Obtaining a true black colour before the advent of chemical dyes was extremely difficult. Husks of Juglans nigra, black walnut, have been used to create a deep brown, often interpreted as black in paintings and literature. The first recorded use is in ancient Rome, when walnut was used as a hair dye, an application which was rediscovered across mediaeval Europe. Later, artists including Leonardo da Vinci, Rembrandt, and Van Dyke used drawing inks made from concentrated walnut. It is a long-lasting colour, and as such has been used in Romani culture to stain the hands of criminals- when the dye wore off the sentence had been served.