Comparison of pigment content of paint samples using spectrometric methods

The aim of the paper was to evaluate the influence of pigment concentration and its distribution in polymer binder on the possibility of colour identification and paint sample comparison. Two sets of paint samples: one containing red and another one green pigment were prepared. Each set consisted of 13 samples differing gradually in the concentration of pigment. To obtain the sets of various colour shades white paint was mixed with the appropriate pigment in the form of a concentrated suspension. After solvents evaporation the samples were examined using spectrometric methods. The resin and main filler were identified by IR method. Colour and white pigments were identified on the base of Raman spectra. Colour of samples were compared based on Vis spectrometry according to colour theory. It was found that samples are homogenous (parameter measuring colour similarity ΔE<3). The values of ΔE between the neighbouring samples in the set revealed decreasing linear function and between the first and following one--a logarithmic function.