Techniques: The Passing of Mummy Brown

One of the favorite colors of the Pre-Raphaelite painters was called Mummy Brown — and not out of joking affection. It was a warm pigment made from the bitumen used by ancient Egyptians to embalm their dead, famed for its preservative powers.

But now even Mummy Brown is gone altogether. Geoffrey Roberson-Park, managing director of London's venerable C. Roberson color makers, regretfully admits that the firm has run out of mummies. "We might have a few odd limbs lying around somewhere," he apologized, "but not enough to make any more paint. We sold our last complete mummy...