Gary Elfring on thu 10 feb 05
For reasons known only to local clay suppliers, I'm having a hard time
finding any reliable sources for porcelain clay within driving
distance of my home. I fire to cone 10 in a gas (reduction)
environment.
Two of my friends have the same problem. We are considering getting
together and making our own porcelain instead of buying pre-made. We
have access to a mixer the local college uses to mix stoneware. They
start with 100 pounds of dry ingredients and add scrap stoneware (wet)
to that for their standard batches. We also have access to a de-airing
pupil that the same school never uses for anything.
My questions are-
1) How much wet porcelain (about) do you get if you start with 100
pounds of dry ingredients?
2)I have a ton of porcelain clay recipes from the USC Clay and Glaze
compendium. I'm thinking of using either the Tom Coleman (cone 8 - 11)
recipe or the Anderson Ranch recipe. Anyone have any experience with
either?
3) I see most recipes call for Grolleg and some calling for Grolleg
China Clay. Is China Clay the same thing as Grolleg?
--
Best regards,
Gary
mailtoandrew@FSMAIL.NET on fri 11 feb 05
Hello Gary,
Probably lost of others are pitching in with answers to your questions but
just on the off chance no one else does:
1) How much wet porcelain (about) do you get if you start with 100 pounds
of dry ingredients?
... Assuming you have no losses (say residue on a sieve or dropped on the
floor!) this is a simple percentage calculation. For throwing you might
want to be around 23% moisture, this will vary according to raw materials
used and personal preference, 100 pounds dry will give a shade under 130
pounds in a plastic condition.
2) I have a ton of porcelain clay recipes from the US Clay and Glaze
compendium. I'm thinking of using either the Tom Coleman (cone 8 - 11)
recipe or the Anderson Ranch recipe. Anyone have any experience with
either?
... I ve no experience myself so hopefully others can help you
3) I see most recipes call for Grolleg and some calling for Grolleg China
Clay. Is China Clay the same thing as Grolleg?
... China clay, sometimes also called kaolin, is the name for a
particular type of clay. Many different china clays are produced with each
having trademarked names, an example is Grolleg which is a china clay from
England. Grolleg is good for porcelain, not least as it has almost quite
low Fe2O3 present and almost no TiO2; these two need to be minimised for
porcelain to be white and translucent. If you want the very best china
clay for porcelain try Super Standard Porcelain; its very strong, plastic,
has almost no TiO2 and nearly half the amount of Fe2O3 as Grolleg.
Hope that s of some help,
Regards,
Andrew
David Beumee on sat 12 feb 05
> 2)I have a ton of porcelain clay recipes from the USC Clay and Glaze
> compendium. I'm thinking of using either the Tom Coleman (cone 8 - 11)
> recipe or the Anderson Ranch recipe. Anyone have any experience with
> either?
Hi Gary,
From my experience the Anderson Ranch recipe would be a good place to start.
The recipe that I have is:
27 #6 Tile clay
27 Grolleg
19 Custer feldspar
13 silica
13 pyrophyllite (Pyrax)
2 bentonite
This body throws better than the original recipe, an all Grolleg mix, because the Tile 6 has a naturally occuring bentonite in it that lends alot of plasticity and workability to the clay body. Unfortunately the Tile 6 also adds iron and titanium content not contained in the Grolleg, so the fired result is a bit darker. Be sure to use a "200" mesh silica, like Silica 90 from U.S.Silica. I highly recommend you replace the bentonite with Veegum T or Bentone MA, as most commercially sold bentonites are loaded with iron. Veegum and Bentone are very expensive, but because you will have a comparatively plastic kaolin, Tile 6, in the recipe, you can cut down the percentage of Veegum or Bentone to 1%. Be sure to mix any plasticizers WET by filling a 5 gallon bucket with warm water and slowly sprinkling in the Veegum, as your partner slowly mixes the water. Let sit overnight.
Add all dry ingredients to the clay mixer and mix dry before adding the water/plasticizer mixture. Add small amounts of additional water to taste. You can also add 0.3% Epsom Salts, 136 grams/100 pounds clay body mixture, IN SOLUTION, for the coup de grace. It's best to add enough water to mix a little on the wet side, and after pugging, leave the clay for two weeks to allow it to absorb moisture and temper. Let me know how it comes out.
David Beumee
davidbeumee.com
Lafayette, CO
-------------- Original message ----------------------
From: Gary Elfring
> For reasons known only to local clay suppliers, I'm having a hard time
> finding any reliable sources for porcelain clay within driving
> distance of my home. I fire to cone 10 in a gas (reduction)
> environment.
>
> Two of my friends have the same problem. We are considering getting
> together and making our own porcelain instead of buying pre-made. We
> have access to a mixer the local college uses to mix stoneware. They
> start with 100 pounds of dry ingredients and add scrap stoneware (wet)
> to that for their standard batches. We also have access to a de-airing
> pupil that the same school never uses for anything.
>
> My questions are-
>
> 1) How much wet porcelain (about) do you get if you start with 100
> pounds of dry ingredients?
>
> 2)I have a ton of porcelain clay recipes from the USC Clay and Glaze
> compendium. I'm thinking of using either the Tom Coleman (cone 8 - 11)
> recipe or the Anderson Ranch recipe. Anyone have any experience with
> either?
>
> 3) I see most recipes call for Grolleg and some calling for Grolleg
> China Clay. Is China Clay the same thing as Grolleg?
>
>
> --
> Best regards,
> Gary
>
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