Electrophoretic deposition of particles of a ZnS phosphor doped with Cu and Al has been shown to alter the photoluminescent emission spectrum and thus the chromaticity of the material. The precise alteration of the emission spectra is dependant on chemical composition of the anode used in the deposition process. The effect is partially reversible by a high temperature treatment of the deposited phosphor in air. However, the final chromaticity coordinates of the phosphor are shown to be detrimentally altered compared to their initial values.