Product Description
Ultramarine pigments are sodium aluminum silicates with small sulfur containing anions (e.g., S3 and/or S2) bound as chromospheres in the interstices of the crystal lattice to equalize the charge. Depending on composition, blue, red, green or violet pigments can be obtained, the hue being altered by varying the amount of silica. Ultramarine pigments have a high heat resistance but their universal use in paint is limited on account of their poor hiding power and limited weather resistance. Special types of ultramarine pigments are coated with silica to reduce ultramarine's susceptibility to acid and improve its weather resistance.