Determination of Shape of Kaolin Pigment Particles

Abstract

Abstract Characterization of platiness of kaolin pigments was derived from the divergence of measurements of their particle size distribution by two different techniques: sedimentation and light scattering. A numerical shape factor, which is related to the ratio of kaolin particle face diameter to its thickness, can be calculated to provide a quantitative measure of such platiness. Two sets of kaolin pigments were prepared from a Middle Georgia kaolin: delaminated and non-delaminated. Shape factors of delaminated samples were higher than those of non-delaminated ones. Maximum platiness was found between equivalent volume diameters of 1·0 and 2·0 μm. Examples are presented where properties of coated paper are correlated with the size and shape of kaolin pigments.