Verdigris, coming from Old French and meaning green of Greece, is the bluey-green patina found on weathered copper. It was used as a pigment in medieval illuminations as it was the most vibrant green tone available, even though it is unstable as a water-based pigment. Its hue shifts from a blue-green to a bright green over several months. It also reacts badly with sulphur and lead pigments, eating through the substrate.

In chemistry terms, verdigris is copper acetate and is super easy to make with household chemicals. Take equal parts white vinegar (5% acetic acid) and hydrogen peroxide (3% solution) and mix in a glass container. You can do this with just vinegar but the peroxide speeds up the process from three months to 30 minutes by oxidizing the copper into the solution.

Heat up your mixture to about boiling. Remove from heat and drop in your copper. It should start bubbling immediately. Do this somewhere ventilated as I’m not sure what has is being released. The copper will dissolve an the solution will turn bluish.

When all the bubbling has stopped, pour your solution out into a large container so it makes a thin layer. Then place it somewhere warm to evaporate the liquid. Crystals should form which are copper acetate. Grind these up for pigment.

Verdigris | 2013 | ancient world, Art, How to, Middle Ages | Tags: , | Comments (0)

Leave a Reply

Your email address will not be published. Required fields are marked *