AbstractThe conditions under which electrophoretic deposits can be formed from suspensions of a number of metallic and non‐metallic materials have been established, and the zeta‐potentials of the materials have been measured. Calculated values of the minimum field‐strength required to overcome the repulsion between the particles show agreement with the observed values for some materials. For other materials, particularly metallic powders, it is not possible to apply sufficient force by the field to overcome this repulsion. Addition of a suitable amount of certain electrolytes, for example 10−3M‐aluminium chloride, results in very adherent deposits. Under these conditions the electrolytic reaction produces a binder, such as a polymeric hydroxide, at the cathode, so that the adhesion of the deposit no longer depends only on the London‐van der Waals attractive forces between the origina