Verdigris is an artificial pigment that dates from antiquity. Originally, it was produced by exposing copper to vinegar; nowadays acetic acid is used. It is acidic, so can contribute to the deterioration of paper supports. For this reason, it is more suited to oil or tempera painting than it is to watercolour. In tempera painting, it should be bound in animal glue or isinglass glue rather than egg york. When used in oil painting it should be held in a resin oil or balsam such as Venice Turpentine, as it can turn brown when ground directly into linseed oil. It is a fast-drying, transparent pigment, with a visible crystalline structure.
Larger quantities are available by request.
