Referring to human relations, my father advised me always to "save the surface," which is something like "don’t burn your bridges," only more subtle. The connection between the homilies becomes literal in the paint industry: You must save the surface of an iron bridge to avoid burning or corroding its basic structure. Color is a distinctly secondary objective to structural preservation in the painting of such things as bridges, water towers, and battleships. Sometimes, however, the means to the objectives agree: In the case of the Golden Gate Bridge, the red primer retarded rust, was visible to aircraft through fog, and was much more aesthetically pleasing than the U.S. Navy’s alternative coloration of yellow and black stripes. So red was the chosen color.Sometimes color technology—which is based on the interaction of lights, pigments and human vision—also helps in the quality control of a paint job: Additives to the paint can accentuate the visibility of flaws and predict future corrosion sites. This approach helped solve a problem faced by the Navy. Aboard ocean-going ships, tanks that hold drinking water or ballast are vulnerable to slow breaches caused by corrosion that starts where paint covers the inside of the tank imperfectly. Under ultraviolet (UV) light, fluorescent paint makes defects visible 4–5 times as far away as would be visible with a flashlight. Fluorescent materials transform incident UV energy to visible light, so it’s possible to see painting flaws in an otherwise dark room.

At first, portable, cheap UV light wasn’t available. Paint-job quality control on a naval ship had to be done by clambering around in very tight spaces with heavy, delicate, expensive UV sources. But recently, light-emitting-diode (LED) technology allowed near-UV radiation at 365 nm to be emitted by a $50 source the size of a flashlight.

Now Paul D. Gossen, of the National Surface Treatment Center in Louisville, Kentucky, is promoting a new way to enhance visibility of paint flaws: Add a special fluorescent material to the paint and then use an LED flashlight that emits light at 405-nm that’s visible and, hence, safer than UV for eyes). The light itself is deep violet, hence not very bright, and causes the applied paint to fluoresce so brightly that subtle material defects glow visibly even in a brightly lit conference room. That feature is important because in many industrial environments, it’s unsafe or impractical to turn out the room lights to look for paint flaws. Gossen approached the American Society for Testing and Materials with a proposed standard for the light. That proposal has been approved and the new standard is designated E2501-06. Now Gossen seeks to standardize the properties of the fluorescent material in the paint. Once paint manufacturers buy into the standard, we may see fluorescent paint-additives used for bridges, water towers and other things that are too large to be made under the careful auspices of a factory.

Soon, when you turn on your faucet, the reliability of the result may depend on fluorescent paint additives that, under watchful eye, have “saved the surface” of your town’s water tank. And color technology will have reached you in a vital—not just aesthetic—way.