Query: What would verdigris do to other colors that it came in contact with?
Context: It was used by the Romans in the murals of Pompeii, and in Celtic medieval manuscripts as early as the 5th century AD. It produced a blue-green which no other pigment could imitate, but it had drawbacks; it was unstable, it could not resist dampness, it did not mix well with other colors, it could ruin other colors with which it came into contact., and it was toxic. Leonardo da Vinci, in his treatise on painting, warned artists not to use it.