I had a bit of a run- in with some clay today. Because it was in between quarters, I either have to pair up with someone and make some clay with the machine, or pick up the scraps left over from last quarter. Fortunately, there was a big 200 lb scrap of clay in the independent studies room.
I grab 20 fist sized chunks of it and wedge/slam them together. I set everything up at the wheel… everything is awsome… and i throw pots… 2o of them… so i can perfect my throwing skills/make some test tiles/make some presents for friends.
Well I note how unusually dry the clay was, since it had been sitting around all quarter, and during my first few tries at it, the pots split vertically along the sides. Yup its too dry. So I spend the rest of the evening turning the remaining balls into coils.
Now note what you can and can’t do with clay (well at least in my experience). I just want to save you all from tragedy.
Wet Plastic
This stuff is like dense whip cream in your hands, and quite sticky.
Go ahead and try to wedge it, it’ll stick to anything if its not a wedging table (that’s made up of dry plaster). Plaster and clay hate each other. Clay will slide off of plaster as if it were wax. Plaster will blow up if you fire it.
Go ahead and try to build with it. You’ll get sagging. Unless you want unsightly bulges and cellulite in your statuary, don’t build with wet plastic.
Throw with it on a wheel. It will do whatever you want it to, its a push over. It centers quickly, and it doesn’t mind stretching.
Dry Plastic Clay
This stuff can still bend, but it will crack on the edges a little. It doesn’t feel sticky anymore, but it’s wet to touch.
Go ahead and try to throw it. First of all it’ll split on the sides if you try to stretch it. Wedging it will make it crumble a bit.
This stuff is great for modeling. So what if it cracks a little? Just smooth it out with slip and rubbing.
Wet Leather Hard
This stuff is slightly darker in appearance than plastic clay. You can’t bend it very much, it’ll crumble too fast. This is the last chance you have to score and slip it to other clay. When you score it, it will still form grooves, and a couple of chunks will fall off.
Dry Leather Hard
It’s hard to tell apart from wetter leather hard clay. The only notable difference is that when you scratch it, chunks fall off instead of forming soft grooves. Basically all you can do now is carve it. I like carving it at this point the best. Burnishing works pretty nice here too.
Bone Dry
Its much lighter than either plastic or leather hard states. If you scratch it or carve it, powder falls off. Be very careful here. Carving here is much slower, and chances are, if you push too hard, a big piece will crack and fall off. This is where you want to apply glazes to the sculpture.
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