Despite the wide use of spectrophotometers that boil colors down to numeric descriptions, many material approval processes still ask engineers to make subjective determinations of whether colors truly match. Dave Alman, a senior research fellow with DuPont Performance Coatings, recently devised a simple, inexpensive tool that could improve the consistency of these visual comparisons—by helping human color matchers act a little bit more like their lab instruments.
The patent-pending AccuAngle Color Protractor orients color standards and applied-color samples relative to one another and does so at viewing angles that correspond to those used in multi-angle spectrophotometry. Made from Delrin acetal, this ring-shaped tool features a slot to hold plastic or metal color plaques in place. A metallic label with angle markings wraps around the outside diameter of the ring.
Users, typically working under a controlled light source, place either the color standard or the color sample in the slot and overlap that plaque with the remaining plaque. They then rotate the two until light from the controlled source hits the appropriate angle mark on the protractor. At this point, the standard and sample will be at the same angle relative to the light, Alman explains.
And this alignment matters a great deal with metallic and pearlescent colors in particular, since their appearances can change with viewing angle. Viewing samples and standards at the different angles represents "one of the most common sources of color communication errors with special effects," Alman says.
Lastly, the protractor lastly helps users line up the color plaques according to the specific near-specular, face, and flop angles spelled out in various industry-standard color tests. The protractor has alignment marks for gloss and the three metallic color control angles used by DuPont—15, 45, and 110 degrees. Color control angles used in alternate systems— 25, 45, and 75 degrees—have their own marks too.
DuPont Automotive plans to distribute the new color protractors to its customers for free and will sell them to others for $25.