We have all seen red barns speckling the farming landscape and I'm sure, that we have all wondered why barns are painted red.
There are several theories as to why barns are painted red. Centuries ago, European farmers would seal the wood on their barns with linseed oil, a tawny coloured oil derived from the seed of the flax plant. They would paint their barns with a linseed-oil mixture, quite often consisting of additions of milk and lime. This combination produced a long lasting paint that derived and hardened quickly. Historically, the "barn red" term is not the bright, fire engine red that we see today, but more of a burnt orange red. How the oil mixture became traditionally red, there are basically two theories:
Wealthy farmers added blood from a recent slaughter to the oil mixture. As the paint dried, it turned from a bright red to a darker, burnt red.
Farmers added ferrous oxide, also known as "rust", to the oil mixture. Rust was plentiful on farms and acts as a deterrent to fungi, including mold and moss which were known to grow on barns. As fungi grows it would trap moisture in the wood, increasing decay.
As European settlers crossed over to America they brought with them the tradition of red barns. In the mid to late 1800s, as paints began to be produced, red paint was the cheapest to buy. Red was the favourite colour until whitewash became cheaper at which point white barns began to appear.
Today, barns vary in colour, but many have kept with the tradition of the "red barn."