White E-Coat

Q. Our company sends many of our steel stampings out for black epoxy E-coat. These parts are all internal structural members of our products. We are very pleased with the performance of E-coat.

However, we have designed a new product that has a steel component that will be an external member. The surface will be highly visible, it must be white, we want the durability of E-coat and it needs to look good. The production manager at the company who does our E-coat work says that E-coat only comes in black. Is she missing something? I thought I saw an article a couple of years ago in PRODUCTS FINISHING about a company using white E-coat.

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Is it possible to get white epoxy E-coat? M.H.

A. I would say the person who told you that is correct if she was talking specifically about that company’s electrocoating operation. They obviously have black E-coat in their tank since they are coating your other products black. So, that is her frame of reference.

Technically, E-coat is available in many colors. However, once you fill a coating tank with a black E-coat paint it is very, very difficult and not economically feasible to change back and forth between colors.

You mentioned that you are having a black cathodic epoxy E-coat material applied to your internal components by a custom E-coater. Also, the E-coater probably coats a lot of products for the automotive industry. The pretreatment will be very good and that coating system will yield excellent corrosion resistance and durability for your applications. However, the cathodic epoxy E-coat material is not designed to be used as a finish top-coat where the product will be exposed to sunlight. The ultraviolet rays from the sun will cause a white or chalky film to develop on the epoxy surface. If you were to use a white E-coat, you would probably want another resin base such as acrylic instead of epoxy.

There is a way you can have the excellent corrosion protection of epoxy E-coat and still have the white decorative surface you are requiring. Go ahead and have the black E-coat applied, and then have a powder or liquid top coat applied in the shade of white that meets your design criteria.