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We were discussing the Dorchester belt buckle and Late Roman belts buckles
generally at this evening's archeology lecture and the lecturer said that she though that chip carved were cast and the decoration carved into the metal. I always thought that the decorations were carved into a wax master that was then cast. Can anyone help me here- how were they made?

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Just as you say. Carved into the wax.
Thanks Christian - thats what I think on practical grounds. II'll need to give some more detail or sources- we agree, and what do you base your thoughts on?
you need to track half-fabricates or look at the backside of the items, when there is a rest of the deadhead. But also on grounds of production technique: Why spend hours upon hours carving this into metal, when you can do it easily into the wax? Especially, since the plates are cast, anyway? What would help are high-res pics. Normally you can see that a soft material was worked on and not the hard metal.
The idea that chip-carving involves cutting directly into the metal is a common mistake that is still replicated by people who should know better (David Wilson for one when he wrote about the St Ninian's Pictish hoard) and I think it's entirely the fault of the term itself which was originally restricted to the technique employed when carving this sort of design into wood.

These buckle elements (and other chi-carved metal itmes) are, of course, cast, any close up analysis of the surface of the metalwork will reveal that. However, I wouldn't be too quick to assume that the master model was made in wax. As the technique lends itself very readily to woodcarving, the master could easily be carved into wood which could be used as a stamp to create large numbers of casting moulds.
Alternatively, Morten Axboe did some work on the subject and concluded that there was no need for a master at all, and that the design was carved as a negative directly into the mould material.
(Axboe, Morten. "Positive and negative versions in the making of chipcarving ornaments." Festkrift til Thorleif Sjovold pa 70-ars-dagen. Oslo: Universitets Oldsaksamling. 1984. pp. 31-42.)
Chaps, you are stars. I'll try and locate the article on JSTOR- unless either of you have a pdf that you can email over?

I'm seeing the lecturer on Saturday and would like to get my facts in line!
I've got a hard copy of Axboe at home somewhere which I'll try to find. You should be able to source a copy of Barry Ager's "A LEAD MODEL FOR A LATE 5TH- OR EARLY 6TH-CENTURY SWORD-POMMEL" in Med Arch 50 (check ADS for a copy) which cites work done by E. Foltz, (‘Guß in verlorener Form mit Bleimodellen?’, Archäologisches Korrespondenzblatt, 10 (1980)) who experimented with different media and concluded that wood (probably box or yew) gave much crisper results than wax when creating models for chip-carved metalwork.

There's also this, taken from Coatsworth and Pinder's "The Art of the Anglo-Saxon Goldsmith" (Boydel 2002)

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I would agree with Medicus matt where there is mention of no master copy at times where the pattern is put into mold material.
A very good example of this can be found in re-enactment & re-construction page 2 that shows a beltplate put up for me by Byron Angel. This is where there is evidence of a sprue square in the centre rear of the plate and the three pins are formed on the back of the plate by being the vents for the bronze pouring.
This would have been a two piece mold with the decoration made in the lower half and the upper half having the sprue and vent holes, the decoration could well have been simply made by pressing into the lower clay mold them with this mold fire hardened your ready to make plates.
The reference I have given is early imperial belts by Magnus/Matt
I'm not very familiar with how the Romans cast their bronze, however what doesn't make sense is how thin the chip carved belt buckles are. When you compare other cast items, such as the propeller stiffeners of the same era the chip carved buckles are about 3 times thinner, and don't have a casting line on the back anywhere. The propeller stiffeners however do.

When you compare Raymond's Quite Press Chip carved reconstruction buckle, it is almost 3 times as thick as the original (which is about 1mm or less), with obvious casting lines.

The original also appears to have quite a uniform thickness throughout, much like hammered bronze would, with curled over edges (not solid). I would suspect the Romans would find it very difficult to cast such a uniform and thin design.....
I don't think it was so much of a difficult job casting thin pieces of equipment, for where I have given a reference about a beltplate there is also another photograph of a beltplate that I found and put into the BM.
The plate of that one is even less than a millimeter thick for with good lostwax casting one can come up with very good results.
It doesn't explain the lack of casting lines, which I would expect to be there. Also the anglo saxon brooches appear much thicker and deeper than the roman versions
Rado has achieved very good results casting complex items and obtaining a very thin
Thickness on them. Beltates, as Brian says, should have been a dwaddle!
I would think for a craftsman.
There are various types of casting and indeed different kinds of molds and some may leave casting lines where other methods don't
With modern lost wax casting one can use silicon as the medium for creating the wax copies, however these wax copies do have to have an investment mold produced and one can cast with the centrifical method or even a vacum casting method.
Therefore for casting lines it may all depend upon methods used.
I realize that today we can cast such thin items, but I wonder with the technology the Romans had whether it was possible then. They clearly didn't use Silicon or vacume casting Big Grin
If you used a chip-carved wooden master and stamped into a flat clay two part mould, I don't see why you couldn't cast very thin plates.

However, the majority of 'chip-carved' plates are a damned sight thicker than 1mm, otherwise they wouldn't be 'chip-carved', they'd be openwork. Wink
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