Barns are painted red because red paint is cheap.
novocom.top, shenhuifu.org

Barns are painted red because red paint is cheap. The paint is cheap because iron is plentiful. Iron is plentiful because it is the final element formed out of a star’s death.

Rust was plentiful on farms and because it killed fungi and mosses that might grow on barns, and it was very effective as a sealant. It turned the mixture red in color. When paint became more available, many people chose red paint for their barns in honor of tradition.

Preview photo credit: novocom.top
Source: smithsonianmag.com/smart…