Some Important Dyes

Both of the following dyes were sold in powder form and then mordanted with alum to form a lake.
There are three methods of mordanting:

Made from the roots of the common madder plant (Rubia Tinctoria)
Produces a bright red color:
Many civilizations have used rose madder, going back to Ancient Egypt and India, to produce rose-colored natural dyes.
The color index name used by paint and textile chemists is Natural Red 9 (NR9).
Was not used as a paint pigment in the Renaissance because it was considered a weak color.
In the 19th century, a synthetic form of Rose Madder, called Alizarin Crimson, was invented that was superior.

Made from the leaves and stems of the woad plant (Isatis Tinctoria)
The pigment in woad is the same pigment as that in indigo, although it is less concentrated.
Woad was the only source of blue dye until the end of the 16th century.
Julius Caesar reports in De Bello Gallico that the Britians colored their bodies with woad blue. They were known as the "painted ones."
A woad based pigment was used to illuminate the Lindisfarne Gospels.
For a time in the 12th century, the official color of royal robes in France was changed from cochineal red to woad blue. This greatly increased the demand for woad.

Indigo dye has a distictive blue color.
Obtained from a variety of sources, the primary commercial plant in Asia being Indigofera tinctoria.
Amoung the oldest dyes for textiles and printing.
Was a luxury item imported from India by Arab merchants.
Used in Ancient India, Mesopotamia, Egypt, Greece, Rome, Britian, and South America.
Was a rare commodity in Europe during the Middle Ages; woad was used instead.
In the late 15th century, increased global trade brought in indigo from India and South America.
Since indigo was a superior die to woad, it threatened the woad industry.
France and Germany outlawed indigo in the 16th century to protect the local woad industry.