Jolly Green Giants: Why Are Prototype Aircraft Painted Green?

A first flight is a momentous occasion. It’s when years of planning, development, and manufacturing culminates in an aircraft’s first time in the sky, when all that hard work pays off and for most aircraft, they do so while painted in a drab shade of olive green. Why are prototype aircraft painted in such an unappealing shade?

The reason is because aircraft need to be primed before they are painted, and for aircraft primer of choice is a zinc chromate or zinc phosphate that adheres well to the aluminum that aircraft are typically made from. The greatest advantage of zinc chromate and phosphate primer, however, is that it has anti-corrosive properties — a serious concern for aircraft. Prototype aircraft on their first flight will get a layer of green primer to protect against corrosion, but will not get their actual paint-job until later. Additionally, if there are any surfaces of an aircraft that are colored blue, it is because those surfaces are made of lightweight composite materials, not aluminum, and therefore are treated differently to protect against corrosion.

Corrosion-resistant primer was first used by the Ford Motor Company in the 1920s, and adopted for use in commercial and military aviation in the 1930s. United States Army Air Corps documents mention using zinc chromate primer in 1933, and was made standard for use in 1936. Zinc chromate was also extensively used throughout World War 2 by the United States, while Germany and other Axis powers used lacquer-based protective coatings. The British would adopt zinc chromate primer in 1945 for the Martin-Baker MB5.

Despite their unappealing shade, first-flight aircraft are completely functional. They are, however, often almost completely empty as well. Commercial aircraft are first flown without seating or interior decor, for instance, while military aircraft’s first flights are performed without weapons systems mounted. First flights are effectively a proof of concept, showing that an airframe can function properly in the air outside of computer simulations and wind-tunnel testing. Only after subsequent test flights do engineers start installing interior components and slap a coat of paint on.

At Cogent Purchasing, owned and operated by ASAP Semiconductor, we can help you find all the aircraft paints and primers for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at +1-714-705-4780.


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