Well-defined poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core shell particles with a moderately high solid content (49%) and particle diameters of less than 200 nm were prepared via seeded emulsion polymerization with a redox initiator and an anionic surfactant. Low-viscosity (less than 150 cps at 20 s(-1)) latex products were obtained by controlling the particle size distribution to within certain limits. Polymerization conversion and kinetics were followed gravimetrically and were adjusted so as to obtain recipes that could be scaled-up for industrial production. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115:2668-2676,2010