Wollastonite (Calcium metasilicate)

General-purpose wollastonite (calcium metasilicate) is a needle-shaped functional extender pigment suitable for water-based latex paints, inorganic coatings, powder coatings, and various specialty coatings. It significantly enhances film hardness, scrub resistance, and crack resistance, while providing alkaline buffering and whitening/covering effects to improve the weather and aging resistance of exterior walls. For primer, anti-corrosion, and fireproof coating systems, 800-1250 mesh grades (D50: 8-15μm) are recommended; for topcoats and high-gloss latex paints, ultra-fine 1250-2500 mesh grades (D50≤5μm) are preferred. The typical addition level in architectural latex paints is 5%-15%; overuse should be avoided to prevent loss of gloss. It is advised to add this material during the grinding and dispersion stage together with ground calcium carbonate, talc, and titanium dioxide.