I am in charge of finishing in our plant. We changed from MIL-L-81352 Flat Acrylic Lacquer to MIL-C-85285 High Solids Urethane (Flat Colors) to meet Environmental VOC requirements. When the inspection department sends the parts back for rework because of any scratches or other surface defects, we can’t seem to spot touchup the urethane like we did the lacquer. We get a “halo effect” and the color and gloss doesn’t appear to match even though we are touching up with paint from the same can used for the original coat. What are we doing wrong? What can we do the correct the situation? T.P.
One of the nice things about using lacquers is their ability to be easily touched up. Since the lacquers are thermoplastic, the solvent in the touchup coat softens the original coat and allows the coat to “blend in.” This is not the case with many of the thermosetting coatings. Although, when I had a real job, I did see a painter who was either an artist or a magician touching-up scratches in a baked enamel finish on refrigerators.
Today, when spot repairs are necessary, an entire panel is repainted. For example, auto body shops repaint an entire door, fender or quarter panel. This is one of the reasons automotive collision repair costs are so high. Unless you have a resident magician in your plant, you will have to do the same. Bite the bullet and repaint the entire panel.