The technique I use is one that
was developed around the 3rd century BC. It was developed in
Europe and used by the Romans as well as Celtic tribes.
The ancient Celts would have
gouged out the metal to make space for enamel, or cast a piece
of metal using the lost wax method. I use the more modern
method of etching to create the same effect. This involves
preparing the copper by annealing and cleaning, and applying
the design with an etch resist.I make the resist myself by
combining asphaltum, beeswax and rosin. The asphaltum creates
a strong resist to the acid, the beeswax helps to keep it from
becoming brittle, and the rosin helps it to adhere to the
metal. The edges of the design must then be perfectly defined
with a scribe, as any flaws will be etched into the finished
piece. I use ferric chloride, a chemical salt, to etch the
copper. This solution is slower and safer than acid, and it
gives me more control.
first rough coat of resist
lines refined and second coat of resist
after being removed from the ferric chloride
resist removed with ammonia-ready for enamelling
I also employ a technique
called "bas taille", where some of the resist is
scratched off half way through the etching process, so that
two levels of etched design are created.
After the resist is applied,
the pieces are placed in a vat of ferric chloride solution
that is agitated with an air hose to keep the corrosive
particles moving evenly around the pieces. This process takes
anywhere from 20 to 30 hours. When the piece is ready, it is
placed in ammonia to remove the resist and the ferric residue.
It is again annealed and cleaned. The grains of enamel are wet
charged into the depressions with a small spoon, and fired
when dry.
Each piece is fired
approximately 5 to 7
times depending on the depth of the etch and the relative
hardness of the colours. All pieces are counter-enamelled for
stability and strength. The piece is then sanded, refired and
polished. The final steps are the application of a coat of
lacquer to prevent tarnishing and the addition of findings
where necessary. The entire process takes at least five days.
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