• Materials for Ceramics

Newman Red Clay

Alternate Names: Newman Fireclay, Newman Slip

Description: High temperature red burning low plastic stoneware

Notes

In 2003, this material became unavailable. There were problems with consistency and a lack of compatibility with light colored materials also produced at Gladding, McBean & Co. However, as of Mar 2004, it was again available. The reintroduction was accompanied by a new data sheet (on which the chemical analysis numbers only add up to 92.8)? In addition, the material was more expensive and more coarsely ground (some 30 mesh grit), so some companies began using substitutes. In March 2006 is was again unavailable.

Newman was a red-burning, low-plasticity, low dry strength fireclay useful in both plastic and casting bodies to impart red color. It had powerful staining abilities (beyond what its percentage of iron suggested). For example, even if diluted to 50% in a recipe, the body could still fire bright red in oxidation. Newman clay had a very fine particle size coupled with some large impurity particles in the plus 50 and even plus 30 mesh range. The crude material color was bright orange. Not surprisingly, bodies containing it complemented it with ball clay and feldspar.

Coming up with an economical substitute for this material is a tricky task both because of its unique combination of properties. There is no other commonly available smooth refractory red-burning clay material in North America. Thus, some have suggested substituting various low and mid-fire red clays to impart color to clay bodies (i.e. Carbondale Red, Redart). However, this is not practical since these materials flux the body, producing a more vitreous and browner fired result. Even if feldspar is removed from the body to compensate the red coloration is still most often compromised to brown. Some have suggested mixes of fireclays mined in the same area (i.e. IMCO 400, 800, Lincoln Fireclay). However, these are not nearly refractory enough either (they are not real fireclays despite the naming) and they have far less iron. Two other possible alternatives are refractory and red burning: Plainsman Firered, Plainsman St. Rose Red. These are not as fine-grained as Newman and contain iron speckle or other impurities; testing would be needed to confirm their suitability. Newman has another curious property: a high firing shrinkage despite its refractory nature.

A mix of materials that has proven quite similar to the character of the color, the maturity, the smoothness and plasticity is L3179H: Imco 400 Fireclay - 67, Silica - 27, Iron Oxide Red: 3, Iron Oxide Yellow: 3. The mix of red and yellow iron also duplicate the raw color (below there is another option).

Jan 2003 Analysis:
SiO₂ 59.2
Al₂O₃ 21.5
Fe₂O₃ 7.71
CaO 0.05
MgO 0.22
Na₂O 0.22
K₂O 0.87
TiO2 0.98
LOI 7.3

Considering this analysis and the appearance and fired properties of the fired test bars you might find that a viable substitute could simply be 92% kaolin and 8% iron oxide.

Related Information

Newman Red clay powder

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Newman Red clay fired test bars at a range of temperatures

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New is a high temperature red burning fireclay. These fired test bars show how high the iron content is, turning it bright red at all temperatures, even cone 10R (top bar). Other bars are cone 11, 10, 9 and 8 oxidation (top to bottom). Notice it does have some soluble salts that darken the color in reduction.

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