Medieval metal working at Berkeley

One focus of the current excavations in the trench is the uncovering of 15th century buildings at the west end of the trench. These buildings show little evidence of domestic use with their assemblages devoid of the usual cooking pots and other domestic items. They have instead been suggested as industrial buildings used for the working of metal, in other words a possible late medieval smith.
This appears to fit with a previous interpretation of the site being used for metal working. Back in 2009 a large rectilinear building (see figure 1) was uncovered that dated to the 16th century. After consideration it was suggested that due to the lack of domestic assemblages this building was a series of separate workshops. Previous students studying Archaeological Science, analysed the soil material surrounding a stone hearth found inside the building and found evidence of copper, lead and zinc among other metals.

Fig. 1: Rectangular workshops

Evidence of zinc found on the site along with copper resulted in the possible conclusion that the workshops were working with brass, which is an alloy of copper and zinc. Brass is desired for being a versatile material that can be cast into moulds or sheets, which can then be hammered into shape (Victoria and Albert Museum and webmaster, 2012). However, creating brass was more difficult as zinc turns into a gas at the same temperature needed to melt the copper (Ward, 2008). The workshops at Berkeley were more likely used for working with the alloyed brass rather than smelting the zinc and copper to produce the brass. There is also a possibility that bronze was being worked, suggested from the evidence of copper and lead residue in the soil around the hearth. While it would also need the addition of tin, bronze is a strong and durable metal but can also be moulded and can be used to capture the fine detail and decoration (Victoria and Albert Museum and webmaster, 2012).

The hearth (figure 2) was located in the far room within the building and had two distinct phases. The second phase (figure 3) was comprised of a layer of large stones arranged to form a small square, which had cracked due to the intense heat needed to work with the metals. The stones underneath this layer made up the original first phase of the hearth (figure 4) and consisted of smaller stones tightly packed again forming a small square. When these were finally lifted the clay beneath showed clear evidence of prolonged and intense burning at high temperatures.

Fig. 2: View of the hearth within the building.

The items that were being produced on site are unknown, however other sites have provided clues into the types of objects made by medieval blacksmiths. Items such as; weapons, repairs made to armour, iron workings but also more delicate items such as jewellery (Siteseen, 2014).

Fig. 3: Second phase of the hearth

The discovery of the medieval and post-medieval workshops on the site is not the first evidence of metal working at Berkeley. The team have identified evidence of Saxon lead working and Roman iron and copper workings possibly suggesting the site was an important metal working site through the ages, although at present we now very little about this. Hopefully next year more detail about metal working at Berkeley during the Roman period will be revealed as the feature producing the iron slag has only just begun being excavated.

Fig. 4: first phase of the hearth.

Bibliography:
Ward, G. (2008) The grove encyclopedia of materials & techniques in art: One-Volume format, New York, NY: Oxford University Press.
Victoria and Albert Museum and webmaster, D. M. (2012) 'Brass - Victoria and Albert Museum', available at http://www.vam.ac.uk/page/b/brass/, accessed 8 June 2016.
Siteseen (2014) 'Medieval blacksmith', available at http://www.medieval-life-and-times.info/medieval-life/medieval-blacksmith.htm, accessed 7 June 2016.

- Bethany Holland.