A thermally active polymer, ethyl hydroxyethyl cellulose (EHEC), was evaluated with respect to its ability to generate temperature-induced interactions between components in coating colors. At low temperatures the polymer is water soluble, providing a good flow behavior to the color. As the temperature is raised a phase separation of the polymer takes place, inducing an interaction between the components in the color. Rheological measurements showed that using EHEC as thickener resulted in a significant temperature-induced viscosity increase of the coating color. The increase in viscosity was found to be a result of interactions taking place between the three-component system consisting of EHEC, latex and pigment. The increase in viscosity with increasing temperature was further shown to correlate with the styrene/butadiene ratio in the latex. It was also found that a higher amount of EHEC was adsorbed on English clay than on ground calcium carbonate. This affected the degree of interaction within the three-component system EHEC-latex-pigment, in that the increase in viscosity with temperature was lower when English clay was used. However, when delaminated US clay was used, a strong temperature effect was detected.