Sue Beach on sat 23 sep 06
I have not posted in awhile, though I have been reading the list daily.
I have been focused on preparing for my home studio sale on Oct. 14. If
any ClayArters would like to stop by, I'd love to meet you. I'm located
outside Muncie, Indiana (USA.) Let me know & I'll send you directions.
I am, of course, nervous about the show and busy busy busy getting
ready: postcards, business cards, brochures, mailing lists, tables,
price tags, pricing pots, cleaning, cleaning, cleaning.... and oh, yeah,
making pottery. Glaze kiln firing today.
I tried a new clay body recently. I had been using a commercial clay
that has manganese specks in it. I loved the way it threw but hated the
way it looked after firing - like the pots had chicken pox. Way too
many specks. So I have been trying other clays from my supplier. The
brown stoneware (Standard 112) is what I decided to try. It also has
specks, but not as many as the chicken pox clay. I threw a batch of
spoon rests off the hump - every one got s-cracks. So ok, maybe that
was just me. I threw several nice big pasta bowls. Took care to
compress, etc. Every one got s-cracks. I was not getting s-cracks with
the chicken pox clay.
I will be looking further for a clay body, I guess. I'm firing to ^6
and need to get my clay from a supplier fairly close by. It costs way
too much to have it shipped (doubles the price).
Sue Beach
BeachWare Pottery
Muncie, IN
William & Susan Schran User on sat 23 sep 06
On 9/23/06 10:07 AM, "Sue Beach" wrote:
> I tried a new clay body recently. I had been using a commercial clay
> that has manganese specks in it. I loved the way it threw but hated the
> way it looked after firing - like the pots had chicken pox. Way too
> many specks. So I have been trying other clays from my supplier. The
> brown stoneware (Standard 112) is what I decided to try. It also has
> specks, but not as many as the chicken pox clay. I threw a batch of
> spoon rests off the hump - every one got s-cracks. So ok, maybe that
> was just me. I threw several nice big pasta bowls. Took care to
> compress, etc. Every one got s-cracks. I was not getting s-cracks with
> the chicken pox clay.
The clays with manganese specks are produced to simulate the iron spotting
effects produced in reduction firing. I never cared much for the results and
often found the manganese would cause sticking to kiln shelf issues.
I didn't encourage my students to use these clays when we fired at ^6
oxidation, but I didn't see many "s" crack issues with these clays.
You'll need to compress the bottoms of your pots, inside & outside and try
yo use less water when throwing.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
sacredclay on sat 23 sep 06
We've used standard 112 alot in teaaching our classes at the Jewish
Community Center. It's actually used alot in our town. It's a great
throwing clay. I've never really had trouble with the dreaded S
cracks except when I'm doing off the humps, so I know it's the
technique that I'm using that must be at fault. The one with the
chicken pox sounds like Speckled Brownstone, which I LOVE because of
the earthiness of it.If you're getting s cracks in bowls, you might
be letting them dry too fast, especially if they're large bowls.I
always throw a plastic on top to slow down the drying. It might be
just the particular batch that's bad. Sorry you're having trouble.
Kathryn -- In clayart@yahoogroups.com, William & Susan Schran User
wrote:
>
> On 9/23/06 10:07 AM, "Sue Beach" wrote:
>
> > I tried a new clay body recently. I had been using a commercial
clay
> > that has manganese specks in it. I loved the way it threw but
hated the
> > way it looked after firing - like the pots had chicken pox. Way
too
> > many specks. So I have been trying other clays from my
supplier. The
> > brown stoneware (Standard 112) is what I decided to try. It
also has
> > specks, but not as many as the chicken pox clay. I threw a
batch of
> > spoon rests off the hump - every one got s-cracks. So ok, maybe
that
> > was just me. I threw several nice big pasta bowls. Took care to
> > compress, etc. Every one got s-cracks. I was not getting s-
cracks with
> > the chicken pox clay.
>
> The clays with manganese specks are produced to simulate the iron
spotting
> effects produced in reduction firing. I never cared much for the
results and
> often found the manganese would cause sticking to kiln shelf
issues.
>
> I didn't encourage my students to use these clays when we fired at
^6
> oxidation, but I didn't see many "s" crack issues with these clays.
>
> You'll need to compress the bottoms of your pots, inside & outside
and try
> yo use less water when throwing.
>
>
> -- William "Bill" Schran
> Fredericksburg, Virginia
> wschran@...
> wschran@...
>
>
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Paul Borian on wed 27 sep 06
that 112 is prone to cracking, i worked at a studio that used if for a long
time. One potter would throw lots and lots of pots and just leave them on
the bats to dry without ever trimming them and he had lots of cracks.
Another potter made less pots but always took the time to flip them over to
dry more even and trim them and also cover platters to dry slower and he
got a lot less cracks than the first one. I observe this so many times that
i can say it is an established fact - with very plastic clays like 112 you
have to take care during the drying process or they will crack. There were
also a lot more cracks (from both potters) when the heat or a/c was on -
but still a lot more cracks from the first potter than the second.
-Paul
Ivor and Olive Lewis on fri 29 sep 06
Dear Paul Borian,=20
An interesting conclusion.
How does this correlate to the proportion of water in that particular =
clay body and to its mineral composition ? Does it contain a high =
proportion of bentonite.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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