MNP

Mother Nature's Porcelain, MNP, is a pure mined sedimentary clay called "3B" that Plainsman Clays mines in a quarry in south western Saskatchewan. It is a natural mix equivalent to about a 35:65 mix of ball clay and feldspar (with some iron staining) and is fine grained naturally. It fires porcelain density at cone 6 (although not white burning).

Plainsman Clays does NOT make this as a body. But you can make your own from the raw lump material or 42 mesh powder. Traditional porcelains, like P300 and M370, are carbon-intensive, made from highly processed industrial minerals transported across North America and even over oceans. Making your own MNP is the ultimate low-carbon way to have a porcelainous body. Of course, you must live near to the Plainsman plant to be able to buy the raw material and have a little equipment to make it (see below).

A 10kg lump of B clay at the quarry (from the center section of the seam). It is quite damp and amazingly dense and heavy. It is layered, somewhat like the rings on a tree, the lines run horizontally in the clay bed. In the lab its splits apart in layers (revealing carbon stringers of Cretaceous plant life).

The finer you are able to sieve the 3B crude clay the more plastic and smoother it will be. 95% should pass a 200 sieve and 90% a 325. Plasticity can be augmented with a small bentonite addition (e.g. 1-3%).

To process it slurry up the powder, sieve it, and dewater it on the plaster surface until the desired stiffness is achieved. Although it is possible to hand-sieve the material for sizes up to about 80 mesh, a sieve shaker is needed for finer sizes (100-325 mesh). At 100 mesh is practical to make most things. At 80 mesh some fine specks may show through glazes.

On the wheel this feels like porcelain - but throws better, it is super plastic but not at all sticky. But unlike porcelains made from commercial minerals, MNP has the drying properties of a stoneware (because of its high dry strength). Mother Nature has done a superb job of mixing the silica, feldspar and clay!

MNP is the best choice for making dark-colored porcelains, it requires less stain (e.g. black, brown, blue).

MNP fired test bars from cone 8 (top) to cone 4 (bottom). The bars on the left are the standard 42 mesh pugged material we suppy. The ones on the right we made using a slurry up process, sieved to 325 mesh.

200 mesh MNP fires to zero porosity at cone 6. Add 5-10% feldspar or nepheline syenite if maturity is needed at cone 4-5.

MNP with 6% 6666 stain (right) vs. Coffee Clay at cone 5

MNP has enough natural quartz so that almost any glaze that fits our other bodies will fit this.

These are the properties of the 42 mesh material. The finer you screen it the more vitreous it will fire.

 Drying Shrinkage: 6.5%
 Dry Strength: n/a
 Drying Factor: C120
 Dry Density: n/a

Sieve Analysis (Tyler mesh):

   +65: ~0.5
 65-100: ~2.5
 100-150: ~2.0

Fired Shrinkage:

 Cone 4: 6.0
  Cone 5: 6.5
  Cone 6: 6.5
  Cone 7: 6.5

Fired Absorption:

 Cone 4: 1.5
  Cone 5: 1.0
  Cone 6: 0.5
  Cone 7: 0