General term for a range of man-made copper-based greens of variable composition which have been in production since antiquity.
Formed as a result of the corrosion of copper when exposed to air, moisture and acid, verdigris is intrinsically unstable. In his handbook on painting materials and techniques, Il libro dell'arte, the early 15th-century artist Cennino Cennini writes that verdigris 'is beautiful to the eye, but it does not last.' However, its instability has been repeatedly outweighed by its beauty, and verdigris is commonly identified in manuscripts. Its corrosive properties are clear in the green strike-through often visible on the reverse of the page, where the pigment has begun to 'bleed' through the parchment.