Absorption and scattering of light by pigment particles in solar-absorbingpaints

The optical properties of black-pigmented solar absorbing paint were analyz ed phenomenologically by use of the Kubelka-Munk theory, including correcti on for reflection on front and rear surfaces. The effective absorption and scattering coefficients and the efficiency curves far absorption and scatte ring were calculated for coatings with different pigment-to-volume concentr ation ratios. The dependence of absorption and scattering efficiency on the pigment-to-volume concentration ratio was analyzed by reference to theoret ical data in the literature. It was concluded that, during drying and curin g of coatings, spherical primary pigment particles most likely collect in e longated groups oriented perpendicularly to the coating surface. Formation of such groups helps in understanding the independent measurements of solar absorptance. (C) 2000 Optical Society of America.