Experimenting with various soap ingredients is part of what makes soap making so much fun. In addition to scent and shape, adding color to soapy creations gives your product personality and flair. Luckily there are plenty of colorants to choose from, including LabColors, pigments, micas and natural colorants such as clays. If you prefer to use natural colorants, madder root powder is a great orange-red colorant option for both cold process and melt and pour soap.
A plant species in the genus Rubia, madder (INCI: Rubia tinctorum) is a climbing plant with small flowers and long roots. Madder root has been used for centuries as a dye for textiles and cosmetic products. Traces of madder have even been discovered in the tomb of the Pharoah Tutankhamun and in the ruins of Pompeii. The FDA requires approved cosmetic colorants to be used when specifically coloring cosmetics. Because madder root has not been approved as a cosmetic colorant, it should be used in soap for its herbal properties and not its inherent coloring ability. Madder root is considered not safe for infant products so do not use madder root with baby products.
Rubia tinctorum contains the organic compound alizarin, which give the roots their deep red color. Alizarin is also used to create madder lake pigments, which are sometimes referred to as rose madder and alizarin crimson. Madder lake has been used for centuries by painters to give their pieces rich red tones. In 1869, alizarin became the first natural pigment to be duplicated synthetically.