Wrong Color of Powder

Q. Our condo manager has consulted with a powder coating material supplier for a paint process for replacement balcony railings on the ocean. After a 1,000-hour salt chamber test and other performance testing, he ended up ordering the incorrect color of powder coat.

1. Is it true that one cannot change the color of an existing batch of dry powder coating material?
2. The manager wants to get the correct color by applying a liquid polyurethane paint or an enamel paint on top the powder-coated surface. My gut tells me that is not a good idea, and it would not last and might flake off. Am I correct?
3. If the above two options are not viable, what options are available? R.L.

A. It is true that you cannot change the color of the dry powder. Powder is melt-mixed to blend the dry ingredients, and it cannot be changed by adding dry ingredients.

If the powder is already applied but the railing not yet installed, you can scuff sand the surface and apply a second coat of the correct powder color over the incorrect color. If the rail has been installed already, you can apply a polyurethane liquid paint over it if you prepare the powder surface by roughening it with sand paper. A lot of labor there, but it will work. I would sand and then prime, then apply the polyurethane.