China Clay for Paint Industry:
Kaolin just refers to the white earthy pigment of silica and alumina. All the white clays for use in paint must contain Silica and alumina combined with water. The texture of the clay varies according to this composition. China clays with the closest match to the below chemical composition are the best to be used in paint industry.
Silica (SiO2) - 47 per cent
Alumina (Al2O3) - 39 per cent
Water - 14 per cent
Free Moisture, Magnesia, Potash and Iron – 1 per cent
The colour maker will however prefer the pigment that is entirely free of iron oxide. Domestic kaolin will vary somewhat from this analysis, generally consisting of more silica and showing appreciable fractions of one per cent of iron oxide and lime. These types are still largely used in many special paints, where light weight per gallon is desirable.
To be contd…
