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.
|