The degree of agglomeration and impact strength of Na2SO4 cores (all in the size range of 200-300 μm) coated with aqueous solutions of sodium sulphate and dextrin as a function of several process and formulation variables have been investigated. The coating process was performed in a modified small-scale GEA Aeromatic-Fielder Strea-1 top-spray fluidised bed, and the impact strength was tested in bulks using a Pneumatic Impact Gun, in which granule samples of 0.5 g were exposed to ten repeated impacts at 10 m/s. Using an unreplicated double 24 - 1 fractional factor design, two regression models were derived from experimental data describing quantitatively the degree of agglomeration and impact strength respectively.