Madder was distilled from Rubia tinctorum , a plant found in Turkey and the British West Indies. Its main coloring component was alizarin, and it was used to dye cellulose products. Mordants were used to help seal the color into the fabric and preventing fading. Indigo is a blue colorant of vegetable origin that was obtained from Indigofera tinctoria in India. The plant contains indoxyl, which oxidizes with the air when it s fermented to produce the dye.
Indigo is insoluble in water, which made for excellent fastness.
Indigo could also be obtained from certain snails, such as the murex. Before the introduction of Indigo, Europe had previously used woad to produce blue dye. They obtained the saffron lily from the hillsides of Crete. When the stamens were simmered, they produced an orange broth which dyed wool bright yellow. To prevent the dye from washing out, an alum mordant had to be used to seal the color fastness into the cloth.