How do you clean and prepare fresh dug clay for sculpting? It has many fine rocks and dirt in it?

Question

We have 10 lbs of fresh Maine coast clay and I forget from my many art classes how to clean the grit before we use it. It involves soaking it in water. I'm just not sure what for and how does this remove the rocks/sand?

Answer 1

I have never actually used fresh dug up clay, but I imagine that you would want to soak it in water and break it down to a slip. From there I would strain the slip into a clean bucket. This would catch all of the debris. Then you would have to allow the clay to settle for awhile so that you could carefully pour out the excess water from the top. Then you would have to wedge it on a plaster bat/slab to get it back to sculpting conditions. Or you can use it in the slip form if you want to do a pour mold.

Answer 2

I'll agree with the first one, mostly - dry the clay (this will take several days), grind it up (once I used a piece of a 2x4, anything works), and put it through a sieve. Depending on what kind of clay you have or want you should probably take it down to an 80/0 mesh, but I've done 30/0 and it's just been a bit rougher to work with - i.e. it's like sandpaper for throwing.

I suppose you could make a slurry and sieve that, but I'm not sure if it'd gum up the mesh too much. Seems like it might be easier, though.

Also, if you don't know about all the different things you can add to make the clay completely useable (bentonite, kaolin, fire clay, etc) I'd do a little research on that and play around with it a bit.

Answer 3

You need to let it dry, and then crush it. While crushing it you can remove any large pieces of debris or stones. Then mix it thoroughly with clean water (rain water is best) and allow it to settle. Remove the clay from the container. If you can do this in one piece (not easy unless you slit the container) you should be able to cut off the section with the sand and gravel in it off.

Don't forget you need to work the clay thoroughly before using it, other wise you may get air bubbles.