Pigs have bristles on their back. The relatively short, stiff, coarse hairs of the pig are called bristles, and were once so commonly used in paintbrushes that in 1946 the Australian Government launched Operation Pig Bristle. In May 1946, in response to a shortage of pig bristles for paintbrushes to paint houses in the post-World War II construction boom, the Royal Australian Air Force (RAAF) flew in 28 short tons of pig bristles from China, their only commercially available source at the time. Their coats are coarse and bristly. They are born brownish colored and tend to turn more grayish colored with age.