Abstract

The diffuse reflectance from a painted layer depends upon the layer thickness. The rate of change of diffuse reflectance when thickness increases is the flocculation gradient, which is valuable information about the degree of pigment dispersion in paint. The simple determination method is called the flocculation gradient technique and is suitable to quantify the pigment dispersions in low-absorptive and high-scattering paints. To make the method useful for black-pigmented paints as well, we modified it by applying the Kubelka-Munk theory. This makes it possible to solve the problem of the very narrow linearity region that appears in the diffuse reflectance vs. thickness curve because of high absorption. The modified method allows one to quantify the degree of dispersion in black thickness-sensitive spectrally selective paints, which are used as absorbers in solar collectors.

Absorption and scattering of light by pigment particles in solar-absorbing paints

Marta Klanjšek Gunde and Zorica Crnjak Orel
Appl. Opt. 39(4) 622-628 (2000)

Kubelka–Munk Coefficients from Transmittance*

B. Patrick Caldwell
J. Opt. Soc. Am. 58(6) 755-758 (1968)

Optical characterization method for black pigments applied to solar-selective absorbing paints

Tuquabo Tesfamichael, Anders Hoel, Gunnar A. Niklasson, Ewa Wäckelgård, Marta K. Gunde, and Zorica C. Orel
Appl. Opt. 40(10) 1672-1681 (2001)

Precision of Determination of Kubelka and Munk Coefficients from Opaque Colorant Mixtures

D. G. Nickols and S. E. Orchard
J. Opt. Soc. Am. 55(2) 162-164 (1965)

Determination of Kubelka–Munk scattering and absorption coefficients by diffuse illumination

Robert Molenaar, Jaap J. ten Bosch, and Jaap R. Zijp
Appl. Opt. 38(10) 2068-2077 (1999)