She [Lucrezia] also had bright yellow hair, which she washed once a week with a mixture of saffron, box shavings, wood ash, barley straw, madder, cumin seed, and one thing and another to bring out the hidden glints and restore its natural color. You left it on your head for twenty-four hours and washed it off with lye made from cabbage stalks, the only hazard of which was the second-degree burn. If your hair remained on the scalp, you were a blonde.

The Decline and Fall of Practically Everybody (1950) - Part III: Strange Bedfellows - Lucrezia Borgia