l Patent No. U.S. 6,531,223 B1
The Sherwin-Williams Company has been granted a patent for a water-based coating composition comprising at least one tannin blocking latex resin; microspheres having a maximum pigment loading of at least 50%, the microspheres being selected from the group consisting of expanded acrylonitrile/vinylidene chloride copolymer particles, sodium potassium aluminum silicate particles, polyvinylidene chloride copolymer particles coated with calcium carbonate, ceramic particles, glass particles and polyethylene particles; and a reactive pigment. The coating composition has a PVC of 25-65% and a NVV of 30-50%, and wherein a single coat of the coating composition has exterior durability as measured by QUV testing and indicated by a DE of less than three, and tannin blocking as measured on a redwood substrate and indicated by at least a 30% improvement in the y-reflectance.