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