"A Change in Paint Might Be the Next Big Thing in the Greening of Cars and Trucks" Green Car Advisor

A Change in Paint Might Be the Next Big Thing in the Greening of Cars and Trucks

The New Black.jpg California is in the process of requiring a change in the chemical makeup of paints applied to vehicles sold in the state. Because the global automotive market is served by only a handful of paint companies, the change will likely affect cars and trucks sold worldwide. Above, standard black paint (left) and a major paint company's current effort at a heat-reflecting black that's much closer to brown.

(Note: T his piece has been updated by an article posted on March 30, 2009. Click here to read the update.)

By Scott Doggett, Contributor

The days of raven-black cars may be coming to an end.

That's because the pigment in automotive paint that darkens colors -- carbon black -- also absorbs sunlight.

The higher percentage of carbon black in dark automotive paint is the reason why the interior of a dark-colored car parked in the sun will generally be much warmer than the interior of a light-colored car parked in the sun only a few feet away.

By reducing the amount of carbon black in automotive paint, parked cars wouldn't get so darn hot on sunny days -- and we wouldn't be so quick to turn on the air-conditioner the moment we slip inside an automobile that's been parked in the sun with its windows rolled up.

Not reaching for the A/C is a big deal in California, because automotive air-conditioners account for 15 percent of the 140 billion gallons of gasoline consumed in the sunny state annually. (The air-conditioners do this by leaching horsepower away from car engines via belt-driven compressors.)

That staggering statistic has California's air-quality regulators -- who by state law must reduce the state's carbon-dioxide emissions to 1990 levels by 2020 -- taking a good look at how they can get motorists in the Golden State to curb their use of air-conditioners.

Their looking has led them to carbon black, a material produced by the incomplete combustion of coal tar and other heavy petroleum products.

If far less carbon black were used in the automotive paint applied to vehicles sold in California, the interiors of cars and trucks there wouldn't become furnaces when parked with windows closed under a hot sun.

And that means California motorists wouldn't be so quick to reach for the A/C switch, which in turn would reduce the amount of gasoline consumed -- and tailpipe emissions spewed -- in California.

The California Air Resources Board is so keen on getting automakers to use less carbon black in the paints they use that the agency is in the process of drafting "cool-paints" legislation that would require them to use less carbon black in paints on the vehicles they sell in the Golden State.

As currently drafted, the proposal would apply to makers of 2012 and subsequent model-year passenger cars, light-duty trucks, and medium-duty vehicles weighing 10,000 pounds or less. It would also apply to collision-repair shops and repainting facilities.

But there's a hitch: The major suppliers of automotive paint worldwide haven't yet figured out how to make the rich blacks, browns and other dark automotive paints that we're so fond of without using carbon black.

"When you remove carbon black and put in either infrared-reflecting pigments or infrared-transmissive pigments, you lose some of the dark color," Connie Poulsen, global director of product management for PPG Industries, told us last week as she prepared to meet with students at the prestigious Art Center College of Design in Pasadena.

Poulsen spoke while drawing our attention to three paint samples: a control sample of standard black paint, as raven-hued as the exterior of a new black Carrera; a sample of infrared-transmissive black paint, which was actually brownish-black; and a sample of infrared-reflective black, which wasn't black at all but rather dark chocolate in color.

Now, you might think there'd be lots of ways for paint makers to match existing colors without using carbon black - and therefore meet the legislation California's air-quality regulators are working on - but that's just not the case, Poulsen said. There are only the two ways: the IR-transmissive paints or the IR-reflective paints.

IR-transmissive paints contain a transparent pigment that allows infrared and near-infrared light to pass through the base layer to a light-colored primer layer, where the warm infrared light is reflected away from the car. This technology allows the paint companies to get pretty close to color-matching existing dark automotive paints.

But - and this is a big but - having a light-colored primer layer would mean that if your car was stone-chipped or badly dinged, a light-colored spot of primer would appear.

In fact, the primer could be very apparent, depending on the difference in color between the primer and base coats. That's why automakers tend to use a primer that's a close match to the base coat.

The other way paint companies are approaching the problem is with IR-reflective pigments, in which an infrared-reflecting pigment is mixed into the base coat. But thus far the paint companies that serve the automotive industry have been unable to achieve the colors they've wanted in what they refer to fondly as "the darker space."

As a result, California's air quality officials are giving the companies more time - until the 2016 model year - to develop the technologies they need to come up with true black, browns and other dark colors that won't heat-up interiors and encourage use of automotive air-conditioners.

For lighter colors - white, silver and light metalics included - PPG Industries, one of the three major automotive-paint suppliers - can meet the legislation today, Poulsen said.

That's a good thing, because while California isn't the center of the universe, it does have a long history of setting trends in the automotive world. Already other western states have expressed interest in following California's cool-paints lead, and few automakers don't wish to sell to California, which is one of the world's largest automobile markets.