Abstract: A method for calibrating an apparatus for measuring shape factor is provided, wherein the method comprises determining aspect ratios for each of a plurality of kaolin samples and measuring the shape factors of each of the plurality of kaolin samples using the apparatus, wherein each of the kaolin samples includes potassium oxide in an amount less than about 0.1% by weight of each of the kaolin samples. The method further includes calibrating the apparatus based on a correlation between the aspect ratios and the shape factors.

Abstract: An inorganic particulate suspension may include a first kaolin having a shape factor of at least about 70, and a second kaolin having a shape factor less than or equal to about 20. The first kaolin and the second kaolin form a kaolin composition, which may have a content ratio of the first kaolin to the second kaolin ranging from about 90:10 to about 50:50. An inorganic particulate suspension may include a kaolin composition having a shape factor ranging from about 55 to about 75, wherein at least about 70% to about 90% by weight of the particles of the kaolin composition have an equivalent spherical diameter less than 2 microns. The suspension may have a Hercules viscosity ranging from about 600 rpm to about 700 rpm at 18.0 dyne using an “A” bob, and the suspension may have a solids content ranging from about 55% to about 75% solids.

Abstract: A pigment composition may include an inorganic particulate material, a multivalent metal salt, and a non ionic dispersant. A substrate may be coated with an aqueous coating composition including the pigment composition. The substrate may be a paper product.

Abstract: A method for calibrating an apparatus for measuring shape factor is provided, wherein the method comprises determining aspect ratios for each of a plurality of kaolin samples and measuring the shape factors of each of the plurality of kaolin samples using the apparatus, wherein each of the kaolin samples includes potassium oxide in an amount less than about 0.1% by weight of each of the kaolin samples. The method further includes calibrating the apparatus based on a correlation between the aspect ratios and the shape factors.

Abstract: The present invention relates to a kaolin composition having improved physical properties, for example, for use in the production of paper products. The composition can comprise kaolin having a shape factor of at least about 20. The kaolin can have a particle size distribution such that at least about 94% by weight of the kaolin can have an esd of less than about 2 ?m and/or at least about 80% by weight of the kaolin can have an esd of less than 1 ?m. The amount of the kaolin having an esd of less than about 0.25 ?m can range from about 25% to about 60% by weight. The Hercules viscosity of the kaolin product is less than 4000 rpm at 18 dynes at 63% solids and less than 1500 rpm at 18 dynes at 69% solids when measured using the “A” bob. The present invention also relates to an improved method for making the kaolin product from sedimentary kaolin.