What is the effect of using different crushed rock when making clay?

by Flip
(Chewelah WA)

Question: I was making clay that I dug up on my uncles farm but I mixed it too wet. The problem is that it is winter here and I did not have any easy access to dry sand. I had some granite with hornblende in it and I crushed it up and screened it and added it to my clay mix. It worked like sand and the clay came out okay.

I was wondering if I crushed up other kinds of rock like green serpentine or black marble or quartz and used that as sand or just an additive to clay, just what would be the result?

Answer: I haven't used any of those additives, so I can't say for sure. I've heard that quartz expands a lot in the firing and therefore wouldn't be the best choice.

The best way to find out which one would work the best is to do small samples and test fire them. Then you can compare the shrinkage and firing results and use the one that works the best.

Those are the joys and frustrations of working with homemade clay!

Hope that helps,
Steve

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Jun 05, 2012
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clay too wet
by: Jan

If you make clay that is too wet and you don't want to add anything else. Turn the clay into a clean wheelbarrel in about 3 inch thickness. Then put the wheel barrel in the sun. Move the wheel barrel around the yard, catching the best the sun can offer. You turn the clay in the wheel barrel with a 6 inch paint scrapper, the same one I use on my wedging board.
After the clay feels dry enough turn it in small amounts onto your wedging table and wedge. If your clay is like mine it will still have a lot of moisture and the wedging will help remove it. The wedging will also make the clay one consistancy.
Hope this helps.

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