Previously in our blog we heard from Professor Bill Sillar - Professor of Archaeology and Technology in Society at UCL Institute of Archaeology, about the Roman Kiln UCL built at the farm. Below Bill describes the process of firing the Kiln for the first time during UCL’s ‘Archaeotech’ experimental archaeology course.
In September 2022 the UCL team returned to fire up the replica Roman Kiln they built in April.
Constructing the Roman kiln in April 2022
The kiln, based on an early second-century Roman kiln on the banks of the River Medway, originally excavated in 1975 by the Upchurch Archaeology Research Group (UARG). By September our replica kiln was dry to the touch, but still had a lot of moisture in the clay, so we started with a small fire at the base of the chamber to dry out and warm the kiln structure. We then placed our pre-prepared pedestals and kiln bars and continued to heat the structure.
A couple of the kiln bars broke, probably as we heated them up too quickly to release the moisture in the clay. We had made a few pots on the kick wheel we brought from Fishbourne Roman Palace, but, as with the original kiln assemblage, we made the majority of our pottery using hand building techniques, including a range of jars of similar sizes to those found in the excavated kiln.
The first firing of the kiln
So, we loaded the kiln placing the jars and other pots mouth downwards, we put two layers of pottery with a mixture of vessels. We continued to slowly heat the kiln. For fuel we were using coppiced wood from fences and structures that had been dismantled at Butser, this was predominately hazel that was aged and fairly dry, so a very suitable fuel to use in the restricted opening of the kiln flue. As the pottery began to heat up we placed a covering of pottery sherds (including some fragments of original Roman tiles) over the kiln load. (An interesting question is whether some of the pottery excavated at the original Medway kiln was being used as a sherd covering for the firing.)
The firing continues into the night
The results of the first firing
We kept the firing going into the night reaching a temperature of around 860 centigrade, and then left it to cool before unloading the following morning. This first firing was fairly successful with only 3 vessels completely shattered, but the pottery was slightly underfired and some large vessels had small cracks or chips, which were probably a result of production and handling faults. About 20% of vessels were partially reduced/carbonised as a result of poor circulation of air/oxygen during the firing.
The second firing of the kiln
Results of the second firing
A second firing was more successful reaching a temperature of 960 degrees, but again with about 20% of the pottery partially reduced/carbonised. We now intend to undertake further analysis of the original assemblage from the Medway kiln to consider how our improved understanding of the kiln might help our interpretation and we hope to undertake further firings to assess how different fuels and methods of covering influence the firing conditions.
Thank you very much to Bill and all the staff and students from UCL and Archaeology South East for building and firing this fantastic kiln here at Butser . We are looking forward to the next experiments!