ExCal W 7 Calcium carbonate Excalibar Minerals Extenders / Fillers >> Calcium Carbonate, ground ADHESIVE SEALANT ExCAL W Calcium Carbonate products are processed from a high purity ore, to exacting specifications at our Houston, Texas plant. The grades are processes for use in paints, plastics and other applications where color and particle size are of importance. High purity, bright white calcium carbonate processed for use in rubber, plastics, paints and coatings. Calcium carbonate. Possesses bright white color and high purity. Used in adhesives and sealants. Suits for applications where color and particle size are of importance.