Why red?

One advantage to being 12 years old, as Adam is, is that you wonder why things are the way they are. Old fogies like me tend to have seen so much over the years that we don't ask questions that a kid would ask.

Like, why are most new coal barges painted red? We've seen some that were painted black, mostly with Campbell lettering on them, and Adam says he's seen a photo of a green barge, but why are coal barges painted a red that's almost maroon? His theory is that maroon matches the color of rust, so when the paint wears off and the steel starts rusting, you're less likely to notice.

But now he's wondering about the colors of barges, meaning the question will bug me, too.