Color and appearance are key factors in the purchase of a product. Eye-catching finishes draw the customer’s attention to the product and help give the impression of added value. Automotive manufacturers learned this lesson long ago and now use effect pigments (metallic-flake and interference pigments) in many of their coatings.
Coatings that contain effect pigments change appearance as the illuminating and viewing angles change. This phenomenon is called gonioappearance, and the changes in appearance can be very dramatic. While designers love the visual effects achieved by using these effect pigments, the very aspects that make these pigments so visually appealing also make them uniquely difficult to characterize and control. As the development time from concept color to finished product becomes shorter, the challenge to formulate, correct and evaluate gonioapparent pigments grows.
For years, the color of paint has been controlled using spectrophotometers. However, conventional spectrophotometers, using either integrating spheres or 45°/0° illuminating/viewing geometries, cannot measure or characterize samples containing gonioapparent materials.