Bright, Custom E-Coat Colors

Q. We have a liquid paint system and would like to switch to a more environmentally sound coating system. Engineers in our company say that e-coat is not suitable for us because of the bright custom color we have. Can you customize electrocoat to match a specific color?—B.F.

A. Epoxy electrocoat formulations do not have any constraints on the color of the liquid paint as received by the user, as long as it is a solid color, such as a RAL, and does not have any metallic or specific visual effects. You can choose any color to match your specific requirement or use clear coat, ranging in gloss from <10 to >65°.

The issue with epoxy electrocoat formulations is that, although the color of the liquid paint as received is a perfect match, that color can’t be obtained consistently in operation during the curing stage. The color of the cured parts will differ from piece to piece, depending on the specific degree of cure received by each part, depending of the mass of each piece. This issue with epoxy formulations is referred to in the industry as color stability during curing, and epoxies are known for having poor color stability during cure. 

For example, I have seen systems where the paint itself was a typical “construction yellow” in color, but some parts came out of the oven anywhere between light and dark brown. Epoxy systems must be specified and accepted as a color range or color ladder. This color ladder can be duplicated in the lab so that the color variation can be known and accepted. 

On the other hand, acrylic formulations or hybrid formulations (mixtures of acrylic, urethanes or epoxies) can enable the color of the cured parts to consistently match the color in the liquid form, independent of the degree of cure obtained. In this case, you can also choose any color to match your specific requirement as long as it is solid and without effects. The gloss of the acrylic formulations can reach 90°-plus for highly visual applications.