Linda Arbuckle on thu 4 jun 98
Norm,
I would be careful using neph sy as the body flux. It can be partially
soluble and deflocculate the clay body. Make the clay particles line up
parallel and slightly repel each other. Clay is hard to work with. Feels
too wet, then dries on the outside, particles sit together, and inside
water has trouble wicking out. Can cause cracking. We tried a recipe w/a
lot of neph sy this spring, and it was just penance to work.
Pete Pinnell gave us this advice:
I don't know a distinct recipe, just some general guidelines. For a
cone 6 light body you need about 20-25% flux with the rest being clay
or a clay/filler combination. Neph sy can work but it will tend to
deflocculate the clay unless it is counteracted with either epsom salts
or calcium chloride. Soda spar or G-200 will also work, but are not as
active so the clay will tend to be a bit more porous. You can also add
just a small amount of talc and that will really tighten up the clay,
but at a slightly heightened risk of cristobalite. The strongest
spar/talc eutectic is at a ratio of five or six parts spar to one part
talc.
As for clay, it can be "to taste". It will stand up a lot better and
crack a lot less if there is some fireclay, though very much will push
the color to buff. Similarly, a little ball clay goes a long way to
promote plasticity. Kaolin will give the whiteness, but you can't use
it alone unless you also add some other filler such as flint or
pyrophyllite. If it were me i would start with the following:
Fireclay 20, ball clay 20, tile #6 kaolin 25, flint 10, kona f-4 spar
25, bentonite 1. This will be pretty off-white (cream to buff), so if
they want whiter they will have to accept the lower workability of a
high kaolin body. They may want to add grog, in which case you could
use something like Ione Grain if they want whiteness without the cost
of Molochite. Kona can also cause deflocculation, so a little
flocculant (one quarter percent) might be a good idea. Have them
dissolve it first in hot water.
This is just a starting point- they can adjust any of the components to
fit their needs.
--
Linda Arbuckle
Graduate Coordinator, Assoc. Prof.
Univ of FL
School of Art and Art History
P.O. Box 115801, Gainesville, FL 32611-5801
(352) 392-0201 x 219
e-mail: arbuck@ufl.edu
Mike Gordon on fri 30 dec 05
Randy,
I use Laguna's Soldate 60 clay at Cone 6-7 all the time, with no
problems. I throw shot glass size's to the full bag with this clay. No
cracking. Mike Gordon
Mike Gordon on fri 30 dec 05
Randy,
I use Laguna's Soldate 60 clay at Cone 6-7 all the time, with no
problems. I throw shot glass size's to the full bag with this clay. No
cracking. Mike Gordon
Teresa Griffin on wed 4 jan 06
I use Laguna's Soldate 60 clay at Cone 6-7 to throw display pieces. I do
not have any problem with cracking.
I like it because it is soooooo easy to work with and it is light weight.
Chaeli Sullivan on wed 24 oct 07
Hello folks
Until now i've been firing stoneware cone 6 clay to cone 6. However,
would like to try out a new Cone 8 glaze and i wondered if i can fire the
clay to Cone 8. Will it survive? Or like earthenware clays melt at the
higher temperature?
Thanks
Chae
Roseanne Breuer on wed 24 oct 07
Contact the manufacturer for the details on your clay firing temperature.
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Nancy on wed 24 oct 07
I think it depends on the clay. I have overfired my cone 6 Laguna clay
(bmix, bmix with grog and #66 as well as standards 206 and the old 245)
and it's been okay. There are ranges for the clay bodies. I'd check
with your supplier for your particular brand of clay.
Nancy
www.hilltoppottery.com
Chaeli Sullivan wrote:
> Hello folks
> Until now i've been firing stoneware cone 6 clay to cone 6. However,
> would like to try out a new Cone 8 glaze and i wondered if i can fire the
> clay to Cone 8. Will it survive? Or like earthenware clays melt at the
> higher temperature?
> Thanks
> Chae
>
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Chaeli Sullivan on thu 25 oct 07
Thanks for the suggestions to call the manufacturer. Did that today and
Seattle Pottery said that their Cone 6 clay can actually fire at Cone 5
but would more than likely have disastrous effects at Cone 8.
So perhaps it's a happy happenstance that the new kiln stalled out at 1900
degrees!
Chae
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