According to Jerry Apps, author of the book Barns of Wisconsin (www.jerryapps.com):

"Red was the most inexpensive paint that farmers could buy early on. That's the main reason why many barns are red but there are also yellow barns purple barns black barns gray barns yellow barns pink barns. Any color you could imagine is represented on a barn including barns that were never painted at all. And some smeared with waste oil to give a kind of sad looking dark appearance that helped preserve the wood. Barn wood does not need to be painted to last a long time. As long as it remains dry, is allowed to dry out, it will last a very long time so paint is an aesthetic thing in many ways. Now it helps some to preserve. Particularly around windows and doors and that sort of thing but barns will last a very long time if they have a roof and if you take care of the barn wall so it doesn't sag. Painting, that comes later."

This response was part of an interview Jerry participated in as background for a Wisconsin Public Television special titled 'Wisconsin Barns: Stories in Wood & Stone.'   This hour long program is periodically broadcast on Wisconsin Public Television but can also be purchased on videotape for $24.95.  To buy the tape follow the instructions at:

http://www.wpt.org/barns/

You can also read the complete interview with Jerry at: http://www.wpt.org/barns/apps.html