We’ve all seen it: a deep and vibrant color used as either an accent band or the dominant color of a building. As the weeks pass, months, or if the owner is fortunate, years, the once bright and recognizable corporate color has all but washed away. Brilliant colors such as red, green and blue, once proud company identifying logos, have transformed into dull lifeless shades.
This change is nothing more than a manifestation of a color fade, correct? We are of the understanding that bright, rich and deep colors are not stable when exposed to the scorching rays of the sun. They can change in appearance quickly; a color that once was an intense cherry red has been transformed into the color of heartburn medicine. Color stability is the most important aspect in keeping the original appearance sharp and bright, right?
Without question color stability can have a sufficient impact on how a specific color is perceived. However, just as important, and in some cases even more important, is gloss stability. When we watch the appearance of a coating transform from a glossy bright color into a chalky, dull faded shade, both color and gloss retention contribute to this change.
Observe the picture to the left; this panel has been coated with a standard polyurethane on the left, and in the same color, an ambient cured fluoropolymer on the right. As a control area, the upper part of the panel has been covered to prevent exposure to that portion. This panel was then put into a QUV cabinet and subjected to 10,000 hours of exposure.
The left side, the polyurethane, has a very apparent change in the exposed area and the obvious conclusion is color has all but faded away. However, a reading from a spectrophotometer, a device designed to read color, tells us we only have a color difference of 2.1 Delta E. While 2.1 Delta E is a slight shift in color - roughly 1 Delta E is a color difference discernable by humans - it is not a significant color change.
Much more impactful is the extreme loss of gloss and how we perceive this change. A reading from a gloss meter indicates an initial gloss reading of 78, while the exposed portion of the polyurethane has faded to a reading of 3. The once high gloss coating has dulled to a reading of ultra-flat and our eyes incorrectly recognize this flattening of gloss as a substantial change in color.
How we perceive color and gloss change is of interest, however, even more noteworthy than the change in appearance with the polyurethane is the lack of change with the fluoropolymer. This air dried coating, which can be roller, brush, and spray applied to all types of substrates, offers both the color and gloss protection once only available with a baked on finish. Clearly recognizable, the fluoropolymer, on the right side of the panel had no appreciable change in either color or gloss after the 10,000 hour test.
Recognizing how exterior exposures can significantly change appearance, coating selection can clearly have an impact on color and gloss longevity. Polyurethane, the standard of high quality coatings for over 20 years, clearly “pales”, when compared to a fluoropolymer finish. Exterior exposures can have a significant impact on the long-term color and gloss retention of a coating, making the selection of that product an important part of maintaining a quality appearance on a structure or building. As highlighted above, a coating’s gloss retention plays an important role in the perception of color, therefore both color and gloss performance levels should be examined conjunctively prior to product selection to establish an accurate expectation of its overall appearance.