A two-dimensional airblast atomizer with variable gap width (in the range 0.25 - 0.75 mm) has been used with a high pressure atomization test rig and a Malvern 2600 drop size measurement system to determine the influence of film thickness on Sauter mean diameter (SMD) for sprays produced by atomizing several coal water slurries. Varying air/fuel ratio and airblast velocity has demonstrated the dependence of SMD on these parameters for three gap widths. Specifically. SMD increases with increasing film thickness and decreases with increasing airblast velocity and air/fuel ratio. The percentage of droplets larger than 200 microns increases with film thickness indicating that application of prefilming atomizers to slurry combustion in gas turbine engines will require minimum fuel thickness for the most efficient burning.