During the electrophoretic deposition of phosphor particles at a cathode, a material forms via electrochemical precipitation, which is necessary for adherence of the coating. The chemistry of binder formation was investigated, particularly the effect of water in the bath of isopropanol containing 10(-3) M Mg(NO3)(2). The type of binder material formed is dependent upon the amount of water in the deposition bath. For very low amounts of water the binder material is an alkoxide, Mg(C3H7O)(3). For high amounts of water in the bath (>5 vol %), the binder is predominantly a hydroxide, Mg(OH)(2). At intermediate water concentrations, the binder is a mixture of the two compounds.