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Pat Newman

Porcelain Recipe

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Hi, I'm trying to produce my own porcelain. I began with the most simple recipe

 

15% Caolin

15% white clay

60% feldspat

10% flint

It's to cone 6 1.230° Celsius

 

It stays really white but not to plastic, not flexible, it cracks when I try to bend into a plaster mold, and if I add more water, it turns into mud. What can I do to correct and have a more plastic porcelain so I can have a very thin wall.

Hope someone can help me.

Thanks,

Pat

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Look up 2 articles.

One is called "Body Building for Potters" Can't recall the author. the other is by a guy named Bumee.

I don't recall the magazines. Either Studio Potter or Ceramics Monthly.

 

The basic idea is that you should start with a mixture of clays that work well, then add fluxes to adjust absorption and silica (if needed) to adjust coefficient of expansion.

 

So, for your formula you would need to know the fired absorption and CEO to start so you could try to maintain those figures while adjusting the formula to give better workability.

If you want better workability, the previous post is correct. You will need more clay. How much and what type of clay will be a matter of your desired fired color, working characteristics and testing testing testing.

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check out Jeff Campana's body from clayarts sept 20th of this year.

it is a very good recipe for throwing - good place to start - has the right amt of clay and flux.

enjoy...........

Campana Mid-range Porcelain Cone 6–7

 

EPK Kaolin20%

 

Tile #6 Kaolin15OM4 Ball Clay 10Feldspar 35Silica (325 Mesh)20=100%

Add: Bentonite 3%

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Hi, Pat.

 

If you like this recipe, it fires the way you like and you are using it for press molding, you can try adding about 3-4% hectorite (the two commercial products are Bentone MA and American Colloid Hectolite-200). I agree with the other posters that usually 30% is not enough clay, but if it works for you for your purposes at cone 6, why not? Hectorite is similar to bentonite, but contributes much more plasticity to the clay body although it is pretty expensive. Stay away from calcium bentonites, they don't do much for a clay body. Most sodium bentonites have a lot of iron. To check the effectiveness of a bentonite, mix 10 gm bentonite and 25-30 ml water: If it just stays mud, it won't help much, if it turns into a gell it well help. If you choose to add more clay, you can use a plastic "kaolin" like #6 tile, or add a plastic ball clay, like OM-4, and reduce the feldspar. Good luck!

 

Ray West

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Hi, I'm trying to produce my own porcelain. I began with the most simple recipe

 

15% Caolin

15% white clay

60% feldspat

10% flint

It's to cone 6 1.230° Celsius

 

It stays really white but not to plastic, not flexible, it cracks when I try to bend into a plaster mold, and if I add more water, it turns into mud. What can I do to correct and have a more plastic porcelain so I can have a very thin wall.

Hope someone can help me.

Thanks,

Pat

 

hi, I think your question has been answered- add BENTONITE, it helps to render non plastic materials such as Kaolin, the basis of porcelain (is that your "white clay"?) more malleable. Mix dry with the other ingredients (to avoid the lumpiness of the bentonite on contact with water), add to enough HOT water to produce a slip. Leave to dry in suspended cloth sacks (definitely not on plaster which will reduce it's plasticity). store it for several months, even a year, like good wine it gets better with ageing!

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