Marrakech Red Natural Vegetable Dyes
Madder has been cultivated as a dyestuff since antiquity in central Asia and Egypt, where it was grown as early as 1500 BC. Cloth dyed with madder root pigment was found in the tomb of the Pharaoh Tutankhamun . Madder was widely used as a dye in Western Europe in the Late Medieval centuries. In 17th century England, alizarin was used as a red dye for the clothing of the parliamentary New Model Army. The distinctive red color would continue to be worn for centuries. By 1804, a dye maker in Britain had refined a technique to make lake madder by treating it with alum, and an alkali, that converts the water-soluble madder extract into a solid, insoluble pigment. This resulting madder lake has a longer-lasting color, and can be used more efficaciously. Alizarin changes color depending on the pH of the solution it is in, thereby making it a pH indicator.
Alizarin is the main ingredient for the manufacture of the madder lake pigments known to painters as Rose madder and Alizarin crimson. Alizarin in the most common usage of the term has a deep red color. A notable use of alizarin in modern times is as a staining agent in biological research because it stains free calcium and certain calcium compounds a red or light purple color. Alizarin continues to be used commercially as a red textile dye, but to a lesser extent than 100 years ago.