If you can read German, that title tells you all you need to know. It's a recipe database for hand-written, medieval and early modern recipes for art supplies. (In German - sorry for those of you who don't read it). Most recipes are not only transcribed, but also translated, and there are search masks to hunt for specific ingredients or techniques - such as textile-related techniques. This is an ongoing work by Dr. Doris Oltrogge of the FH Cologne, and it's a brilliant idea.
Recipe database! Hooray!