Velvacast Kaolin

Alternate Names: Velva Cast

Description: Large Particle Size Kaolin

Oxide	Analysis	Formula
CaO	0.26%	0.01
MgO	0.18%	0.01
TiO2	1.10%	0.04
Al2O3	38.91%	1.00
SiO2	45.49%	1.98
Fe2O3	0.37%	0.01
LOI	13.70%	n/a
Oxide Weight		226.26
Formula Weight		262.17

Notes

A large particle size kaolin intended for casting slips. It is low in plasticity and fires a darker color than what the reported iron would indicate? Combining some of this material with other kaolins of finer particle size in casting recipes will reduce casting times because of the greater permeability of the slip.

Kaolins of this type are also valuable for use in tuning the shrinkage and plasticity of slips or engobe applied to wet, leather hard or dry ware (as opposed to using more expensive calcined kaolins). Because their shrinkage is very low, they can be substituted for part of the regular kaolin and there will be minimal impact on the fired properties.

Related Information

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Materials	Kaolin The purest of all clays in nature. Kaolins are used in porcelains and stonewares to impart whiteness, in glazes to supply Al2O3 and to suspend slurries.
Materials	optiKast Kaolin
Typecodes	Kaolin Pure clay mineral, there are many brand names of varying purity and iron content.

Data

Pyrometric Cone Equivalent	34-36

By Tony Hansen
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