Monday 20 July 2020

Tracing the Potter's Wheel! A Panoply Interview with Dr Jill Hilditch

In this latest interview we're delighted to be speaking to Dr Jill Hilditch, Associate Professor of Archaeology at the University of Amsterdam. We're getting super up close with pots! Dr Hilditch is the Principle Investigator on a research project at the Amsterdam Centre for Ancient Studies and Archaeology (ACASA): Tracing the Potter's Wheel. Investigating Technological Trajectories and Cultural Encounters in the Bronze Age Aegean (2500-1200BCE) You're in for a fascinating read finding out how archaeologists go about their analysis of the world of pots...

1) How can an archaeologist tell where a pot came from?
Whether it’s your favourite tea mug or a 5000 year old wine goblet in a museum, all ceramic pots are essentially made from clay and water (with a few occasional additives!). These clays are the naturally occurring weathering products of many different types of rocks and sediments, and it's this link to the geological environment that allows us to study where a pot came from. We use microscopic and elemental analysis techniques developed within geology to identify the tiny bits of weathered rock and minerals within the ceramic paste and try to see if these components match the geological environment where the pot was found. By establishing local compatibility with the sediments and rocks at a site, we have a solid basis for making our interpretations on whether that pot was made locally or was imported. Finding out where potential imports come from relies upon finding a suitable match with published ceramic fabrics from other sites. Of course, humans always complicate things and making a clay paste suitable for producing a pot often means altering the geological sediment. This can be done either by adding temper to the clay, or fining the natural clay through crushing, sieving or water settling (levigation). All these human behaviours affect the appearance and contents of a ceramic fabric but, luckily, we’ve also got quite good at identifying these important behaviours in the manufacturing process!

Above, Jill getting stuck into some microscopic analysis.

2) How did people make pots before the invention of the potter's wheel and what is it that the wheel offers that tempted potters to make the switch?
Before the wheel, ceramic pots were built by hand. Perhaps the most ‘low-tech’ method of all is the pinch method, where a potter takes a lump of clay, makes an indentation with their thumb and then uses a pinching motion with their thumb and forefinger to push the clay into the desired form. Several other hand building methods use this pressure principle but achieve it with a range of different tools, such as paddles and anvils, or you can shape or mold the vessels around other pots to create similar shapes or standardise the size of the pots. One of the most common hand building techniques we see in prehistory is coiling, where coils or snakes of clay are rolled out and then stacked on top of each other to build the pot. These coils are then joined together by pinching before being smoothed to create the wall.

Studies by Valentine Roux and colleagues working on the Near East from the 6th and 5th millennia BCE show that the use of a rotating device for potting first appears in combination with coils. This use of rotative kinetic energy (RKE) would have helped with the addition of coils, as well as the thinning and shaping of the walls of the vessel, allowing the potter to be stationary rather than ‘orbiting’ the vessel. This is why we refer to early pots as ‘wheel-fashioned’ because the invention of the potter’s wheel did not go hand-in-hand with the innovation of wheel-throwing: the first use of rotating devices was not to ‘throw’ a pot from a solid lump of clay but to help fashion or finish a coiled rough-out of a vessel. The rough-out was placed onto a wheel head (those that have survived in the archaeological record are made from stone or fired clay) which could rotate in a socket in the ground or a raised pivot. Unfortunately, there is scant material evidence for most of the devices used for potting in the past, probably because many of the components for the wheel device were made of wood and other organic materials that have not survived in the material record.

Above, Dr Caroline Jeffra from Tracing the Potter's Wheel transforming coils into pot ( )

So, we're left with an interesting puzzle – why did potters switch from hand building to wheel-fashioning techniques and how did the innovation of wheel-throwing emerge from these beginnings? A common argument is efficiency: simply put, the potter’s wheel allows potters to produce more vessels in a shorter timeframe than hand building techniques, thereby laying the foundation for increased production levels and labour specialisation. This is perhaps true for wheel-throwing, but the use of a wheel to fashion or finish a coil-built rough-out is remarkably difficult and would have, initially at least, represented a greater investment of time for skill acquisition and tool creation by the potter. There is also an argument that the wheel afforded the production of better-quality vessels too, though anyone who has ever seen the eggshell-thin vessels of Kamares Ware alongside the crudest of wheel-coiled conical cups on Crete may disagree! Our project decided that it was perhaps a good idea to investigate which shapes were made using the wheel, as well as which wheel-based method and by whom (were these locally trained or itinerant potters?), in order to shed new light on this puzzle.

3) Your project is examining the transmission of knowledge of the potter's wheel – how was knowledge of the potter's wheel transmitted?
Our Tracing the Potter’s Wheel (TPW) project focuses on the use of the potter’s wheel within the forming stage of the ceramic production sequence. This sequence, known as the chaîne opératoire, is used by archaeologists to consider the choices (deliberate or unconscious) made by the potter throughout the entire manufacturing process. The chaîne opératoire goes from raw material sourcing and processing to create a suitable paste, through to the forming technique, the surface treatments applied to the formed pot, and the final firing process. The choices made by a potter are a window into their social and cultural context, as the gestures, skills and know-how the potter needs are learned by watching, copying, and participating with their peers in the production process. This group is called a community of practice and they are identified through the similarities in the production sequence, which are materialised in the pots they produce. Archaeologists are becoming increasingly aware that these shared practice-through-knowledge groups can be traced in the material record, opening up new possibilities for tracing technologies such as the potter’s wheel.

Above, a charming example of Minoan pottery.

Some of this know-how is easier to learn than others; for instance, decorative styles can be transferred by simply watching another potter at work, or even recreated from seeing one of their finished pots. For the forming stage this is often a much harder process: not only is the method of making the pot invisible in the finished vessel but so are necessary physical gestures and the tool-kit too. For this reason, the transmission of the potter’s wheel is one of the surest indicators we have for potting specialists interacting with one another for sustained periods of time. This is why it is so crucial to determine if a wheel-made pot was produced locally, or simply imported from another production unit, because we need to establish if a person with that skill-set was working at the site where the vessel was found. If we are ever to explore how the wheel emerged as a technological innovation, and how it spread between these communities of practice through time, then we need a clearer understanding of who was using it, where and in what way.

Above, Minoan pottery with bonus octopus.

In the case of the Bronze Age Aegean, the appearance of the wheel was considered as two potentially independent events, connected to two different horizons of intensifying cultural contact. The earliest identified horizon of wheel use appears during the later Early Bronze (EB) II period (c. 2500-2100BCE), known as the Lefkandi I/Kastri phase, widely thought to indicate increased trade in metals between social groups in the Aegean and (predominantly) western Anatolia, where the potter’s wheel is known to have already been in use. In the later transition, from the Middle Bronze (MB) to the Late Bronze (LB) period (1800-1600BC), the potter’s wheel is considered as a technology of the Minoan culture of Crete, spreading beyond the shores of Crete as part of a package of technologies indicating growing Minoan power and influence, the so-called ‘Minoanization’ of the southern and central Aegean region. Our project has recently reassessed diagnostic traces of wheel use within late MB and early LB Cretan, and non-Cretan but ‘Minoanized’ ceramic assemblages (collections of ceramics found at the same site) – we've shown that the combination wheel-coiling technique continues to dominate the ceramic record. This would indicate that wheel-throwing is necessarily a later technological development than LB I within the Aegean. This transition from wheel-coiling to wheel-throwing remains poorly understood in Aegean archaeology and beyond, yet is critical for investigating how knowledge of the potter’s wheel was transmitted between communities of practice.

Above, Jill introduces the project in a short video.

4) What approaches have you taken to find that out?
The TPW project has brought together an experimental archaeologist (Dr Caroline Jeffra), a digital archaeologist (Loes Opgenhaffen) and me, a ceramic fabric specialist, to investigate the transmission of the potter’s wheel in the Bronze Age Aegean. Caroline has carried out a systematic programme of experiments to explore the macrotrace evidence for wheel-coiling and wheel-throwing in the Bronze Age Aegean. She designed and produced a ceramic type set to improve our ability to differentiate between these two specific wheel use strategies and then applied the results to the study of archaeological ceramics from the Bronze Age Aegean. This enabled her to establish the range of diagnostic traces associated with each specific wheel-forming technique. Using a Dino-Lite digital microscope, I recorded the ceramic fabrics of the wheel-made vessels (identified by Caroline) to determine which vessels were compatible with local production and which were imported to the site under study. Loes has also been busy using a DAVID structured light scanner to make 3D models of the experimental pottery typeset and reproducing some of these vessels in macro form through 3D printing to serve as teaching aids. Loes’s 3D models, alongside Caroline’s macrophotographs of wheel traces and production videos of the experimental pots, as well as my fabric photomicrographs, form the core of our dataset that we want to share with other archaeologists interested in studying the potter’s wheel.

Above, Caroline Jeffra (l) and Loes Opgenhaffen (r) at work on Tracing the Potter's Wheel.

Sharing really is the key word here because we quickly realised that no single research team would be able to generate enough data within the timeframe of a government-funded project to fully understand the trajectory of the wheel in the Bronze Age Aegean. Faced with such a dilemma, we decided to focus our efforts on creating a tool-kit for other archaeologists so that they could generate their own datasets and contribute to a collaborative effort to address this large question of the potter’s wheel. We're going to publish instructions for our methods, and user manuals for the equipment we have used, to ensure compatibility of results generated by different individuals and teams in different places. In this way, we want to start a crowd-sourcing effort to solve the potter’s wheel puzzle.

Above, Minoan pottery from Akrotiri on Santorini once again showing command of shape and a flair for decoration featuring the natural world.

5) Tell us a bit about how your research is being visualised.
One of our main goals is to produce an open-access digital resource that enables other archaeologists to use our visual data, not only for learning how to recognise wheel traces but also guidelines on how to produce their own visual datasets which can then be uploaded and shared. As none of our team are database experts, and our data is so visual in nature (and also large in size!), we are working with a data consultancy team to build our own tailor-made digital data platform. We've already generated massive amounts of photographs of the archaeological pots we're studying, as well as production videos, 3D models, and more photographs of the project’s experimental pots. If we manage to secure the appropriate permits from the Greek Ministry of Culture, we also hope to supplement our platform with 3D models of key archaeological vessels, to highlight the challenges in spotting and interpreting macrotrace and ceramic fabric information, and to create a useful research resource for everyone interested in the potter’s wheel.

For now, we've been posting our annotated 3D models of the experimental pots on SketchFab , as well as discussing many methodological aspects of our techniques on our project website. Last autumn we were invited to take part in the Heraklion Museum’s Daedalus exhibition, which focused on the technologies associated with this mythical craftsperson, including the potter’s wheel. Our team designed a series of installations exploring the visual aspects of our techniques and created a hands-on touch table filled with experimental pots and 3D printed replicas to allow museum visitors to engage with our research. Without a doubt, it was one of the hardest but most rewarding experiences I’ve ever had, both as a team member on the TPW project and as an archaeologist – after all, who puts on an interactive exhibition with no archaeological material in possibly the best archaeological museum in Greece?!

Above, Tracing the Potter's Wheel at the Heraklion Museum’s Daedalus exhibition.

6) You've done some fascinating jobs in some interesting places. Could you tell us a bit about that and about what subjects you'd recommend for people interested in getting into archaeology?
I started off with a joint degree in archaeology and geology and soon found that ceramics were the perfect mix of both fields. It also helped that ceramic petrography (laboratory-based microscopic analysis of ceramics) was a valuable skill to have, as I could work in any period and region that had ceramic objects as part of the archaeological record. For my PhD I worked on ceramics from the amazing prehistoric settlement of Akrotiri on Santorini, a site with an unbelievably rich material record preserved by metres of volcanic ash (think Pompeii but 1500 years earlier). I've also been privileged to take part in the excavations and surveys of the island of Keros and the major Early Bronze Age settlement and maritime sanctuary of Dhaskalio-Kavos. Since 2006 I have been trying to work out where all the pottery on that tiny marble islet came from and it remains one of the most important and enigmatic sites in the Aegean. Working at so many projects over the years has given me an enviable perspective on the ceramic fabrics of the Cyclades and my mobility as a researcher (hello Greece, Canada, the Netherlands, the UK and then finally back to the Netherlands again) has meant that I've rarely struggled to find research projects, for which I count myself extremely lucky. I can already hear several colleagues thinking loudly about where the results of some of those projects are, but it will all come out eventually, I hope!

Above, Jill checks ceramic finds at Akrotiri on Santorini in Greece.

For those wishing to enter archaeology today, it is difficult to offer a one-size-fits-all solution. There's no doubt that modern archaeology straddles the sciences and humanities fields, which means from social science, anthropology, classics, linguistics and sociology to materials science, biology, ecology and chemistry, not to mention computing technology and heritage studies – there's a path into archaeology for almost anyone! The best archaeological science is undertaken by those who not only understand the potential and limitations of their techniques, but can also anchor their methodology within archaeological theory, which means studying archaeology at university should be considered as an option by anyone interested in the field. Commercial archaeology is also growing in a number of countries to supplement local and national government sanctioned work. In some cases those companies offer valuable on-the-job training and support those who'd like to supplement their skills with further and higher education archaeology courses. Maybe as a university lecturer I'll always see the value of this environment for awakening curiosity and developing systematic research skills. Did I also mention that most Dutch universities teach in English and are substantially cheaper to attend than some UK universities?

7) What's your favourite ancient Aegean artefact?
Besides pots?! Hmm, this is too difficult to answer definitively so I’ll mention an object category I’m excited about at the moment – textile loomweights made from clay. Some of these objects occasionally look like owls, snakes or smiley faces (especially the discoid ones) but where they really interest me is their composition, of course! Weaving and textile production has long been assumed to be a locally-based domestic industry in prehistory, yet if we study these objects from a ceramic fabric perspective, we can see that they, like pots, have been made in different places, from different clay pastes, and were moving with people across the prehistoric landscape. I had exciting plans to work with a good friend and colleague, Joanne Cutler, on her ideas about textile worker mobility in the Bronze Age Aegean but sadly she passed away a couple of years ago and those plans were postponed. Needless to say, I’m looking forward to picking up this thread again (pun intended) with other colleagues in the future and showing the importance of Jo’s work in this area.

Above, a collection of ceramic loomweights from Late Minoan Crete (c.1600-1200BCE).

Many thanks to Dr Hilditch for sharing these insights into how ceramic analysis is done and how it can illuminate wider social behaviours. It's also been inspiring to see how the Tracing the Potter's Wheel is combining different expertise and creating resources that will enrich the whole archaeological community. Below you'll find some short videos by Tracing the Potter's Wheel featuring pots being made, an introduction to petrographic analysis, and a presentation by Dr Hilditch describing the work of the project in a bit more detail. You might also enjoy visiting the Tracing the Potter's Wheel blog , which features all sorts of interesting discussions, including Why Do Archaeologists Study Pottery?.

Above, throwing a pyxis pot.

Above, Petrographic analysis explained.

Above, a short talk in which Dr Jill Hilditch introduces the exhibition 'Tracing the Conical Cup' at the Netherlands Institute at Athens.

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