Alkanet Root is used as a natural dye in cold process soap making. There are different methods of infusing the root, it can be infused in an oil which would be part of your recipe or added to the water element of the soap. It offers colours that will vary depending on your other ingredients, from a pale mauve to a deep purple. The colour will eventually fade in the soap if left in direct sunlight.
Alkanet is also used as a natural wood stain and for dying wool.
MSDS Alkanet Root