Burnt kaolin - general information

What is kaolin?

Kaolin is unstrengthened sedimentary rock mainly of Tertiary origin, with a high content of clay mineral kaolinite. Kaolin had been forming by weathering or by hydrothermal decomposition of rocks rich in potassium feldspar.

They have low content of coloring matter.

Content of clayey material (particle size below 0.002 mm) in the kaolin is between 45-65 %. Al2O3 content (in the annealed state) is between 37-42 %.

Thru the firing process we obtain from kaolin the high-quality ceramic grog typical for his white color and excellent refractory properties.

The material is then crushed or ground in a drum mill (high aluminum lining and grinding bodies) and due to its stability, purity and specific thermal expansion coefficient is used as a filler material to ceramics and glazes. 

“ČLUZ” kaolin:

  • White grog with water absorption in the range of 6-18%
  • 3 kinds of burnt kaolin with a different thermal expansion coefficient


  • ground to grain size of 1 mm to mass for production of electro porcelain and Sanitary ceramic
  • finely ground to 45 µm addition to glazes