Q. I am the quality specialist for a first-tier supplier to the automotive industry. In one of our product lines, we injection-mold parts, then paint and assemble them in this facility. We are having a problem painting an ABS injection-molded part, with dark, cloud-like spots and long parallel splays. The defect is consistent in location on each molded part. Can you help? J.C.
A. Although I worked with plastics many years ago, my area of expertise is organic coatings, not injection molding. Since the paint defect is in the same spot on every part, I believe you have a molding and not a painting problem. On the other hand, surface defects are often telegraphed through a coating. In that case, the problem can be solved by increasing the paint film thickness.