Replacement metal parts are generally covered with a black primer called “e-coat” in the industry. But what exactly is this primer?

E-coat, also known as electro-deposition, is a unique coating process that combines painting and plating. Developed over the past 50 years, it has evolved into a high-tech coating process and revolutionized automotive painting when it first appeared.

Compared to solvent-based powder coating, electro-deposition offers more complete coverage, uniform thickness, no overspray issues, zero flammability, and the ability to process both dry and wet parts.

How does it work?

First, parts are meticulously washed with a solution often composed of phosphate, then rinsed with deionized water. This increases the metal’s conductivity and ensures good adhesion for the next stage of the process.

They are then immersed in a constantly agitated solution composed of approximately 80 to 90% deionized water and 10 to 20% epoxy resins and pigments, which make up the primer. An electric current is applied to the parts to make the primer adhere uniformly to the inside and outside of the parts, even if they have complex shapes.

The same process is used by manufacturers where vehicles’ metal bodies are completely immersed in large tanks for treatment. The electrical voltage applied to the part will determine the coating thickness. Once removed from the solution, the part is rinsed again to remove any excess solid particles that may have remained on the surface. The part is then baked at 190°C (375°F) for 20 minutes.

Although the primer is very thin, generally around 12 microns, it offers excellent anti-corrosion protection to the part that cannot be matched by liquid primers used in refinishing. Benefits include excellent adhesion and exceptional durability.

This is why it’s important to avoid over-sanding the part or removing the primer when preparing parts.

Environmental benefits

Electro-deposition offers increased efficiency and environmental safety. Indeed, this environmentally friendly technology primarily uses water as a carrier and utilizes 95% or more of the coating to form a primer thickness on the part, thereby reducing emissions of volatile organic compounds (VOCs).

Electro-deposition is particularly beneficial for the automotive industry, offering protection against rust and increased durability. It also helps reduce CO2 emissions from automotive plants.

Electro-deposition is incredibly versatile and used in a variety of consumer products, such as jewelry, eyeglass frames, or electronic devices, for example. It is essential for industries looking to optimize their coating processes. It offers uniform coverage, excellent durability, and reduces application costs while being environmentally friendly. This process remains a key player in the composition of modern automotive coatings.