Copper-based green glazes in a number of 16 th C. paintings were studied. No resin or only traces were found in several instances indicating that no copper resinate was used. This corresponds to findings from treatises and handbooks. Discoloured glazes often also contained chalk. This may be associated with the original presence of yellow lakes.The presence of basic copper chlorides and sulphates is explained as remains of contaminants in verdigris.

CNRS Editions
J. Goupy , J.-P. Mohen

van den Berg, K.-J., van Eikema Hommes, M. H., Groen, K. M., Boon, J. J., & Berrie, B. H. (2000). On copper green glazes in paintings. In J. Goupy & J.-P. Mohen (Eds.), Art et Chimie, la Couleur: Actes du congrès (pp. 18–23).