Now that the clay harvesting is over, and I have tested each of the five clays individually, and found none of them to be great on its own (except for clay number one, of which I have only a couple of buckets) I have started to test different mixes of the clays. The first tests are clays, 2 and 3 mixed at 50% each. When this mix was cast it held up well. At cone 05 it is a nice pinkish color and held its form well. When it was thrown and fired to the same temperature, it had the white minerals floating to the surface and then undermining the integrity of the pot over time. The same thing happened at higher temperatures, like cone 5, when thrown the minerals came to the surface over time and undermined the pot again, on the cast piece, that didn’t happen and it is solid. At cone 5 the clay goes green. There has to be something about the throwing that causes the minerals to migrate. The spinning of the molecules? The taking the clay to a dryer, plastic state to throw it? Using less water than when it is cast as liquid clay? Does the plaster of the mold pull the problem minerals out of the clay? All very mysterious to a chemistry cave man.