Studies on a model ink suspension have shown that the effect of non-ionic dispersion agents on ink agglomeration using fatty acid chemistry as collector was highly temperature-dependent. The non-ionic surfactant reduced the agglomeration efficiency at low temperatures (below the cloud point of the surfactant) but this negative effect was reduced at increasing temperatures. At temperatures above the cloud point the non-ionic surfactant improved the agglomeration. The non-ionic surfactant adsorbs to both the ink and precipitated soap particles, which at low temperatures resulted in an increased colloidal stability of the particles but at higher temperatures led to a destabilisation of the particles due to the increased hydrophobicity of the surfactant. The surfactants clearly affected the precipitation of fatty acid anions to calcium soaps and at very high surfactant concentrations the formation of calcium soap particles was drastically reduced. The most favourable conditions seemed to be intermediate surfactant concentrations (0.1 mM). At this concentration the fatty acid was precipitated as small soap particles which, at a temperature above the surfactant cloud point, had good ink agglomeration efficiency. The surfactant improved agglomeration of very small particles, an effect that possibly could be explained by a reduced initial destabilisation rate of the soap particles. A fatty acid collector system produces very fast large aggregates of soap and ink particles, and small residual ink particles cannot easily be incorporated into the large aggregates due to hydrodynamic forces (Johansson et al. 1998). Thus, in a well-balanced system, the non-ionic surfactant may not only facilitate ink detachment and reduce redeposition; it may also promote agglomeration.