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Flex Products - Tips on Tints

Today's Urethanes Offer Endless Combinations of Colors

Michael Breeding Apr 1, 1999

Step By Step

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Here we see the tiny light interference pigment flakes from Flex Products under the evil eye of the electron microscope. These flakes are one-fiftieth the thickness of a human hair.

It's amazing how far we've come when you consider the early days of painting your rod or custom. In the beginning it was pretty easy: lacquers or enamels in hot rod red, jet black, or keep it simple and leave it in primer. Next came metallics, candies, and pearls that made you wish the early R&C "Little Pages" were done in color. Eventually color made it to the printed page, and hot rodders everywhere could see what these fabulous groundbreaking colors could do for a car. We saw wild flames, scallops, and fadeaways being sprayed in backyards across the country.

Incredible technological advances have been made in automotive paint since those early days, despite being squeezed by environmentalists. It’s sort of like comparing a B-17 to a cruise missile or a stocker 1932 Ford to a 1999 Prowler. Today it’s urethanes in basecoat/clearcoat with endless combinations of colors in metallics, candies, pearls, and candy basecoats. Now comes the next level in automotive finishes--color-change paints: The perfect choice for someone who simply can’t decide what color to choose.

The Essence

Much of the technology for the pigment used in this special color-change paint comes from Flex Products, which supplies the pigment for Valspar/House of Kolor, PPG, DuPont, BASF, Sikkens, and many other foreign paint companies. Flex Products talked to us about two different types of color: absorptive color and interference color. Absorptive color is a type of material that absorbs some wavelengths of light and reflects others, allowing you to see the color it reflects. Interference color is created by the constructive and destructive interference of light waves in the visible spectrum. According to Flex, the best way to understand this color condition is to look at nature: the shifting colors of a peacock's feathers or the rainbow found in a soap bubble. Both of these are caused by thin micro-layered structures reflecting different light wavelengths, depending on the viewing angle and their position to the light source.

The patented Flex process called "Color by Physics" recreates this phenomenon in an opaque microscopic reflective flake. Its ChromaFlair pigment is produced using these tiny flakes. In this process, the tiny flakes are created with five layers of material. Despite being five-layers thick, the flakes are only 1 micrometer thick (about one-fiftieth the thickness of a human hair). The center is comprised of an opaque reflective layer with a glasslike reflective layer on each side. Next to the two glasslike layers are a pair of semitransparent absorber layers. The different colors are produced by precisely controlling these two outer layers, which in turn affect what light is absorbed or reflected depending on the angle you view it from. Remember, this is done to each microscopic flake that goes into the pigment, which in turn ends up in this special paint. As you can imagine, the technology and the cost to produce smooth and consistent microscopic flakes for this pigment play a major role in why this paint is so expensive.

Another interesting aspect of this new technology is the fact that the ChromaFlair pigments can be used alone, together, or in combination with other conventional pigments. Eight basic colors are available, with a possible 36 color variations created by mixing different levels of the original eight, which are as follows:

Red/Gold (shifts from red through orange and yellow into green)

Silver/Green (shifts from silver through the full range of greens into purplish blue)

Gold/Silver (shifts from gold to bluish silver)

Green/Purple (shifts from green through blue and red into orange)

Cyan/Purple (shifts from cyan through purple into reddish orange)

Blue/Red (shifts from blue through purple to warm red)

Purple/Orange (shifts from purple through red into orange)

Magenta/Gold (shifts from magenta through red, orange, and gold into yellow)

For the continuing story, check out the sidebars below.


Wilmington, DE 19898
PPG Industries
Pittsburgh, PA
Flex Products
Santa Rosa, CA 95407

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