Just as you would apply primer before painting your house, Boeing sprays primer on airplanes before putting on an airline's livery.
But because jetliners are made of aluminum, airplane primers contain a critical ingredient house primers don't: chrome, which helps paint adhere to the fuselage and, more importantly, prevents corrosion.
"Chrome performs very well as a corrosion-inhibitor on our current airplanes," said Randy Jahren, a technical fellow in Boeing's Research & Technology group.
Jahren, though, has spent years working on getting rid of chrome because it is also a toxic metal that can pose a health hazard during the application and removal process.
"So what we're trying to do is use a product that will be non-toxic and give us the same corrosion protection to the airplane itself," Jahren said.
Over the past few years, Jahren and his team of engineers have evaluated different formulas of chrome-free primers. They applied them to aluminum panels and exposed them to some of the punishing weather conditions that airplanes encounter every day.
After exhaustive testing and evaluation of hundreds of aluminum samples, the team is confident they've finally found one that fits the performance requirements.
Earlier this year, that chrome-free primer was applied to several Next-Generation 737-800's to complement the chrome-free exterior decorative paint that has been in use for more than a decade.
Airlines are now flying those jets as part of a four-year in-service evaluation. If the new primer holds up as predicted, the goal is to offer it for all aluminum airplanes that Boeing delivers.
"It would be very good for the environment, good for our employees painting the planes, and good for airline employees who remove paint from the planes," Jahren said. "They will no longer have chrome to treat and dispose of."