In the field of ED coating, the working voltage (or coating voltage) of ED coating is the voltage applied between the two poles to achieve excellent paint film appearance and specified paint film thickness. The painting voltage has a certain range. When it exceeds the upper limit of the painting voltage, the reaction on the electrode intensifies, producing a large amount of gas, causing the deposited paint film to explode, break down, and produce abnormal adhesion. This voltage value is called the breakdown voltage.

On the contrary, when the voltage value is lower than the lower limit of the working voltage, almost no paint film can be deposited (or the deposition and re dissolution of the paint film are offset), and this voltage value is called the critical voltage. The working voltage of electrophoresis is between the critical voltage and the breakdown voltage.

Working voltage is one of the important process parameters for ED coating. Under the premise of keeping other  coating conditions constant, the thickness of the  coating film and the penetration force are directly proportional to the coating voltage. During the production process, adjusting the coating voltage is often used to control the thickness of the coating film.