- Chapter Sixteen -
spearheads and ornaments, was based on the use of bivalve ceramic moulds, as is
demonstrated by many flash lines round unfinished castings (Northover 1982). One
possible reason for this was that beeswax of sufficient quality was very scarce.
Although bee products are known from the Bronze Age, it is possible that they are
from wild or forest bees; some effort is required to refine beeswax from them, and
the product from the domesticated honeybee may have been seen as essential. It may
be coincidence but the earliest remains of honeybees from British sites are no earlier
than La Tene either.
The freedom of modelling given by the use of eire perdu investment casting
liberated the bronzesmith. Casting by means of piece moulds never achieved the
fantastic skill and three-dimensionality that it did, say, in China and it was only
the new technique that permitted anything similar. Initially the most complex shapes
were small, as in the fibulae, and larger, ornamental castings still tended to be
relatively two-dimensional. For small, flat items simple bivalve moulds, often of
stone, remained in use (e.g. Savory 1976: 104). One of the greatest expressions of this
is the openwork bronze castings designed to ornament a wooden jug from
Brno-Malomerice in former Czechoslovakia, a work so expressive of Celtic art that
part of it was used for the cover illustration of the catalogue for the great Celtic
exhibition in Venice in 1991 (Tanzi 1991; Meduna and PeSkar 1993). Lesser pieces,
such as highly complex armlets, appeared in many parts of the Celtic world and
continued to develop in areas as remote as Scotland until the second century AD ..
In Britain the most typical products of Celtic casting must be the many elements of
horse harness which allowed the smiths to show all their decorative skills.
Although the basic elements of the casting technique remained the same, the
technology did gradually evolve with time, sometimes in surprising ways. Crucibles
from about the fifth to third centuries Be were deep, narrow cups with a thick
handle; they were placed in the hearth with the draught directed at their base so the
exterior became heavily slagged while the charge was quite well protected from
oxidation. There was then a change to a shallow triangular type without a handle,
characteristic of the industry at Gussage All Saints already mentioned. Here the
draught was -directed at the rim of the crucible, which became heavily slagged.
Certainly it was possible to melt small charges of metal very quickly in this way but
this had to be balanced against the considerable losses of metal through oxidation.
From the first century Be new types, generally in the form of hemispherical
bowls with pouring lips, became standard in the south and gradually spread north-
wards over the next century or so. This slow spread is seen with some aspects of iron
technology as well and a series of isochrones can be drawn across Britain to chart the
adoption of several techniques. Moulds changed as well with developments in the
provision of runners and gates. The Gussage All Saints terret moulds from the late
second to early first centuries Be have a single runner serving a single terminal, while
those from Silchester of a century later have two, one for each terminal. The
Silchester moulds also show how multiple matrices were included in one mould
flask. Another odd feature at Silchester is that the matrix surfaces are not smooth
but have a ribbed pattern; the rough surface would only have increased the work of
finishing the casting unless it was designed to provide a substrate for some form
of cladding (Northover unpublished).