|Monthly Tech-Tip |
These are the same clay body. But 0.35% barium was added to the one on the left. Notice that the soluble salts concentrate on the edges of contours even developing enough glass to cause plucking. But they also darken and vitrify the whole surface of the bare clay.
In ceramics, certain compounds in clays and glazes can dissolve into the water, then on drying these are left on the surface.