Electrocoating (E-coat) is a process in which electrically charged particles are deposited out of
a water suspension to coat a conductive part. During the electrocoat process, paint is applied to
a part to produce a uniform film thickness, that is regulated by the amount of voltage applied.
The deposition is self-limiting and slows down as the applied coating electrically insulates the part. E-coat solids deposit initially in the areas closest to the counter electrode. As these areas become insulated to current, solids are deposited in more recessed bare metal areas to provide complete coverage. This phenomenon is known as throwing power and is a critical aspect of the electrocoat process. E-coat is a technology used worldwide to achieve high-quality, low-cost  finishes at a level of efficiency and environmental compliance no other finishing method approaches. The performance advantages, along with reduced finishing costs, have made it a growing technology that will continue long into the future as new uses and technologies are developed.

For your convenience B.L. Downey Company LLC has provided links to various websites where you can find more information about E-coating:

www.pfonline.com/articles/pfdmerlo01.html

www.electrocoat.org