No more holidays: A tip for metal coating

Tina Gessler and Steven Pine

Abstract

Transparent coatings on polished metals need to completely envelop the surface to provide sufficient protection from corrosion. It can be difficult to detect skips or thin spots in such a coating at the time of application since these coatings are thin, transparent, and nearly invisible when applied skillfully. It is impractical to attempt to assess the overall thoroughness of a coating using methods such as looking for iridescence or using a continuity meter. This tip will discuss an alternative method of coating testing using a small amount of fluorescent laser dye added to coating material. With the addition of the dye, the integrity of the coating can be assessed in ultraviolet light, as skips or thin spots will not fluoresce. Specifics of using coumarin-based dye(s) with both cellulose nitrate and acrylic coating materials will be presented.