Medieval book historian Erik Kwakkel recently posted about this remarkable Dutch manual on watercolor painting from 1692. Entitled Treatise of Colors Used to Paint Water (a rough translation), the book was handwritten and colored by a fellow named A. Boogert during the tail end of Dutch Golden Age painting. It includes color swatches—rather like modern Pantone color swatches—and instructions on how to mix and dilute paints. The book is in the collection of Bibliothèque Méjanes in Aix-en-Provence, France. It can be viewed online at e-corpus.
images via e-corpus