Recreating medieval blue ink

Ancient Origins has a post today about research in Portugal into the extraction of folium, a blue ink derived from a plant source and used in medieval illuminated manuscripts. Following and interpreting an historic text it has been possible to produce once again a pigment last produced in the nineteenth century. The post includes a video from the National Gallery about other blue pigments of the past - the most expensive being, of course, lapis lazuli or ultramarine, but also azurite and the later development of Prussian Blue in the early nineteenth century.

The post can be seen here