optiKast Kaolin

Alternate Names: OptiCast

Description: Large Particle Size Kaolin

Oxide	Analysis	Formula
SiO2	45.20%	1.98
Al2O3	38.70%	1.00
Fe2O3	0.50%	0.01
TiO2	1.60%	0.05
CaO	0.10%	-
K2O	0.10%	-
Na2O	0.10%	-
LOI	13.60%	n/a
C	0.03%	n/a
SO3	0.04%	n/a
Oxide Weight		227.46
Formula Weight		263.47

Notes

optiKast is a coarse-grained kaolin used primarily in ceramic casting applications. It has a very fast cast and exceptional deflocculation characteristics. Thus optiKasT is preferred in pressure casting systems.

Velvacast kaolin is no longer available, this is the recommended substitute. One concern with Velvacast was its dark fired color (compared to other common plastic kaolins). Opticast has higher iron and TiO2 contents, this could impact translucency in porcelains, for example. Thus you may need to fire tests and adjust other materials in the recipe if needed. We have done fired shrinkage, porosity, dry performance and plasticity comparison tests between these two materials Oct 2011 and they do appear very similar, Opticast is a little more plastic and does not appear to fire darker at cone 8 and 10.

Related Information

Links

Typecodes	Kaolin Pure clay mineral, there are many brand names of varying purity and iron content.
Materials	Velvacast Kaolin

Data

% < 0.5 microns	18.0
% < 5 microns	74.0
% Passing 325 Mesh Wet	94.0
Modulus of Rupture - Dry	225 psi (50/50 clay/silica)
Surface Area (m2/gm)	11.0
% < 20 microns	94.0
% < 10 microns	85.0
% < 2 microns	55.0
% < 1 micron	37.0
pH for dry powder	5.7

By Tony Hansen
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