Dear Richard,
As one involved in the Nahal Mishmar experiments with
Sariel Shalev and with Rungwe Kindon of Pangolin Editions
sculpture foundry (www.pangolin-editions.com/). The method
of investing the wax models was based on close inspection
of the original castings in the Israel Museum by Rungwe,
also bearing in mind likely ceramic technology at the start
of the 4th millennium BC. We thought that applying a slip
first was unlikely and it turned out to be unnecessary. The
first attempt at a ceramic was to use clay, sand to make it
refractory, tempered with chopped straw. This was a mistake
as the As-Cu-Sb alloys used have very low viscosity indeed
and filled every impression left in the mould matrix by a
burnt fragment of straw. The next stage was to use straw
processed through a horse and the use of horse manure in
the mix rather than straw gave very good results and, on
occasion, we could get a good surface finish. The problem
in finishing is the that the cast alloy is pretty hard and
polishing it gets pretty tedious. If you look at the
originals (for which no moulds survive so you have to work
from the objects) you will see that some objects like the
mace-heads have a good polish whereas some others seem to
have had much less finishing.
If you visit the Ashmolean Museum in oxford (the world's
oldest public museum) you can find an exhibit of these
experiments.
Yours,
Peter Northover
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Peter Northover
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