Brazilin is a re pigment obtained from the wood of the brazilwood family (Caesalpinia sp), and is also known as Natural red 24. Brazilin has been used since at least the middle ages to dye fabric, and has been used to make paints and inks as well. The specific color produced by the pigment depends on its manner of preparation: in an acidic solution brazilin will appear yellow, but in an alkaline preparation it will appear red. Brazilin is closely related to the blue-black dye haematoxylin, having one less hydroxyl group.