Kiln setter recipe without talc

[hgclayworks]

I work at a community pottery studio and we’ve had success in the past using Glynnis Lessing’s recipe ( in the July/Aug 2017 issue of Pottery Making Illustrated) for kiln setters, using mullite, ball clay, and talc. Does anyone know of a substitute for the talc in this recipe or have an alternative recipe? We want something that can be fired repeatedly to Cone 10.  

[PeterH]

13 minutes ago, hgclayworks said:

we’ve had success in the past using Glynnis Lessing’s recipe ( in the July/Aug 2017 issue of Pottery Making Illustrated) for kiln setters

Just for reference
https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-article/In-the-Studio-Make-Your-Own-Kiln-Setters

BTW "Start with a 4545-gram batch of the Mullite Setters dry mix (recipe on page 11) and add it to 32 ounces of water" makes more sense when you realise 4545g is close to 10 lb.

[Min]

Hi @hgclayworks and welcome to the forum.

This could be a tricky question to answer. Which talcs do you have access to? 

[hgclayworks]

Talc is not readily available in the US at the moment, so I’m looking for a recipe without talc.  - Thanks for your reply!

[Min]

1 hour ago, hgclayworks said:

Talc is not readily available in the US at the moment, so I’m looking for a recipe without talc.  - Thanks for your reply!

Looks like Brackers still has some AmTalc in the US

https://shop.brackers.com/talc-amtal-c-92-texas/

 

 

[neilestrick]

Also try US Pigment. They still show talc on their website.

[Kelly in AK]

Seattle Pottery Supply says they have some talc as well.

Now, this next bit is information not advice, because I’ve never made kiln shelves and don’t personally  know anyone who has. Alumina and zircopax are both highly refractory, much more than talc. My experience (only to cone 6, mind you) is that zircopax sinters together significantly harder than alumina. 

My opinion is that I would rather chop existing kiln shelves into the shapes I need or buy them than to try and make them. That is, I suppose, because I now have more shelves than I need, and a day job. When I had no money, lots of time and lots of clay, making my own bricks to build a kiln worked out just fine. That was against the opinion of people more knowledgeable and experienced. People can have different opinions and both be right. 

As for advice I would say first to check if Michael Cardew had anything to say about making kiln shelves in his book “Pioneer Pottery.” You can take anything in there to the bank. Next, find a video of Isaac Button loading his kiln. He made his own shelves. Finally, take a look at Tony Hansen’s Digitalfire website. He’s made his own shelves too. 

Please let us know how things work out, I’d like to think we’re learning and teaching together here. 

[Callie Beller Diesel]

Tony’s experiment with kiln shelves was pretty cool, but I think it’s more of a “check out this cool thing this material does” exercise. My supplier’s current price for a 50 lb bag of zircopax is about $350 Canadian. The largest full round shelf they sell as a stock item (26.5”x 3/4”) is less than half that. 

[oldlady]

just a question from a cone 6 user.  what is a kiln setter?  i skimmed the article and see the pictures, is it also known as wadding?  the stuff used in cone 10 firings?  or maybe it is used as a plate or tile rack?   i see that it is not the usual mistake of calling a kiln SITTER  a kiln SETTER.   what are they for?

 

[PeterH]

1 hour ago, oldlady said:

just a question from a cone 6 user.  what is a kiln setter?  i skimmed the article and see the pictures, is it also known as wadding?  the stuff used in cone 10 firings?  or maybe it is used as a plate or tile rack?   i see that it is not the usual mistake of calling a kiln SITTER  a kiln SETTER.   what are they for?

 

Setter is a name for types of kiln furniture which offer some protection against slumping/distortion.

https://www.earthwaterfire.com/products/setters/
Ceramic Setters are special items of kiln furniture which, in the ceramic tableware industry, are shaped (generally on their upper surface) to conform with the undersurface of plates and dishes and which serve to support ware and maintain its shape in the kiln during

 

Setters are especially important when firing bone china.
https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-article/Tempting-Transparency#
In cases where the bisque firing is much higher than the glaze firing, as is normally when working with the case with bone china (between 2246–2300°F (1230–1260°C)), it’s essential that the clay ware receives the maximum support during the firing process, particularly as most of the movement occurs when the kiln reaches its highest temperature. Due to the high distortion factor encountered with bone china, if the shape is to be controlled, any open form requires a setter of some kind.

If the form is circular at the top, it can be placed upside-down on a refractory clay ring, or setter, with an alumina wash to prevent sticking in the firing.

If the form is irregular at the top edge an individual setter needs to be made. In simple terms, this is an item that resembles a lid and is cast separately (the preferred making method for bone china). Its function is to contain the top edge, or rim, of a form during firing (figure 10) and is discarded afterward. If the piece has been successfully fired with no distortion, the ware can be glazed and fired at a lower temperature of 1832–1976°F (1000–1080°C), if necessary.

 

[Min]

I find setters helpful to reduce the number of kiln shelves I need to use if I have a few platters to fire and not a lot of shallow pots to fill the area around them on a regular shelf. Stack of 3 or 4 setters on the bottom kiln shelf with tall pots next to them then continue loading the kiln as usual.

[hgclayworks]

Thanks for the comments everyone. After doing more research and making some calls, I did find sources for talc. I'm in Central Florida and the 2 local distributors are not carrying talc, but I found other sources if I'm willing to pay shipping, (which is considerably higher than the cost of the talc). It looks like Texas talc will be in short supply or unavailable in the foreseeable future, but there are other sources such as Montana talc and Canadian talc which should work for the kiln setter recipe. (Montana talc does not fire as white according to my research, but that would not be an issue in this recipe.)

Kelly, thanks for the suggestions to research. I took a look at Digitalfire and found a few posts regarding kiln shelves, one recipe made with 80% Zircopax, one using Pyrax and Kaolin, and a third using calcined alumina.  https://digitalfire.com/picture/xepfutezaf  Here's the link in case anyone is interested in looking further into that. - I don't have access to Michael Cardew's book, unfortunately.

I'll let you all know if I find any other information.