M390 Plainsman Clay

*Priced per 20kg box.

M390 fires dark red and is the material of choice for dark burning functional ware. It contains more of our native Redstone material than any other body. It is one of several bodies that we process to 100 mesh particle size and is intended to produce ware with a clean, unblemished glaze surface.

M390 is very similar in composition to M350 and shares the very fine natural smooth character. It is however more plastic. Its darker color tends to limit it to specialized glaze effects. M390 contains 5 different clays, each of which is quite balanced on its own.

Process Properties
M390 has high plasticity and feels smooth (possible very slight tooth). It generates significant slip during throwing if too soft. Care and attention during drying are a must, especially with larger pieces, flat plates, shallow bowls, and sculptural ware. Put the focus is on evenness of drying rather than speed. If sections of a piece dry faster, then either slow these sections down or slow down the entire piece.

Firing
M390 is a fairly high iron body and thus burns red to brown as it matures. At cone 3-4 it is a very warm toasty red. The red intensifies as it approaches cone 6 and turns brown by cone 7. We maintain the porosity at about 2.0% at cone 6 to hold onto the red color. We regard it as over-fired at cone 7 (although you might have success) but at cone 8 it will definitely be unstable (tending to bloat and warp). This instability occurs even though it has not reached zero porosity.

Transparent glazes will darken the color of the underlying body. If you fire to cone 7 keep in mind that accidental over firing could take it into the warping or bloating territory of cone 8. If you fire to cone 4, be aware that porosity is too high (and strength likely too low) for practical functional ware. Cone 6 is the best compromise of color, stability and strength.