“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.”
