Whiteness of kaolin
Whiteness is one of the main parameters of kaolin processing performance, and kaolin with high purity is white. The whiteness of kaolin is divided into natural whiteness and whiteness after calcination. For ceramic materials, the degree of whiteness is more important after calcination. The higher the calcination whiteness, the better the quality. The ceramic technology stipulates that drying 105 degrees is the classification standard of natural whiteness and calcined at 1300 C is the grading standard of calcination whiteness. Whiteness can be measured by a whiteness meter. A whiteness meter is a device for measuring the reflectivity of 3800 to 7000&Aring (i.e., 1, =0.1 nm) wavelength. In the whiteness meter, the reflectance of the sample to be measured is compared with the standard sample (such as BaSO4, MgO, etc.), that is, the whiteness value (such as whiteness 90 is equivalent to 90% of the standard sample reflectivity).