The painting process is the most environmentally challenging part of the automobile factory. It requires extensive—and expensive—air and water treatment systems, as well as recovery equipment to prevent air and water pollution. That’s why carmakers are turning to new technology and materials to make their paint shops more environmentally friendly.

The traditional paint process involves a primer coat that has to be dried by baking in an oven. Then, sprayers apply the basecoat of color followed by a protective clear coat. Finally, the car body goes back in the oven for drying. This process is not only energy intensive, but involves the use of hazardous solvents made up of VOCs—volatile organic compounds—that have to be recovered for safe disposal.

One new way to paint cars and trucks is cleaner, safer and less expensive for the manufacturer and a lot easier on the environment. It’s called “high-solids coating technology,” and it allows the primer, basecoat and clear coat to be applied sequentially before using a single baking stage. The ability to apply a wet basecoat and clear coat on top of a still-wet primer eliminates the need for a separate primer spray booth and oven. This process allows a smaller paint shop that uses significantly less energy.

The new technology also addresses the VOC problem. By increasing the volume of solids in the paint spray, there are far less VOCs to deal with. That makes the environmental protection simpler, more effective and less costly.

Another innovative painting process uses powder and eliminates VOCs altogether, at least for the primer coat. It also reduces the amount of basecoat required to cover the vehicle. The subsequent steps in this process are similar to those in the high-solids method.

The most advanced systems now being commercialized do not use solvents because the process is water-based. While water-based painting is the most environmentally benign of the new methods, it is quite energy intensive. Water-based paints need to be dehydrated and “force-flashed” in the application phase, a process that requires moving vast quantities of air through a humidity- and temperature-controlled, football field-sized drying booth.

In most painting operations, about half the paint sprayed at the car body ends up being “overspray” and must be captured and treated prior to disposal. Paint shops use water and special chemicals called detackifiers to reduce the stickiness of the paint and make it easier to recover. One process now in use involves chitosan, a substance derived from shells discarded by seafood processors. In this process, the water remains reusable for a much longer period and thereby significantly reduces the use of chemical treatments. Up to 60 percent less water is used in such recovery systems, making them environmentally friendly as well.

Environmentally friendly car painting is also migrating to the body shops operated by car dealers. In the face of ever more stringent EPA air quality regulations, car dealerships and body shops are finding it cost-effective to switch to water-based painting.

Water-based paints are safer to handle, easier to use and far less damaging to workers’ lungs and the air they breathe. The equipment simplifies the operation of a painting booth, but does require sophisticated filtration to remove dust from the work area. The paint is applied in pretty much the same way as the old system, but with modified spray-paint guns. Water-based car paint has very little odor and cleans up using soap and water rather than hazardous thinners and solvents.

With the car manufacturers converting to water-based painting operations, the new body shop technology actually results in a better match to the original paint on repainted vehicles.