The ionic nature of the components in coating colors is of great importance for the presence or absence of interparticle interactions, which in turn largely govern coating rheology, machine runnability and final paper properties. In the present study two types of starch have been evaluated with repect to their effect on these properties. The aim was to generate different association conditions in coating colors by using anionic or cationized starch, which show clear differences what comes to interaction with anionic clay pigment. Another objective with the study was to evaluate the influence of temperature on the pigment suspensions. Rheological and dewatering measurements were performed and correlated to results from pilot scale coating. It was found that the anionic starch caused a stabilization effect originating from the repulsive forces created between the starch and the equally anionic clay pigment. This colloidally stable system caused no problems in the levelling of coating on the paper, but resulted in a relatively dense coating layer. Starch with substituted cationic groups showed a strong electrostatic interaction with the clay pigment resulting in an aggregated coating system and deteriorated runnability. This was reflected in the final coating as blade streaks due to build-up of coating deposits on the blade during levelling. However, the aggregated coating system resulted in a structured coating layer with a high porosity, which may be desired when printing the coated paper. An increased temperature had a marked effect on the aggregated coating color in terms of a significant decrease in viscosity, while the temperature had a more limited effect on the stable system containing anionic starch. This behavior was also seen in the properties of the dry coated layers, where the open structure of the aggregated color was more affected by a higher temperature than the stable color.