Madder roots are obtained from the madder plant, scientifically known as Rubia tinctorum. These roots are most known for producing bright red dye. In the mid-19th century, however, this dye was replaced by a synthetic version. Madder root is also used for medicinal purposes.
Making a natural red dye is the most well known use for madder roots. The madder plant has been used to make madder red dye since ancient times. Cloth dyed with this root has been found in ancient Egyptian tombs as well as the lost city of Pompeii. Uniforms of British soldiers were also once dyed using madder root extract, earning them the nickname redcoats.
Several materials can be dyed using madder root dye, including cotton, wool, silk, and even leather. Dye produced from madder roots is typically a brilliant red color. The outside layers of the roots, which are brown, usually produce a muted shade of red. Inside layers, on the other hand, usually produce a more brilliant and refined shade of red.
One of the red pigments obtained from madder roots was called madder lake. To make this pigment, the dried roots of the madder plant are ground up and mixed with clay. This mixture is then treated with ammonia and alum.
Madder lake is a more permanent pigment than earlier dyes made from madder roots. The alum added to it is a mordant, which helps set the color. This dye usually lasts much longer, and can even be used to tint paints.
Chemists found that the chemical compound responsible for the bright red pigment was a substance called alizarin. This compound was only found in madder roots until 1868, when two German chemists were able to produce this compound from a coal tar. Since this was a much faster and easier way to obtain alizarin, madder roots were no longer necessary to produce the dye.
Today, individuals can still make a natural red dye from these roots. Madder root extract can be found in some art supply stores as well as on the Internet. Common madder can also be found growing wild in some parts of Europe.
Madder roots were also a common herbal remedy for liver and kidney problems. This was often steeped in wine or water to help alleviate jaundice, for example. Today, some individuals still use it to prevent kidney stones. Ingesting this plant can cause a person's urine to turn red, but this side effect is generally harmless.