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M-4 Fireclay

Oxide Analysis Formula
CaO 0.11% 0.01
K2O 1.18% 0.05
MgO 0.40% 0.04
Na2O 0.57% 0.04
TiO2 1.07% 0.06
Al2O3 24.61% 1.00
SiO2 59.20% 4.08
Fe2O3 1.86% 0.05
Oxide Weight 368.87
Formula Weight 405.80


From Industrial Minerals Ione, California clay deposit. Roller milled, air floated. Has excellent adhesiveness, low abrasiveness and free flowing qualities. Similar to Lincoln Fireclay.

It is used for insecticide and its data sheet does not highlight ceramic qualities.

We measured porosity of 3% at cone 10R, 3% at cone 8 and fired shrinkage of 8.5% at cone 10R, 9% at cone 10 oxidation, 8.5% at cone 8. Fired bars show a straw color at cone 5 with a shift to greyish at cone 8. The color is stable cone 8-11 as a variegated green-grey of slightly increasing density. At 10R the scum (from soluble salts) turns it variegated light and dark brown. At cone 11 and 10R it is still not vitrified looking. Drying shrinkage is about 5.5%.

Their data sheet:
Moisture: 1.9%
Soluble Sulfates: .15%
Minus 325 mesh: 96%
pH: 5.75
Density, lbs per cubic foot: 26.1
Oil Absorption (spatula rub-out method): 40.4
Bulk Density (lbs per cubic foot): 26.1

Related Information

M-4 Fireclay fired bars

Cone 10R top, cone 11 oxidation downward below that.


Materials Imco 400 Fireclay
Materials Fireclay
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.
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.

By Tony Hansen

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