken Russell on tue 27 feb 01
My pinholing problem has magically disappeared, thanks to Ron Roy and Betsy
Price. For those with future problems with it, this may help:
The slow rate between 1000F and 1600F in the bisque seems to have done the
trick. I went from 1000F to c05 at 80F per hour and it apparently burned
out every carbon atom in the place. The clay body is Tucker's Midcal 5(with
a nice manganese added for specks), the glaze was the Hansen 5X20 without
any tweaking to the 3134 or the EPK (Ron, I had so damn much 5X20, I
couldn't force myself to mix up the 18% EPK and 22% 3134).
The glaze fire was done with the Skutt's standard computer slow fire
schedule (No Ron, I haven't got the cones yet but I will, I promise.). I
changed the bisque fire schedule only and nothing else just to find out
exactly what I was doing wrong. If the bisque hadn't worked, I would have
tried a slower glaze fire, with a longer soak. If that hadn't worked, then
I'd have tried the meltier Hansen (18% EPK, 22% 3134 and the rest of the
stuff at 20%). Well, the bisque worked and worked very nicely. The glaze
fire turned out quite well with not a pinhole to be found.
FWIW, Tom Wirt and Betsy Price saw the "pinholed" stuff at Rosen and thought
it was not really pinholing at all but more of an orangepeel type deal which
occurred over the metal oxides. And, it really wasn't that bad (in fact, I
thought by and large it was a very nice look, only I wanted smooth. If you
want a quite stunning orangepeel-like effect, let me know and I can tell you
how).
To add a cent or two to the person with Hightower Clay cracked platters: I
had the same problem as you described with my old clay. Lost about 200-400
bucks monthly on weird platter cracks and distortions. I changed clays and
love the stuff I'm now using. No more platter problems whatsoever. In
fact, I've taken leather hard platters (just to see if it would work),
placed them atop a bisque kiln, then let the bisque quick dry them,
something absolutely unheard of with my old clay bodies (drying times for
old clay platters was two to three weeks of slow, careful drying). Narry a
crack.
Ken Russell
The Russell Pottery
gone2pot@ispchannel.com
Caroline Jacobs on tue 27 feb 01
Hi; I'm having a terrible time with cracks using 4 yr old terra cotta clay. I've patched up and burnished a plate and enclosed it well in plastic abut 10 times now. Could my problem be, as is implied in Ken Russell's email below, that I'm getting cracks because my clay is old??
Thanks a lot.
Caroline in Santa Monica
Ken Russell wrote:
>
> My pinholing problem has magically disappeared, thanks to Ron Roy and Betsy
> Price. For those with future problems with it, this may help:
>
> The slow rate between 1000F and 1600F in the bisque seems to have done the
> trick. I went from 1000F to c05 at 80F per hour and it apparently burned
> out every carbon atom in the place. The clay body is Tucker's Midcal 5(with
> a nice manganese added for specks), the glaze was the Hansen 5X20 without
> any tweaking to the 3134 or the EPK (Ron, I had so damn much 5X20, I
> couldn't force myself to mix up the 18% EPK and 22% 3134).
>
> The glaze fire was done with the Skutt's standard computer slow fire
> schedule (No Ron, I haven't got the cones yet but I will, I promise.). I
> changed the bisque fire schedule only and nothing else just to find out
> exactly what I was doing wrong. If the bisque hadn't worked, I would have
> tried a slower glaze fire, with a longer soak. If that hadn't worked, then
> I'd have tried the meltier Hansen (18% EPK, 22% 3134 and the rest of the
> stuff at 20%). Well, the bisque worked and worked very nicely. The glaze
> fire turned out quite well with not a pinhole to be found.
>
> FWIW, Tom Wirt and Betsy Price saw the "pinholed" stuff at Rosen and thought
> it was not really pinholing at all but more of an orangepeel type deal which
> occurred over the metal oxides. And, it really wasn't that bad (in fact, I
> thought by and large it was a very nice look, only I wanted smooth. If you
> want a quite stunning orangepeel-like effect, let me know and I can tell you
> how).
>
> To add a cent or two to the person with Hightower Clay cracked platters: I
> had the same problem as you described with my old clay. Lost about 200-400
> bucks monthly on weird platter cracks and distortions. I changed clays and
> love the stuff I'm now using. No more platter problems whatsoever. In
> fact, I've taken leather hard platters (just to see if it would work),
> placed them atop a bisque kiln, then let the bisque quick dry them,
> something absolutely unheard of with my old clay bodies (drying times for
> old clay platters was two to three weeks of slow, careful drying). Narry a
> crack.
>
> Ken Russell
> The Russell Pottery
> gone2pot@ispchannel.com
>
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Dannon Rhudy on tue 27 feb 01
..... Could my problem be, as is implied in Ken Russell's email below, that
I'm getting cracks because my clay is old??.....
I believe he meant his "previous clay body" and not that his
clay was old. With clay, the older the better.
regards
Dannon Rhudy
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