The reproducibility and robustness of a unseeded process for the production of high solid content, low viscosity latex are examined. A series of runs showed that the experiments are very reproducible both in terms of the particle size distribution and the shear viscosity of the final latex. It is also shown that it is the surfactant concentration and feed profiles that are the most sensitive issues in maintaining product specifications since they control the rate of generation of small particles. (C) 2004 Elsevier Ltd. All rights reserved.