Here’s Why New Boeing Aircraft Are Painted Green

At first glance, a freshly built Boeing 737 appears to have an odd green patchwork that might look like a shoddy paint job from a sketchy shop. In reality, the green coating on newly assembled Boeing airplanes serves a crucial purpose, one that helps keep the aircraft intact and its passengers safe. 

The paint isn’t really green. No, you’re not color-blind. The paint is yellow out of the box and acts as an anti-corrosive primer, helping to prevent the plane from corroding. This zinc-chromate coating — first used in the automotive industry by Ford in the 1920s, and later in commercial and military aircraft — turns from yellow to green when lampblack is added, offering resistance to the sun’s ultraviolet rays. 

Modern aircraft are made using Alclad, an aluminum alloy that’s corrosion-resistant by nature, as well as being incredibly strong and durable, which makes it perfect for building airplanes. Still, aircraft manufacturers such as Boeing apply anti-corrosive primer to add an extra layer of protection. This safeguards against long-term corrosion and helps minimize the risk of metal fatigue, which could weaken the structure and ultimately prove catastrophic.

If you’ve ever seen an aircraft in its “birthday suit,” you may have noticed different shades of green across its surface. This is because various components are made by different manufacturers, or by different divisions within the same company, which may use a different brand of primer, resulting in color differences. Some sections of unpainted planes are also in white or beige; these are components made of composite materials, which don’t corrode and so don’t require the zinc-chromate coating.

The next step in the aircraft-building process is to apply the paint, and the zinc-chromate coating plays an important role here, too. The primer helps in binding the paint to the aircraft structure, aside from its primary role of preventing corrosion. Boeing uses a dark green primer, while Airbus and Gulfstream use olive and light green, respectively, as their primers.

An airplane’s tail is often painted before the rest of the plane, as the vertical stabilizer plays a crucial role in the aircraft’s aerodynamics, so it must have the right weight and balance. The rest of the aircraft is then painted on top of the primer, usually in white. The airline’s logo and livery are added next, and finally, a layer of clearcoat. Airplanes usually cost $175,000 to $200,000 to paint, with top manufacturers like Boeing and Airbus operating their own painting facilities while also outsourcing work to specialized airplane painting companies.

Painting an aircraft is, as expected, a long and arduous process, usually taking one to two weeks to complete. However, an aircraft isn’t painted just once in its lifetime, as periodic maintenance is required to ensure that there’s no corrosion, while also maintaining its aesthetic appeal. It typically needs to be repainted every six years, which involves stripping off the old paint and repeating the entire process — including applying the green primer once again.