What is electrophoretic coating?

Electrophoretic coating (hereinafter referred to as electropainting) is a painting process which is extensively used in industry to coat a wide range of metal components. Its primary use and development has been within the automotive sector but it also has many other applications. The electropainting process is most often available commercially in black (other colours are however possible but much less commonly used.)

The process typically involves a number of stages including a cleaning stage followed by a phosphate conversion coating which enhances the corrosion resistance of the metal and also provides an improved base for the subsequent coating. After the metal is properly prepared the electropainting process can take place. This is then followed by an oven curing stage.

The complete process stages at Euro Quality Coatings are as follows:

Alkali Cleaner
Water rinse
Refiner rinse
Zinc phosphate pre-treatment
Water rinse
De-mineralised water rinse
3 stage ultra-filtration rinse

There are many different terms used to describe the electropainting process and these fall into 3 main categories; they relate to the process itself, the type of electrode used and the trade name of the bath material used:

The process
Terms such as electrophoretic coating, electrodeposition, electropainting and electrocoating describe the process whereby a pigment is deposited onto a component by means of an electric field. The terms e-coating and e-coat also refer to this process.

Electropainting is usually achieved through submerging the components into the electro paint bath and applying an electrical charge through the bath.

The type of electrode
There are two types of electrocoating; they are known as anodic and cathodic.  The anodic process was the first to be developed commercially but now the cathodic process is more widely used.  In the anodic process, negatively charged material is deposited on the positively charged component (this is the anode). In the cathodic process, positively charged material is deposited on the negatively charged component (this is the cathode.) The process used at Euro Quality Coatings is the cathodic type and can be called by various names including: cathodic dip painting (CDP), cathodic dip coating, cataphoretic coating, cataphoresis and cathodic electrodeposition. This process may also be described by German based specifiers as KTL (Kathodische Tauchlackierung – cathodic dip painting.)

Trade names
The electrocoating process may also be referred to by the trade names of the bath material used for example:

BASF – Cathoguard
Du Pont – CorMax
PPG – Powercron
FreiLacke – Freiotherm