STONEWARE refers to natural mixtures of kaolinitic clays, fine

silica, feldspathic mincrals and iron that vitrify at cone 8 or higher to
a grey, porcelaneous body of a very low absorption. They are in fact
natural, impure porcelains. Potters unable to obtain stoneware clay
often produce impure porcelains under the heading of "stoneware"; such
artificial stonewares are sound but they are generally of limited
workability and texture.

The best stoneware bodies are made from a mixture of clays ranging
from ball clay types to kaolinized sands, this permits control of
workability and drying characteristics. True stoneware bodies range
in colour from near white to light brown but a point in darlmess of
body is reached where we have to consider them no longer stoneware.
Our H-32 comes very near to this point. Natural stoneware bodies of

poor quality

feldspar so reduces the plasticity that it is necessary to add at least
10% ball clay at which point the body starts to lose some of its

stoneware quality.

When both good icity and superior drying properties are essential
as for handstand very large pieces "ft necessary to formu-
late a body emp . Simply adding grog to an existing body
will n unless was entirely too plastic to start with. To
gain the desired result all or most of the Sandy TEAChion SHON be re-
placed by from 20% to 50% of the batch weight of grog, depending

upon the plasticity of the basic clay. The grog used should be stone-
ware if at all possible so that at the height of the firing it will vitrify
along with the rest of the body, adding to the final strength rather than
reducing it as does fireclay grog. To be able to use the greatest per-
centage of grog it should range in size all the way from 100 mesh to
20 or 16 mesh.

Lowering the maturing temperature of a firecla the addition of
low-fire clay does not resu a stoneware body, it has no real

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