Agglomeration has been studied in a laboratory-scale spray dryer by contacting a 20% w/v salt solution dyed with Indigo Carmine as a liquid solution sprayed from the atomizer with dry maltodextrin DE-18 particles that were separately blown towards the atomizer in a Buchi B-290 laboratory-scale spray dryer. The inlet air temperature was 220C, the main air flow rate through the dryer was 38 m3/h (maximum), and the nozzle air flow rate was 667 l/h (40mm on the rotameter), and the outlet temperature ranged from 60-70C.The resulting colour change in the final maltodextrin particles was taken as a measure of the extent of agglomeration. The flow rate of the dyed salt solution was increased from 7.9, 9.2, and 10.8 ml/min, with significant colour change in the maltodextrin particles (compared with the case of no dye) being found only at a flow rate of 10.8 ml/min. However, at this high liquid flow rate, the evaporation capacity of the dryer was almost exceeded, so there is a limited window of operation for agglomeration to occur in spray dryers, where there is a sufficient liquid flow rate to create enough particles to agglomerate, but not so great a liquid flow rate so that the evaporative capacity of the dryer is exceeded.