Q. We refinish metal office furniture on-site at the customer’s premises. We spray a two-part catalyzed epoxy enamel with an electrostatic hand gun. I read in an article about the problem of using solvents for wax removal prior to painting. We agree that solvent wiping is a poor cleaning method for wax removal, and have had a similar problem with wax buildup and other surface contaminants, but are limited as to the methods of surface preparation due to our working conditions. Are there alternative methods that we can use in our work? N.N.
A. While it is true that your working conditions are unique to your business, it is also true that any surface to be painted must be free from oily soils to ensure paint adhesion. Since it’s possible that your customers may have applied wax to office furniture, you must assume they did. Before repainting, I recommend you remove any possible contaminants by a two step process:
- Solvent wipe with mineral spirits applied using clean cloths, changing the solvent and cloths often. Then dry the surfaces using a clean dry cloth.
- Wash any remaining oily residue from the surface with a hot or warm aqueous detergent solution using clean cloths. After rinsing the surface with clear water and clean cloths, dry the surface with clean cloths.
To be effective, the solvent, detergent solution and wiping cloths must be changed often to prevent recontamination of the surfaces to be painted.