Porcelain

[kenk]

Looking to identify  a translucent porcelain to be used for slip casing & mold making.  Any suggestions would be helpful.

 

[Mark C.]

Are you looking for a commercial product in the USA?Fired to what temp? cone 06? 6? or cone 10?

[kenk]

no need for a commercial product & i live in the USA. I can fire both 06 or 10 , so would like to use the most translucent  clay possible.

Thanks, Ken

[Bryan Johnson]

Can I play too?  I'd like a cone 6 translucent body with 12% shrinkage. 

So far NZ kaolin, silica, neph sy, and vee gum t  are the whitest/most translucent, but about 18% shrinkage.  Using POE, instead 0f Vee Gum T reduced shrinkage, and cost.

Adding about to a fifty fifty mix of the above two a third of a body based on EPK, #6, Champion Ball Clay, neph sy, silica, and bentolite L yields a much lower shrinkage, and better feel.

 

 

 

 

[neilestrick]

Your basic formula for a cone 10 porcelain is:

• 25% Feldspar
• 25% Silica
• 50% Koalin

Whiteness will be determined to a good degree by which kaolin you use. Grolleg would be great, but you can achieve translucency with domestic kaolins as well. The big issue with casting the recipe above is that it has very low dry strength to start with, and casting makes that worse. So you may want to substitute some ball clay for part of the kaolin. Be very careful with casting slip recipes, as the low clay content of porcelain requires a lot less water than stoneware bodies. Don't add your water/deflocculant mixture all at once.

[Min]

Just in case you haven't come across them already there are 4 high fire casting porcelain recipes plus 1 for mid-fire in here. Also some throwing porcelain bodies. Be interesting to see some of those recipes made up with NZ halloysite and compare the differences in translucency and whiteness to grolleg and domestic kaolin bodies. 

[Mark C.]

I have a casting formula in studio -I'll look for it after the 24th.

To busy with sales right now to get to it. On the Home stretch  now

[glazenerd]

Translucency in porcelain is the result of glass content and molar content of titanium. Kaolin are naturally low in iron and magnesium, but higher in titanium. Once you cross the 0.50% molar content of titanium; translucency begins to diminish. Once you cross 0.90% of Ti02, fired whiteness likewise begins to diminish. To achieve higher glass content.; then at minimum the body requires an additional ten percent  flux content. At cone temps below 7; frit can be substituted to increase glass content as well. When the cone drops down to the 04 range, as much as 1/3 of the recipe can be frit. Although still classified as porcelain if the primary clay is kaolin: in reality the recipe has crossed into the frit ware arena.

If you want to understand plasticity: read "Cation Exchange" in the jan. 2018 Ceramics Monthly. There are traditional and non-traditional ways of achieving plasticity.