Optimization of the diffuse reflectance of pigmented coatings taking into account multiple scattering

The optical properties of particulate coatings consisting of homogeneous rutile or anatase pigments randomly distributed through a polymeric binder are considered in the solar spectral range. The sizes of the pigments leading to the highest values of the effective scattering coefficients per unit length are established from a multiple scattering approach. Also, taken into account are boundary reflections of the diffuse radiation at the interfaces of the particulate coatings. Optimizations of the solar reflectance of pigmented coatings are also carried out. Fairly good agreement is found when comparing to solar reflectance values obtained from spectroscopic measurements involving an integrating sphere attachment.