The Problem-Solution Series: Part 15

Coating Discoloration

Problem: The coating color is not an exact match to the standard. You notice a slight (or substantial) difference from the desired color.

Origin/Cause: It is probable that the oven air is not being exchanged enough to eliminate by-products of combustion.

Solution: Adjust the air exchange rate to reduce the concentration of by-products. For lighter colors, the oven volume must be exchanged several times more than for darker hues in order to minimize discoloration and haze.

Second Origin: The oven temperature may be too high.

Solution: First, reduce the oven temperature. Know the oven profile and set the temperature and dwell time to match the cure schedule. Locate the hot spots in the oven. If the oven is infrared, vary the energy density and the line speed.

Third Origin: The coating formulation may not have sufficient pigment opacity.

Solution: Increase the coating thickness to provide more coverage. For coverage requirements, contact TCI.

Fourth Origin: The film thickness may be too thick or too thin.

Solution: The required thickness for proper color is dictated by the pigment opacity. It may need to be adjusted for proper coverage, which is most likely if the finish is metallic.

For additional information on powder coatings, visit our website at tcipowder.com. Feel free to contact us today to have someone from our experienced team answer your powder coating questions or to see how we can help you with your powder coating needs.