Finishing touches

| December 12, 2008

Robots like this one at a Peterbilt plant reduce the cost and weight of the finish by applying a more even and consistent layer than would be possible by a handheld spray gun, making it possible to minimize the thickness of each coating.

Differences in weather, style, body type and affordability dictate how people dress. Similar factors should determine your choice of paint and how it’s applied when it’s time to “dress” your new truck.

After picking the color, the biggest decision you’ll face is whether to apply a single coat (also called a monocoat) or a basecoat plus a clearcoat. The clearcoat is an additional layer of finish that helps protect the paint even though it bears no pigment – that is, no color-producing material. It protects the paint against road chemicals, truck wash chemicals, etc., as well as against the sun’s ultraviolet rays. UV is particularly damaging in that it can alter the shade of the original color.

Price can be a factor, as some truck makers charge extra for a basecoat plus clearcoat, says Joe Wood, fleet segment manager for DuPont Coating Solutions. Others don’t. Volvo, for example, offers only basecoat/clearcoat finishes, says spokesman Jim McNamara.

“On most colors, the truck owner can expect a 30 percent to 45 percent increase in color and gloss retention when they utilize a basecoat/clearcoat system,” Wood says.

That’s a consideration especially if you are going to keep the truck a long time.

Two other factors in making the coating decision are where you operate and what color you’ve chosen.

“In a benign environment, you don’t need basecoat/clearcoat,” Wood says, “but it also depends on the color family. Those bright yellows, reds and white do better when it comes to color and glaze protection. On the other hand, when using medium and ABF [Freight System] green, and anything metallic, use basecoat/clearcoat.”

The extra layer of UV protection makes clearcoat a better choice when running, say, from Florida to Arizona, but it may be better for wintry climes such as Wisconsin’s, too. “Any vehicle that will be used in a harsh chemical environment should have basecoat/clearcoat,” Wood says.

Basecoat/clearcoat also is “easier to clean and easier to deal with,” Wood says. So if you often take the truck through a wash where chemicals are used, or simply can’t wash it regularly by any means, the two-stage finish will hold up much better.

Long before your choice is made, the truck manufacturer makes a critical choice in coating technology that could affect your finish, say Wood and John Lewis of PPG Industries.

“There are two main technologies used today: two-part polyurethanes and one-part melamine paint chemistries,” Wood says. The more commonly used polyurethanes are superior, he says, as they “deliver the ultimate in overall performance, including color and gloss retention, flexibility, chip performance, chemical resistance and scratch and mar performance.” The temperature at which the paint is baked also is lower, which helps protect parts of the cab.

Polyurethane also is more flexible, a desirable quality on thermoplastic cab parts where one-part melamine is more likely to crack.

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