Making Verdegris

Mistress Rohesia le Serjeant

 You need a small jar with a lid which has a pin-prick hole in it (you want excess gasses to escape but as little evaporation as possible).  Into the jar put a couple of coils of copper wire.  You can buy 1mm copper wire at a hardware shop and wind it around a pencil;  just make sure the copper hasn't been treated with any protective coating.  Add to this one stick of ordinary blackboard chalk broken into pieces, and enough plain vinegar to cover the lot.  Set the jar in a warm, even-temperatured place (such as next to a hot water cylinder) and leave for several months.  Once the vinegar has turned a deep emerald green, pour it off into a shell or saucer and leave it on a window sill to let the liquid evaporate.  You will be left with crystals of verdigris ready to grind and use with gum arabic as pigment (glair and verdigris don't work very well together).  You can refill the jar with vinegar and set it to brew again.

If the hole in your jar lid was too large or you left it too long and the jar has dried out, just add more vinegar and proceed as above.


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Authored by Jehan, Giles, and Yseult AS XXXVIII (2003)