Why is it that so many barns (that sit outside in the full sun all day) are painted red? Don't farmers know that red fades in the sun?! Actually, I googled it…and there are several theories. One involves farmers sealing the wood with linseed oil, which has an orange/red color. Another says farmers would put ferrous oxide (aka rust) in the oil because it was poisonous to molds and fungi which would increase the decay of the wood. Red was also the least expensive color of paint, and last, there is an unappealing / yucky theory that I'll keep to myself, or you can google it.