Interaction between ink particles and air bubbles has been determined by contact angle and flotation experiments. Different parameters have been tested concerning their effect on these interactions. The contact angles for the ink-soap agglomerates were much lower than expected, which means poor interactions between the solid surface and the air bubble. The angles were in the range between 18° and 63°, indicating an area for improvements. The angle was improved by increased electrolyte concentrations, a hydrophobicing agent (AKD), a non-ionic surfactant, increased amount of calcium soap and strangely enough with CMC. The contact angle has to be more than 50° (Dalmijn 1995) for flotation of large particles while lower contact angles can be accepted when flotating smaller particles, due to hydrodynamical reasons. No correlation between surface tension of the liquid phase and the contact angle was observed. This indicates that the contact angle is mainly determined by the hydrophobic/hydrophilic property of the solid surface. The flotation experiments showed that a high agglomeration efficiency (right size) is more important for the flotation than a high contact angle. Actually all chemicals with dispersion properties i.e. CMC, starch and non-ionic surfactants, decreased the flotation efficiency.