PPG Industries has developed a water-based corrosion protection primer that is applied to aircraft metal parts using an electrocoating dipping process, eliminating the waste and environmental concerns linked to sprayed primers.

Kevin Brooks, global segment manager for OEM coatings at PPG, said priming today is done by workers with spray guns in paint booths, where only about 25 percent of the paint ends up on the part, leading to inefficient use of primer and environmental concerns with workers breathing the airborne chemicals used in the primer.

For parts that have complex recesses, Brooks said the hand spray process can lead to 4-5x the desired thickness of primer near the recess area to ensure full coverage.

Based on electrocoat technologies that have been used in the automobile industry for more than 40 years, PPG has developed its Aerocron primer for dipping applications, where coating thickness is tightly controlled to minimum levels across the entire part, cutting weight and boosting coating utilization to nearly 100 percent.

Electrocoating, or electrodeposition, uses electrical current to apply a coating to a conductive substrate submerged in a water-based paint bath. The process can be fully automated said PPG.
Brooks said the primer has taken several years to develop, in part due to the requirement of aerospace aluminium alloys for lower cure temperatures compared to automotive alloys.

He said “several” OEMs in Europe and North America, as well as military customers, are evaluating or implementing electrocoat-application primer on small-scale projects, eying the technology for their next generation primer needs.