The most expensive of all was verdigris, which was made by hanging copper strips over a vat of horse dung and vinegar and then scraping off the oxidized copper that resulted. It is the same process that turns copper domes and statues green—just quicker and more commercial—and it made “the delicatest Grass-green in the world,” as one eighteenth-century admirer enthused. A room painted in verdigris always produced an appreciative “ah” in visitors.
