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Mixing porcelain clays


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#1 Essaily

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Posted 15 November 2012 - 11:59 PM

I would like to mix a porcelain clay body with a stoneware clay body.
Has anybody tried this before?
What happens after a bisque fire?
Which temperature do you follow for the bisque & glaze fire - the porcelain body or the stoneware?
When it comes to glazing, can I use an earthenware premixed glaze on this mixed body?
Will it be food safe if I leave it unglazed?

Thanks for any advice most welcome! I haven't a clue.



#2 bciskepottery

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Posted 16 November 2012 - 06:53 AM

Many clay manufacturers sell a blend of porcelain/stoneware, often a 50/50 mix. Look for compatibility in shrinkage; do some small test batches and bisque and glaze fire to see how they perform before going an committing yourself to large amounts. I would mix cone 6 porcelain with cone 6 stoneware, cone 10 porcelain with cone 10 stoneware.

Foods safe for unglazed will depend on firing to maturity and surface and what is in the clay bodies . . . something that is rough and pitted, or carved, will offer hiding places for bacteria to grow and fester. You can always put a napkin or other item between food and surface. Restrict yourself to non-liquids, etc. Foods may stain the surface.

#3 clay lover

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Posted 16 November 2012 - 08:49 AM

I often mix a % of porcelain, ^6, in with my ^6 stoneware clay to get better throwability, or lighten the color, or reduce the speckles of the stoneware. Sometimes I leave it only semi-mixed, and have swirles in the light-dark clay that make a good look on the finished piece.

#4 Essaily

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Posted 17 November 2012 - 05:46 AM

Thanks all for your informative posts! I looked at the packaging and noticed it is already mixed with stoneware. Let's see what happens.




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