Looking for white, low-fire casting slip recipe for horsehair pottery

[Suresh Sundaram]

Hello,

I am looking for a white, low-fire casting slip recipe that can be used to create horsehair pottery,

When I throw these pieces I use Laguna's #10T earthenware which has worked great. I know I can try and create a casting slip from the #10T but I am hoping to get a recipe using raw materials.

I tried creating the casting slip from my raku clay recipe (33% Hawthorne 35 mesh fireclay, 33% Tile 6 and 33% OM4 ball clay) but (a) it  gels too fast and (b) it is not white enough. I think I have too many plastic ingredients. My next step is to replace the Tile 6 with EPK (less plastic) or Velvacast, and after that the ball clay with FC340 ball clay.

While I do these experiments, I thought I would reach out to this group to see if someone has already been down this path.

I should mention that I have used Laguna's 500L stoneware casting slip but the breakage rate is too high.

Thanks,

Suresh  

 

[Jeff Longtin]

Hey Suresh,

Been down that road but it's been years. No recipes but I do recall most earthenware casting bodies have lots of talc in them.

Did you see that Laguna makes a low fire casting body? MCP Artware. It is described as a "high talc" casting body. I'd try that first.

Good luck

 

[Suresh Sundaram]

Hi Jeff,

Thank you for the tip. I was not aware of MCP Artware.

I am hoping to formulate my own recipe instead of buying one but you have helped me. The MSDS sheet for MCP Artware shows Talc and Kaolin between 25 and 65%, Silica at 10-25%,  Dolomite and Feldspar at 5-10% each and small amounts of Calcium Carbonate and Titanium Dioxide.

Laguna 10T, the earthenware clay which I had pretty good luck with, shows a composition of Kaolin at 25-65%, Talc and Silica at 10-25% each, Calcium Carbonate and Feldspar at 5-10%, Dolomite at <5% and Titanium Dioxide <2%.

In other words the components are the same,  just some of the percentages are different. This gives me confidence that the MCP Artware will work for my situation. (Interesting that there is no ball clay in either).

I am thinking to start  with a simple formulation of Talc 50%, Kaolin 25%, Silica at 15%. Feldspar at 10% and go from there. I will start with the assumption that the Dolomite, Calcium Carbonate and Titanium Oxide are not integral to the formulation. I have never worked with Talc before so I don't know if I have enough plastic materials. If that becomes a problem, I can try introducing ball clay and reduce the other ingredients proportionatety.

Any thoughts or comments would be appreciated.

Suresh  

[Jeff Longtin]

Leon Nigrosh wrote a nice book about "low fire" back in the 70's that I always found helpful.

I think I mixed his recipe but don't remember the outcome. It is: talc 45, ball 19, feld 19, kaolin 17. with soda ash .15 and sodium silicate .15. You could also try it? 

[Suresh Sundaram]

Thanks, Jeff! I would rather start with a published recipe like this than from scratch. 

My local library has the book in “STORAGE.” I’ll see how if they can retrieve it. Sounds like it might be a good resource for me. 

[PeterH]

6 hours ago, Jeff Longtin said:

Leon Nigrosh wrote a nice book about "low fire" back in the 70's that I always found helpful.

Low Fire : OTHER Ways to Work in Clay  Leon I. Nigrosh?

If this is the right book 2nd hand copies seem quite cheap (<$5).

https://www.bookfinder.com/search/?full=on&ac=sl&st=sl&ref=bf_s2_a1_t1_1&qi=jZ9txr1bouNCtZ9PoXMfx.wd7CM_1704364091_1:11533:21043

[Suresh Sundaram]

Thanks, Peter. I don't even think about buying books anymore - the library is such an awesome resource- that I didn't even look!

I found Nigrosh's casting slip recipe on Glazy. It's listed as a glaze! No wonder I didn't find it 'cause I looked at all the casting slip recipes on Glazy few weeks ago.

 

[PeterH]

4 hours ago, Suresh Sundaram said:

I found Nigrosh's casting slip recipe on Glazy. It's listed as a glaze!

There are also a couple of Nigrosh's Egyptian Paste recipes under glazes.

PS Googled site:glazy.org Nigrosh

[Suresh Sundaram]

Good to know, Peter, thanks!