Time and media change the properties of pigments color

I am present a physically based model for predicting the visual appearance of artists´ paint, which is dependent on both time and the material that binds the colorant to a surface(media). In our study, I captured the reflectance spectra(using spectrophotometer) of a large number of paint samples at different intervals in time over the course of three months. These paint samples are handmade to ensure material quality, using various pigmented colorants and adhesive binding media. Converting our spectral data into different perceptually uniform color spaces, I show very significant perceptual differences in two domains, they are 1) The appearance of paint changes over time 2) The appearance of one pigmented colorant varies when dispersed in different materials. Finally, I present an interactive viewer for predictive pigmented color mixture utilizing the paint reflectance spectra, Kubelka Munk (KM) theory and modern graphics hardware in computer.