Gundestrup Cauldron - Metallurgy

Metallurgy

The Gundestrup cauldron is composed almost entirely of silver, but there is also a substantial amount of gold for the gilding, tin for the solder, and glass for the figures' eyes. According to experimental evidence, the materials for the vessel were not added at the same time, so the cauldron can be considered as the work of artisans over a span of several hundred years. The quality of the repairs to the cauldron, of which there are many, is inferior to the original craftsmanship.

In the time that the Gundestrup cauldron was created, silver was obtained through cupellation of lead/silver ores. By comparing the concentration of lead isotopes with the silverwork of other cultures, it can be suggested that the silver came from multiple ore deposits, mostly from Celtic north France and western Germany in the pre-Roman period. The lead isotope studies also indicate that the silver for manufacturing the plates was prepared by repeatedly melting ingots and/or scrap silver. Three to six distinct batches of recycled silver may have been utilized in the making of the vessel. Specifically, the circular "base plate" may have originated as a phalera, and it is commonly thought to have resided in the bottom of the bowl as a late addition, soldered in to repair a hole. By an alternative theory, this phalera was not initially part of the bowl, but instead formed part of the decorations of a wooden cover.

The gold can be sorted into two groups based on purity and separated by the concentrations of silver and copper. The less pure gilding, which is thicker, can be considered a later repair, as the thinner, purer inlay adheres better to the silver. The adherence of the overall gold is quite poor. The lack of mercury from the gold analysis suggests that a fire-gilding technique was not used on the Gundestrup cauldron. The gilding appears to have instead been made by mechanical means, explaining the function of closely spaced punch marks on the gilded areas.

An examination of lead isotopes similar to the one used on the silver was employed for the tin. Fortunately, all of the samples of tin soldering are consistent in lead-isotope composition as ingots from Cornwall. The tin used for soldering the plates and bowl together, as well as the glass eyes, is very uniform in its high purity.

Finally, the glass inlays of the Gundestrup cauldron have been determined through the use of X-ray fluorescence radiation to be of a soda-lime type composition. The glasses contained elements that can be attributed to calcareous sand and mineral soda, which are typical for the east coast of the Mediterranean region. The analyses also narrowed down the production time of the glass to between the second century BC and first century AD.