Why are tropical animals so colorful? Archaeologists discover that parties 11,000 years ago were BYOB — bring your own boar But barns weren't originally red in fact, they weren't painted at all.

Why are so many barns red? Barns, like houses and other buildings, could be any color you choose, but red seems to be the dominant barn color. Before 1800, very few barns were painted.

So they needed a cheap way to protect the barns' wood. They mixed skimmed milk, lime, and red iron oxide to make a red, plastic-like coating.