Q. We are powder coating parts made from a mild steel substrate. What are both the ideal and the maximum surface temperature the metal should be when applying powder?— L.M.
A. I would say the preferred temperature is ambient and the normal recommended maximum is around 120°F. Parts that require very heavy film build can be coated at higher temperatures, but remember that higher temperatures will increase smoke and also generate a warm air updraft in the powder booth. Powder will melt at temperatures between 180° and 240°F. If the powder melts, you will not have as much flow during the cure cycle, so the material will have a lot of orange peel and heavy film build. It may also smoke a lot during application. Parts can be coated with fusion bond epoxy (FBE) at very hot temperatures (400°F or higher), but not with any decorative powder.