M
A ball clay, and the plasticiser in a throwing body or a casting slip · More than half of it finer than half a micrometre · High dry strength, so green work handles without breaking · Low in iron and titania for a ball clay
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M-23 is a ball clay: a sedimentary clay whose particles are fine enough to make a body plastic and strong while it is still raw. Its iron and titania are low for a ball clay, low enough to carry the plasticity of a white body.
M-23 is the plasticiser in throwing bodies, casting slips and porcelains, and it suspends and binds a glaze slurry. More than half of it is finer than half a micrometre. While the body is wet, water films between the plate-shaped particles let them move past one another without losing contact; as the water goes, they are drawn close and hold. Fineness is most of why a ball clay is plastic and strong raw, though mica and carbonaceous matter take a share. That fineness is also why it takes a great deal of water to work and shrinks as the water leaves, so a body carries a measured amount of it rather than resting on it alone.
