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Kaopaque 20 Kaolin

Alternate Names: Kaopaque, Kaopaque Kaolin

Oxide Analysis Formula
CaO 0.21% 0.01
K2O 0.08% 0.00
MgO 0.03% 0.00
Na2O 0.03% 0.00
TiO2 0.66% 0.02
Al2O3 39.30% 1.00
SiO2 45.20% 1.95
Fe2O3 0.32% 0.01
Oxide Weight 222.76
Formula Weight 253.14


A white firing delaminated material of low plasticity. Kaopaque 20 and 10 are non-predispersed from a water-fractionated feed for a controlled particle size and shape (very large plate-like). It is refined from Geogia deposits.

Kaopaque 10S is the pre-dispersed version and is supplied as a lightly pulverized spray-dried powder and as a slurry. The large plate-like particles of Kaopaque 10 have a thickness of 0.2 to 0.4 microns and a diameter of 2 to 10 microns.

Kaopaque is useful in casting porcelains. It fires white compared to other North American kaolins, but others available internationally are whiter (e.g. New Zealand kaolin). Kaolins of higher iron content, like Opticast, also work well for slip casting and cost much less.

Kaopaque 20 has very high fired shrinkage (from 10-12% from cone 8-10), happening inspite of the fact that it is very refractory (15% porosity at cone 8, 10% at cone 10).

Related Information


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

By Tony Hansen

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