Are white coatings still effective as they age?
Two values of reflectivity are often quoted to represent the performance of new coatings and three-year-old white coatings, respectively. Generally, a small decrease in reflectivity occurs, depending on several factors. Wind-blown dirt and dust can decrease the reflectivity of white coatings, depending on the age of the coating and regional characteristics. The Sacramento Municipal Utility Division (SMUD) annually publishes data on the reflectivity of hundreds of different white coating products, which are rated for initial reflectivity and reflectivity after three years of weathering.
