search  current discussion  categories  techniques - misc 

ordering ahead and mixing clay

updated mon 4 nov 02

 

John Britt on sat 2 nov 02


Craig,

We may not have to complain about A.P. Green clay for much longer. A.P.
Green clay is no longer being sold by Highwater Clay Company. (One of the
largest suppliers on the east coast.)

And they have replaced it in their clay bodies. (With Hawthorne Bond I
presume.)

Later,

John Britt

Craig Martell on sat 2 nov 02


Hi:

Great advice from Michael Wendt. I might add, when ordering ahead, buy as
much as you can if any given material is working for you. I just cracked
my last hundred pounder of Kingman spar and ran some fusion buttons thru
the kiln and, VIOLA!, it was the bad stuff. Dirty grey instead of the nice
opaque white spar that makes the blue celadons. Rats! I'm waiting for
Moose Creek Spar to enter into the market. It has more potassium in the
analysis than Kingman and will be great for any glaze requiring potash spar.

Michael grinds the Helmer pretty well. I actually use it in shino glazes
in place of other Kaolins and Ball Clay and I don't get much debris when I
wet screen. Helmer adds some really nice color and "character" to the
shinos too.

With regard to clay mixing, the best clay you will ever use is the stuff
you mix yourself once the recipe is worked out. I had my porcelain mixed
commercially some years back and it just wasn't the same stuff. Problems
with the working properties, glaze fit, getting them to mix and deliver
when I needed clay etc. I mix the stuff myself now and am much
happier. It takes about a day and one half to mix 2400 lbs. I used to do
a ton a day but that was in my younger years.

regards, Craig Martell Hopewell, Oregon

David Beumee on sun 3 nov 02


Dear Craig,
I have not tested Kingman spar as I didn't know it had been available for some time, but the fusion button test of
Moose Creek spar I fired to cone 11 in reduction along side G-200 and Custer showed an uneven and incomplete looking
melt with a few iron spots, compared much more even and homogenous melts from both G-200 and Custer. G-200 showed
a slightly stronger melt than Custer, with no iron spotting in either, so I can get more complete melting action in my clay
bodies with G-200 and use less spar than is required with Custer, meaning that a greater percentage of plastic materials
can be included in the recipes.


David Beumee
Earth Alchemy Pottery






11/2/02 1:20:59 PM, Craig Martell wrote:

>Hi:
>
>Great advice from Michael Wendt. I might add, when ordering ahead, buy as
>much as you can if any given material is working for you. I just cracked
>my last hundred pounder of Kingman spar and ran some fusion buttons thru
>the kiln and, VIOLA!, it was the bad stuff. Dirty grey instead of the nice
>opaque white spar that makes the blue celadons. Rats! I'm waiting for
>Moose Creek Spar to enter into the market. It has more potassium in the
>analysis than Kingman and will be great for any glaze requiring potash spar.
>
>Michael grinds the Helmer pretty well. I actually use it in shino glazes
>in place of other Kaolins and Ball Clay and I don't get much debris when I
>wet screen. Helmer adds some really nice color and "character" to the
>shinos too.
>
>With regard to clay mixing, the best clay you will ever use is the stuff
>you mix yourself once the recipe is worked out. I had my porcelain mixed
>commercially some years back and it just wasn't the same stuff. Problems
>with the working properties, glaze fit, getting them to mix and deliver
>when I needed clay etc. I mix the stuff myself now and am much
>happier. It takes about a day and one half to mix 2400 lbs. I used to do
>a ton a day but that was in my younger years.
>
>regards, Craig Martell Hopewell, Oregon
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>

Craig Martell on sun 3 nov 02


Hello David:

Kingman spar hasn't been available since the 80s. Actually, I've heard
that you can still buy Kingman but it's not the nice 12% potassium Kingman
we used to get. I bought a lot of Kingman and I look for it at potter's
sales, as when they are giving up and selling their stuff. I've bought
seveal hundred pounds this way.

The first fusions I did with Moose Creek spar were kinda bumpy too. I
ground and screened the stuff and redid the fusions. They were much
better. They haven't really started to process Moose Creek yet so the
preparation won't be as good as g-200 and Custer. I'm sure this will
change when the stuff goes into heavy production.

regards, Craig Martell Hopewell, Oregon