Today was our fourth day of excavation in the North Field trench. However, since we’ve had so many great posts on excavation so far (check out Garett’s and Cassandra’s posts on starting excavation and Elizabeth’s on the realities of excavation), I’m going to go in a slightly different direction today. One unique thing about our program at Vindolanda is the number of specialists we get to meet. In fact, over this past week we had a demonstration of experimental archaeology with the potter Graham Taylor, who was firing clay pots in a replica of a Roman kiln. I’ve interviewed Mr. Taylor about Roman pottery making and his career as an potter working with Roman techniques.
First, let’s briefly go over how Roman kilns worked. As you can see in the reconstruction below, they were built with thick walls of clay. These thick walls trap heat inside, and allow the combustion chamber to reach temperatures of 1100oC- although the temperature yesterday was only 900 oC. The walls themselves are reinforced with wood sticks inside the clay, and overtop you can see a temporary clay dome that is removed to get to the pottery inside. Roman kilns could also be built underground for even better insulation than just the clay alone. Ultimately, these types of kilns had a high success rate of around 90%, as they distributed the heat within evenly. Care, however, must be taken to increase and decrease the temperature slowly around 250 oC and 570 oC because of the silica in the clay, which rapidly expands and contracts at those temperatures in a thermal inversion and can crack the pottery (although the Roman wouldn’t have known the reason for this!)
This particular kiln at Vindolanda contains about 30-40 pots per firing. Building this kiln took 4 days, and this week was only it’s second firing, although it will likely be used at least once every two to three months. While it could be used more, the frequency of use at this site will be determined by whether there are enough pots to fill the kiln and justify firing it. (It uses an incredible amount of wood to reach the necessary temperatures. Can you make out the enormous wood pile in the picture above? Consider for a moment just how much fuel a Roman city would require between its various industries, heated homes, and bath houses.) The first firing of this kiln was primarily to dry the kiln out, as it was constructed from wet clay, and this week was its first firing for pottery. Below, you can see one finished black earthenware pot. (Earthenware refers to the temperature of firing, under 1150 oC, as opposed to stoneware and porcelain at temperatures above 1200 oC).
There’s some interesting science going on behind the colour of this pottery. It was created by starving the kiln of oxygen at the very end of the firing, by sealing up all the openings with clay. This creates reducing conditions, because the burning of the fuel that provides the heat for the kiln consumes all the oxygen that remains. With the depletion of oxygen, the iron oxides present in the clay are converted from an orange colour to a black colour. This needs to happen at the very end of the firing; if the kiln were starved of oxygen earlier in the firing, the lack of oxygen could prevent the rest of the fuel from igniting and keep the kiln from reaching its proper temperatures to turn the clay into pottery.
Such experimental archaeology obviously requires some research to guide the reconstructions. The sources Mr. Taylor primarily draws upon include excavation reports, visiting excavations in person, and museum store rooms for evidence on the types of pottery and its construction. This is a unique way to approach archaeology, and so I asked Mr. Taylor how he entered this field. Mr. Taylor is a potter by trade, although he has always been interested in archaeological techniques and incorporated aspects of the techniques into his own contemporary creations. About 15 years ago, he moved to experimental archaeology and reconstructions of archaeological works, which is what he has focused on since. He considers himself to be both an experimental archaeologist and a potter, rather than just one of those options. While the new kiln you’ve seen featured in my photographs today is at Vindolanda, Mr. Taylor has also worked a kiln at the fort Segedunum at Wallsend for much longer. (For those of you not familiar with detailed English geography, Wallsend is the modern town where Hadrian’s wall ends; you can see pictures in Aline’s post from last weekend). Finally, I asked my most difficult question of all: what his favourite reconstructed work was. After initially suggesting all of it since each piece was so different, he answered that some of his Bronze Age reconstruction works were his most recent favourites.
If you’re interested in Mr. Taylor’s works, I’ve included a link to the gallery portion of his website, where you can see images of the various works he has recreated, ranging from the Bronze Age to Roman to Cold War teacups for a museum gallery. http://www.pottedhistory.co.uk/Photo_Gallery.html
For me, the most interesting part of my experiences with Mr. Taylor was seeing the numerous ways one can approach and contribute to our understanding of history. As a student with academic experience in diverse areas including music, environmental science, and classical studies, it was enjoyable to see that when one specializes in a field distinct from archaeology and classical history, it is possible to continue to contribute to our understanding of history, and to apply this specialization in order to bring a unique perspective to history. I hope that in the future, I will be able to do this with my own studies.