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Unidentified Clay


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#1 jasonarp

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Posted 02 May 2012 - 04:51 PM

Hi all,

I inherited a 25 pound bag of gray/silver clay from an event I volunteered at. We worked in a kids art tent at a festival. At the end of the day they had 20 or so bags of this clay left over so they asked all the volunteers to take a bag home (we were all college art students). I was told it "may be low fire clay". I did a little bit of research but I can't find any slivery low fire clay bodies. I asked my teacher if we could test it because he is usually all about testing out new ideas, but this time he was really not into the idea. Does anyone know how I could test the clay? I do not have a ton of my stoneware left, and I want to continue creating over the summer.

Thanks everyone,
Jason

#2 perkolator

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Posted 02 May 2012 - 05:13 PM

test it inside of a pre-fired catch/test tray or saggar if you're worried about it turning into a puddle. tray must be fired first and crack-free. greenware test tray is just a bad idea. you could also ask the kids art staff where they bought the clay - most likely it was bought locally, so you could also ask your local clay suppliers if it looks familiar.

#3 jasonarp

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Posted 02 May 2012 - 06:39 PM

Should any old stoneware bowl work? I believe the clay was donated to the tent.

#4 Mark C.

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Posted 03 May 2012 - 01:23 AM

Put a small amount of the test clay (a small chunk ) in any high fire bisqued piece-It can be a pinch pot to a cup or bowl or a spoonrest-just something to catch the liquid mass of the melted low fire clay piece so it does not spill onto kiln shelves. Fire to cone 6 or cone 10 whatever temp you are working at. If piece is still intact and not melted its high fire if a puddle its low fire.
Test is easy and safe
Mark
Mark Cortright
www.liscomhillpottery.com

#5 Pres

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Posted 06 May 2012 - 09:53 AM

Put a small amount of the test clay (a small chunk ) in any high fire bisqued piece-It can be a pinch pot to a cup or bowl or a spoonrest-just something to catch the liquid mass of the melted low fire clay piece so it does not spill onto kiln shelves. Fire to cone 6 or cone 10 whatever temp you are working at. If piece is still intact and not melted its high fire if a puddle its low fire.
Test is easy and safe
Mark


You could go a little further and put a measured line a clay slab, and lay it in a bowl where it is supported only on the ends. Three things it would tell you-if it slumps, it is probably a couple of cones off, if it puddles, way off, if it slumps or does not you can measure the line and find out the shrinkage. One final test would be to check for absorption. You may not identify the clay, but you could pretty well classify it.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/





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