Making the Mercury sceptre

The reconstruction cameo for this programme was hosted by Andrew Lacey, a renowned sculptor, founder and specialist in archaeometallurgy. Andrew also produced the reconstruction Roman silver snake bracelet for the Warburton programme earlier in the 2007 series. The Time Team website caught up with Andrew to find out how he made the Roman sceptre.

What materials did you require for the sceptre at Godstone?
The sceptre was made from a wooden dowel, which was covered in thin brass strips held in place with iron or bronze pins. The handle and the figure of Mercury were cast in bronze from wax models.

What tools did you use and were they historically accurate?
The brass strips were embossed by pushing either wooden or metal tools into the surface. The figurehead of Mercury and the handle were cast in bronze but using the same method of making as the Warburton silver snake bracelet. All the methods used are historically accurate as time was taken in matching the evidence found on the artefacts to the reconstruction – also making sure that no material or techniques were more advanced than could have been used at the time.

What were the main steps in the process of making the sceptre?
First, the wooden dowel was cut and shaped. Then brass strips were punched and decorated using wooden and metal tools. These were twisted round the wood to cover it entirely, and held in place by small pins.

The handle and head of Mercury were formed as small versions first in sandy clay. These versions are called cores and are used to make the final cast hollow.

Onto these cores wax was modelled to make the finer version. Runners, vents and a funnel were attached to each piece and covered in more sandy clay to make the outer mould. The two moulds were dried and when all moisture was gone they were put in a fire to melt out all the wax. When this was done the moulds were taken out and propped up on the floor.

A crucible was put in the fire with bronze scraps in it and heated to 1050°C. This was later taken out using tongs, and the molten bronze poured into the moulds. Once cool the moulds were broken open and the castings removed.

At this point much work must be done to cut the runners, vent and funnel off and the surface of the metal polished up. Finally, the Mercury head and handle were secured to the wood with iron pins and a little pine resin.

What was the hardest part of the reconstruction?
The hardest part, as in the Warburton cameo, was drying the mould in wet conditions. The danger being that if the mould is not dry, when the molten bronze enters the mould moisture turns to steam and reacts violently. Therefore the mould can explode throwing all the molten metal into the air.

Would you change anything if you did the sceptre reconstruction again?
I would have liked to have done more work on embossing the brass strips, because it would have been interesting to have looked at the symbols used in the original Roman ones more closely.

Download a short mpeg video of the cameo (3Mbytes).

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