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Best clay for outdoors


Ptown artist

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The factor of porosity would be key. If the sculpture absorbs moisture , freezes, water expands, you will get a cracking and shearing off.

So firing to vitrification would be the way to go.

The properties of the clay body which allows you to construct your sculpture best would have to be considered.

I think I read of clay additives which when dried allow the forming of minute cracks around each piece whilst being great to increase tolerance of thermal shock may lead to cracking in instances such as yours.

@glazenerd may be of help

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  • 4 weeks later...

Sorry Babs; 

Just now coming back online; my 15yr old IPad finally said goodnight- was waiting on Santa Claus to show up. Actually, I was waiting for after Santa Claus sales to buy one. 

This has been an ongoing discussion for many years now. There has been numerous references to brick, tile, and other products used outdoors. Brick for example relies heavily upon “black coring” to occur that produces nearly a zero absorption value. Modern talc body tiles rely on the high magnesium content to produce very low absorption rates. Porcelain has to produce enough glass/mullite content to reach a vitreous state. Grog used in brick making is for malleability; in lieu of plasticizers; but black coring still produces the density and nearly zero absorption rate.

So in translation: a red bodied clay must be fired hot enough to create low absorption, or intentionally fired on high speed to produce black coring. Talc body (low fire 04) must have enough magnesium content to produce low porosity. Porcelain at cone 6 must have a minimum of 30% feldspar content to achieve low porosity.  Like anything- have to test final results. 

T

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