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Alternate Names: Plainsman FireRed

Oxide Analysis Formula
BaO 0.30% 0.01
CaO 0.50% 0.06
K2O 1.10% 0.08
MgO 0.60% 0.10
Na2O 0.10% 0.01
TiO2 0.90% 0.07
Al2O3 15.40% 1.00
P2O5 0.20% 0.01
SiO2 66.30% 7.31
Fe2O3 6.90% 0.29
MnO 0.10% 0.01
Oxide Weight 612.00
Formula Weight 662.34


A natural, high iron, high temperature stoneware clay blend of a refractory low plastic red clay, a medium temperature medium plastic red clay and a bentonitic ball clay. Fire-Red has medium plasticity and is thus a plasticity nuetral additive to clay bodies. It is slightly sandy and by itself is a deep, solid red at cone 10R with speckle. It is stable to cone 12+. This material is a better choice for impart red color to medium and high temperature bodies than typical low fire red clays (the latter tend to flux to brown rather than red colors even in bodies with low feldspar).

This material is a possible alternative to Newman red fireclay with caveats.
-This material is more plastic (thus ball clay or bentonite in the recipe can be reduced to compensate)
-Fire-Red is a little more vitreous (thus feldspar can be reduced).
-Fire-Red has a much coarser particle size distribution so homogeneous red burning bodies will look less so and they will have a much more toothy feel.
-Fire-Red has less staining power, you may need to augment it with iron oxide.

Fired Temperature, Cone 6 7 8 9 10 11 10R
Fired Shrinkage: 3.2% 3.4% 3.6% 3.6% 3.7% n/a n/a
Absorption: 8.2% 8.0% 7.8% 7.5% 7.1% n/a n/a
Fired Strength:
(lbs/ square inch) 3800 4200 4300 4300 4300

Sieve Analysis Wet Washed
(Root of 2 series) +35 +48 +65 +100 +150# +200 +325
0.1% 0.5% 2.5% 5.0% 6.0% 11.0% 11.0%

Texture: Sl. tooth
Plastic Index (1-10): 5
Green Strength (lbs/sqaure inch): 800
Dry shrinkage: 5.5
Dried density: 2.06
PCE: 16.5

Related Information

Fire-Red fired to cone 10R with Ravenscrag Slip as an inner glaze.

This can fire almost black on reduction. However, as a pure material, it is prone to dunting as it is high in larger quartz particles.

Fire-Red and Restone fired test bars

Plainsman Fire-Red (left) fired at cone 8,9,10,11 and 10R and Redstone (right) fired at cone 4,5,6,7,8.

Varying sizes of iron speckle in a high-iron reduction stoneware clay

Cone 10R firing of Plainsman Fire-Red (left), St. Rose Red 42 mesh (center) and St. Rose Red 10 mesh (right). The 10 mesh material produces a reduction speckle and deep red color that is very unique.


URLs https://plainsmanclays.com/data/index.php?product=12906
Fire-Red Data Sheet
Materials Redstone
Materials Saint Rose Red
Materials A1 Ball Clay
Materials M2 Red Stoneware
Materials Newman Red Clay
Materials Plainsman Red Fireclay
Materials Calvert Clay
Typecodes Fireclay
Fireclays are non-kaolin non-ball clay materials similar to stoneware clays but lacking fluxing oxides. Many fireclays have a PCE of 28 or more.
Typecodes Clay Other
Clays that are not kaolins, ball clays or bentonites. For example, stoneware clays are mixtures of all of the above plus quartz, feldspar, mica and other minerals. There are also many clays that have high plasticity like bentonite but are much different mineralogically.
Suppliers Plainsman Clays


Drying Shrinkage6.0-7.0
Firing ShrinkageCone 4: 3.0-4.0% Cone 6: 3.5-4.5 Cone 8: 4.0-5.0 Cone 10: 4.5-5.5 Cone 10R: 3.0-4.0
Frit Softening PointPCE 17
Sieve Analysis Dry+48 mesh: 0.5-1.0% 48-65: 2.0-4.0 65-100: 3.0-5.0 100-150: 4.0-6.0 150-200: 5.0-7.0 200-325:
Water absorptionCone 4: 9.0-11.0% Cone 6: 7.5-9.5 Cone 8: 6.0-8.0 Cone 10: 5.0-7.0 Cone 10R: 2.0-3.0

By Tony Hansen

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