Infrared Reflectance of Paints

The Kubelka-Munk coefficients for paint films in the 0.8-2.0-micro wavelength range are determined from reflectance measurements on films of several different thicknesses over a black substrate. The scattering coefficients S of the paints studied are inversely proportional to the wavelength lambda of the incident light raised to a power p which varies among the paints investigated between 1.5 and 2.5. The absorption coefficients K exhibit a similar dependence on lambda except in the regions of specific absorption bands. The dependence of K and S on the pigment concentration is also discussed.