< HOT PATINATION
FUME PATINATION
A fume patina is imparted by exposing the cast to an atmosphere saturated with an active chemical vapour, or occasionally, a smoke particulate. The cast is normally sealed in a fume cupboard and a quantity of the colouring solution is left exposed in close proximity to the sculpture, thus allowing the evaporation of the chemical into the immediate atmosphere.
Chemically enriched air reacts with the cast alloy over a period of time, resulting in the development of a patina. After an appropriate time, the contained vapour is safely evacuated from the chamber and the cast removed. Still active compounds on the cast’s surface are neutralised by rinsing in clean de-ionised water, before finishing off with a protective wax coating.
The fume patina is especially well suited for use with volatile compounds which exhibit a strong tendency to evaporate in ambient conditions. For use on art and design works, the fume process is generally associated with AMMONIA based compounds – these tend to evolve a blue to black patina on most cast and wrought copper alloys.
Historically, burning straw in proximity to the cast, then fixing the resulting matt black deposit in a milk saturated media was a popular patination technique, which was still used by founders well into the early part of the last century, though this extended colouring technique is more or less redundant nowadays (see SUPPLEMENT).
BURIED & COVERED PATINATION >
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