Aug 21 2014

Casting a medieval aquamanile

Bastian Asmus

Foundry: Medieval bronze casting of an aquamanile in a lost wax loam mould – by Dr. Bastian Asmus

The casting of an aquamanile in original medieval technique has been a long term intention of mine. A year ago I made an aquamanile in the form of a lion that dated to the medieval period, however I did not have time to cast that particular aquamanile in a technique that can be considered medieval.- The model however was made with the techniques known to medieval artificers.  It was made according to Theophilus Presbyter’s description in his schedula diversarum artium , a 12th century manuscript on artisan’s techniques. Theophilus’ chapter 61 on the making of the cast incense burners provides all the necessary information, with which an informed reader can go ahead an produce a formidable bronze (or any other copper alloy) casting. This information was used to prepare the mould for the casting of this aquamanile. There will be an article shortly on how to make the mould.

Reconstruction of a medieval loam mould for an aquamanaile in the form of a lion.

Loam mould of the lion aquamanile. The loam mould consists of the same ingredients as medieval moulds.

Casting a medieval aquamanile

The mould was prepared from  loam and made three days before the casting. The wax model was molten from the loam mould over embers. The mould was subsequently fired with charcoal. The charcoal was allowed to burn down to the top of the mould and before it was charged again with fresh charcoal. This was repeated three time s, just as Theophilus tells us . The casting was accomplished through the feet; so the mould is placed upside down for the casting. It was cast with a quaternary alloy of copper, zinc, tin and lead. The alloy is CuZn13Sn8Pb2 and was prepared for the casting.

References


Aug 11 2014

Peter Vischer the Elder, famous sculptor and Meister Rothschmied

Bastian Asmus




Peter Vischer (1455-1529) from the shrine of Saint Sebald, Nuremberg.

Details of a second cast of a self-portrait of Peter Vischer (1455-1529) from the shrine of Saint Sebald, Nuremberg. Original size of head: 6 cm.

I know the title says Peter Vischer the Elder, however this is a post on one piece of his work only: namely the self portrait of Peter Vischer. When I returned from a fantastic conference on Medieval Copper, Bronze and Brass in Dinant and Namur, Belgium,  I remembered that back in the nineties I had to make journeyman’s piece towards the end of my apprenticeship as an artistic bronze founder. This journeyman’s piece is the self portrait of Peter Vischer the Elder, the other two where portrait medals of Martin Luther and Albrecht Dürer, cast in a specialised medal casting technique. The self-portrait of Vischer is located at the front end of the shrine of Saint Sebald. The shrine was commissioned in 1499 and was finished in 1519. Peter Vischer the Elder was granted the title of  a master in the Rothschmied Handwerk in 1489. The Rotschmied or Rotgießer could be literally translated as red smith or red caster. Although the name would suggest the Rotgießer were obliged to work with red metals, such as copper and  copper-tin alloys only, or the Gelbgießer was obliged to work only with yellow metal, i.e. brass, this was not so: Many Rotgießer were working with brass and/or red brass as well. There was a distinction between the Rot- and the Gelbgießer, though and that had to do with the preferred moulding material: Rotgießer were working with moulding loam and Gelbgießer with moulding sand . Red casters were also casting larger objects than the Gelbgießer. It is most likely that there was no clear cut boundary between the two casting trades.

The self-portrait of Peter Vischer the Elder

Selbstbildnis des Peter Vischer (1455-1529)Coming back to the self-portrait of Peter Vischer the Elder: Here I show a few aspects of the raw cast and explain why this piece secured me the first prize in the competition of the chamber of handicrafts in Germany: The cast is near flawless. It was cast in one piece in the lost wax technique. There are only four core supports, two of which are the nails seen in the images. Self-portrait of Peter Vischer (1455-1529)The other two were placed in the top of the head and near the bottom of the hem at the backside. The gating system is attached in a manner as to leave the original surface fully intact. I left this piece in this state, because it shows the surface quality that can be achieved. The brownish colour stems from the various oxides of copper and tin, that develop upon contact with the moulding material and form a thin skin, which can be easily removed by ways of filing, scraping, or pickling.

References


Mar 6 2014

Course on prehistoric bronze casting

Bastian Asmus

BIld eines frisch gegossenen Bronzebeils

This is a hands-on experiential archaeology course in one of the most important Celtic hill-top fortifications in central Europe: The Heuneburg in south western Germany. On April 26/27 we are holding an intensive course on the archaeometallurgy of bronze with loads of information to go alongside the practical experience of casting bronze the ancient way.

It has been my main objectives to foster the first hand experience of metallurgical processes alongside the scientific study of past archaeometallurgical activities. Together with the Heuneburg Open Air Museum we are now busy  developing the Heuneburg Academy, where hands-on experience is thought of as an equally important aspect of archaeometallurgy, as is for example scientific archaeology or archaeology. Only through an transdisciplinary approach will we able to better understand our forebears.

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