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Mulcoa 70 Mullite

Alternate Names: Mulcoa 70 Calcined Grog, Mulcoa 70 Calcined Mullite

Oxide Analysis Formula
Fe2O3 1.20% 0.01
TiO2 2.80% 0.05
SiO2 26.80% 0.66
Al2O3 68.80% 1.00
Oxide Weight 147.66
Formula Weight 147.66


This material is produced from calcined mullite that is precisely sized through a series of screens and blended to obtain a series of coarse to fine sizes. During screening the grains are de-dusted. The product is used mainly for stucco and investment casting, in ceramics its main application is as a low expansion grog for bodies.

Mulcoa 47 and Mulcoa 60 are alternate products, these numbers refer to the approximate alumina content. Mulcoa 70 is thus the highest in alumina and therefore highest in mullite mineral (87%) and the lowest in glass. Mulcoa 47 is 65% mullite and 20% glass and 15% cristobalite (the others have no cristobalite).
Mulcoa 70 is the most refractory, Mulcoa 60 is 37 PCE and Mulcoa 47 is 35 PCE. Mulcoa 47 has a reheat change of 0.8% at 2800F and 3.1% at 2910F, Mulcoa 60 is zero for both.

Various grades for each are available in the following U.S.S. Sieve Mesh sizes:
10x18, 14x28, 16x30, 22S, 35S, 50S, 60S, 20x50, 35x80, 50x100, 60x200, 300S, 200 IC-C, 325 IC-C

Related Information


Minerals Mullite
Materials Mullite
Materials Mulcoa 60 Calcine Grog
Materials Mulcoa 47 Calcine Grog
Typecodes Aggregate
Granular materials intended to impart raw and fired structural strength or thermal expansion properties to bodies or deliver special speckling effects in glazes.
Glossary Calcination
Calcining is simply firing a ceramic material to create a powder of new physical properties. Often it is done to kill the plasticity or burn away the hydrates, carbonates, sulfates of a clay or refractory material.
Glossary Firebrick
In the ceramic industry, these are the bricks used to build kilns. This term grows out of their ability to withstand high temperatures that would melt or deform structural bricks.


Apparent Porosity3.5%
Bulk Density g/cc (Packed)2.88
Pyrometric Cone Equivalent39
Reheat Change0% at 2800F, 0% at 2910F

By Tony Hansen

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