E-coat is an emulsion of organic resins and de-ionized water, which is in a stable condition. The e-coat solution also comprises of some solvent and some ionic components. When a D.C. voltage is applied across two immersed electrodes, the passage of current is accompanied by electrolysis of water. This results in oxygen gas being liberated at the anode (positive electrode) and hydrogen gas liberated at the cathode (negative electrode). The liberation of these gases disturbs the hydrogen ion equilibrium in the water immediately surrounding the electrodes. This results in a corresponding pH change and this in turn de-stabilizes the paint components of the solution and they coagulate onto the appropriate electrode.

Electrolysis of Water

Electrophoresis is a well documented process whereby electrically charged particles in a conductive medium will migrate to the electrode bearing the opposite charge under the influence of D.C. voltage. Although many technical descriptions of electropaint ascribe electrophoresis to the deposition process it is not the predominant mechanism. However, it is very common to refer to electropaint as "Electrophoretic"