Opening up my field notes to begin writing this report I was immediately transported to the site of my first kiln build. The pages of my note-book are laced with the smell of the wood smoke produced as the kiln was stoked and immediately I am back inlush green Wales, it’s early August and I am standing in a two sided garage which is
acting both as a wind tunnel and shelter depending on which way the rain is falling. I am taking a kiln building course in order to prepare for the replica Julfar kiln build due to take place in Ras al Khaimah (RAK) within the next few months. Joe Finch, amaster potter and expert kiln builder, is tutoring me and together we are building our first updraft kiln.
Ancient updraft kilns, sometimes termed as the first true ceramic kilns, are cylindrical in shape with an open top. The firebox is situated directly underneath the pots, which are stacked on top of each other on a perforated arched platform and covered with stones and shards to create a domed insulating roof. This type of kiln has been attributed to an ancient Muslim design dating back to antiquity and was used throughout Egypt, Iran and India and has been identified as the kiln type used to produce Julfar ware in RAK.
The valleys situated to the north east of RAK city are dotted with examples of such updraft kilns in various states of ruin. The best preserved at Wadi Haqil represent the end of a long and more or less continuous tradition of pottery manufacture inRAK that started in the 12th century and unfortunately came to an end in the mid20th century.
The updraft kiln Joe and I built does not visually resemble the one described above but does replicate the technology used. Made with thermalite blocks and household bricks we created a checkered arched platform above a firebox and built up the sides to contain the pots. The key questions I wanted to attempt to answer by building and firing the sample kiln were would the kiln work, how quickly would the temperature rise and could we control it, what sort of temperature could be achieved and would it have been possible, as my research suggests for the Julfar potters to only use ishbaq, (euphorbia larica) a desert shrub, as a fuel source?
In the absence of prepared pots Joe and I used over 90 glass bottles to pack and test
the kiln. It was important that the kiln was full to capacity in order to create an even temperature and true firing environment. We covered the top of the kiln with broken bricks and vermiculite to retain as much heat as possible, introduced apyrometer into the kiln to accurately measure the temperature and after a full day of experimenting and building, lit the firebox.
The temperature rose immediately and we began the process of stoking the kiln withwood and anxiously watching the pyrometer urging it to continue to rise. However as with all experiments it was not straight forward, after 2 hours we realized by thecolour of the glow produced within the firebox, that the pyrometer was not functioning properly and the temperature was significantly higher than was shown. Unfortunately, not until the kiln was cold and unpacked the next day would it be possible to ascertain what temperature may have been achieved.
Removing the layers of insulating material from the top of the kiln the following day was a tense process. The photographs that illustrate this report show that the glass bottles had bent and glass had begun to drip and run through the arched platform. Glass bends at 593C and begins to drip at above 700C, confirming that within 3hours the kiln achieved a temperature of 700C. High enough to transform clay into pottery and a good indication that with continued stoking a temperature of 1000C would be possible.
Without chemical analyses of sherds of Julfar ware it is impossible to be certain of the exact temperature(s) achieved by the Julfar kilns, and of course temperatures may have varied over time, but with close inspection of the porosity of Late Phase sherds and a clink test it is possible to estimate that a temperature range of between900C and 1000C is likely and through the construction of Updraft One, revealed to
be possible to achieve in a Julfar kiln type.
The process of constructing and firing the replica stone Julfar kiln, Updraft Two, is planned for early November. Joe Finch has agreed to travel to the UAE to support the build and I hope a build location in RAK will be confirmed in September. UpdraftTwo will be constructed from local stone and will attempt to replicate the Julfar design visually and technologically. It will be fired with a range of locally sourced fuel including ishbaq, wood and donkey and camel dung.
I am currently continuing to process and refine the raw clay from RAK and will begin conducting workshops using the local clay in September. It is estimated that 100pots will be required for the firing of Updraft Two and I will start creating this body of work as soon as the clay is mature.