Why are barns red?

I have always wondered why most barns are painted red. It is always an aesthetic sight to see one while driving in the countryside, both during the lush green days of summer, or the yellow arid days of winter. There is of course a chance that farmers chose the color red for its aesthetics value, but I wondered if there was a more practical reason for the choice.


An online search produced a bevy of results with equally reasonable choices. One of the sites argues that in the older days, one of the practical methods to seal the barn wood and protect it from the elements was to paint it with a mixture of linseed oil, and  additions of milk and line. The red color would come from adding either the blood of a recent slaughter or from ferrous oxide--rust. As the paint would dry it would turn into a dark red color. I buy the rust theory, since there is a lot of rust to be had everywhere, and the blood theory is a bit weird.
The Smithsonian magazine adds a physics spin to the answer, by explaining why rust or ferrous oxide is an abundant material in the universe, and that this abundance is the most likely reason farmers used it in the barn paint mixture. The article explains why iron is abundant through the evolution of stars, as they go from collapse to explosion, and the reactions that combine protons and neutrons into heavier materials as the cycles progress, and finally stopping when the atomic mass becomes 56 (iron). I like the explanation, although it begs the question why the reactions stop at 56. But that's a question for another search.