Bronze casting

[Brochfael]

I'm working towards casting some bronze items and would like to talk about techniques with anyone else who has tried it.

I particularly need to know what kind of clay or clay/sand/otherstuff mix to make my moulds and crucible out of.

[Blackbird]

Never tried it, I'm afraid. Though I do own some lovely bronze Medieval rings which have obviously been made with lost wax casting.

Though it's probably not helpful, you might find this interesting:

From Lloyd and Jennifer Laing's book 'Celtic Britain and Ireland'...

"Casting.
The ingots were melted in small triangular crucibles, some lidded and some with handles, with were lifted with tongs. A serrated impression from tongs was visible on the outside of one of the crucibles from the Mote of Mark. Casting was done in clay two-piece moulds, which were produced by using a model or die to make an impression and which were then joined together and cased in clay.

A former (a piece of wood inserted to form a channel in the mould for the metal to flow in) of wood or some other material was used to make the ingate (entrance to the mould) and the two moulds were keyed together by impressing one with a knife point or sometimes by using wooden pegs. The moulds were set on edge for the process, and then broken to remove the casting.

Celtic metal objects tend to be flattish, and one half of the mould is usually much more deeply impressed than the other (back) portion. Bone pins were used as models in mould making at the Mote of Mark and Dunadd; a lead die was used in brooch making at Dinas Powys in North Wales, and there is a lead brooch-pin model from Clogher. There are several models for making hinged pins; of lead (eg from Dooey, Co Donegal) and of copper alloy (From Fenagh Crannog, Co. Galway), for instance. Lead was probably favoured because it was easy to carve.

An intricate die or design experiment was found at Birsay, Orkney, with a Durrow spiral triskele. Silver foils (pressblech) were stamped with metal dies. These are better known from Anglo Saxon England, but a Celtic design appears on a die from Louth in Lincolnshire, probably Northumbrian.

Tools for working fine metal have been found on a number of sites - tongs, shears, anvils, hammers and awls."

You probably know all that already - but it was interesting for me

[ank]

Don't know much, but have heard that for small items cuttlefish bone makes and excellent mould former, cut in half with the blank "impressed " between the two halves.

You probably knew this already though.

[dane]

Hi Broch,

white sand is good for casting bronze, but if your working in small sizes and quantities then Dutch sand or 'delft clay casting system' would be your best bet as it is a fine particle clay/sand (similar toriver silt) used for casting fine quality silver and gold jewellery.

this method would mean you are using a 'fine clay silt' to cast into, but is re-usable almost as many times as you can pour it back into your pot.