Watercolor paint made from woad

Woad is a plant and a blue dye taken thereof, popularly associated with iron-age Britons but replaced by the superior Indigo plant long before the modern age. But it has its fans and now you can even buy watercolor paint made from it. Don't leave it out in the sun. [via]

The famous artist Lucas Reiner experimental widely with woad as a watercolor; one of his woad paintings is reproduced above.

This series of delicate watercolor studies include experimentation with woad, a subtle blue dye derived from an herb that grows wild in the British isles, which is said to have been used by the Celts since ancient times to color their faces and bodies before going into battle. While not as vibrant as indigo, the variety of tones produced by woad can be unpredictable to work with, yielding striking visual effects in the finished watercolors.