British Museum blog

Conserving Dürer’s Triumphal Arch: photography and imaging

Ivor Kerslake, Photography and Imaging Manager, British Museum and Joanna Russell, Scientist, British Museum

Before any conservation treatment could commence, and with the Arch now out from behind its screen of glass for the first time in a generation, we were granted the opportunity to create a series of high-resolution images. The British Museum’s newly commissioned photographic studio was cleared for two days and Dürer’s masterpiece was expertly transported down the six flights of stairs and carefully unrolled in the main studio. Because of the fragility of the print we were unable to position the work vertically, which would have made our work considerably easier, so it was delicately unrolled on the floor. The challenge was then how to get high enough over the print to get it all within one shot. This was the first real test of the new facility. We decided to use a mobile extendable work platform (MEWP). Since the studio had been designed to enable access to and photography of large objects, we had sufficient space to manoeuvre.

Carefully unrolling the print ready for photography, with the mobile extendable work platform in place.

Carefully unrolling the print ready for photography, with the mobile extendable work platform in place.

Senior photographers, Kevin Lovelock and Saul Peckham used their skills to light the print to give an even and colour-balanced appearance, and also employed a raking light technique to highlight areas of special interest to both conservators and curators.

The print recto (front) in direct light.

The print recto (front) in direct light.

The print verso (back) in raking light

The print verso (back) in raking light.

Detail of cotton backing with embossed reversed '1515', the date in which the printing of the Arch commenced.

Detail of cotton backing with embossed reversed ‘1515’, the date in which the printing of the Arch commenced.

While the print was in the photographic studio, scientists Joanna Russell, Joanne Dyer and Antony Simpson took the opportunity to capture some detail shots using infrared and ultraviolet imaging.

Joanna Russell setting up the ultraviolet and infrared photography apparatus.

Joanna Russell setting up the ultraviolet and infrared photography apparatus.

Visible light is only a tiny part of the electromagnetic spectrum – beyond the red end of the visible spectrum is infrared radiation, and beyond the violet end is ultraviolet light. This non-visible radiation can also be recorded in images, by using special lights, cameras and filters. These imaging techniques may tell us more about the materials or construction of an object or artwork, depending on the ways the materials interact with the different wavelengths of light.

The ink used for the print absorbs infrared radiation, so appears clearly in these images, and is likely to be a carbon-based ink. However, an ink inscription becomes invisible in the infrared image, showing it is made using a different type of ink, probably iron gall ink.

TA_Pic_ed2

Left: A visible image of a detail from the Arch. Right: An infrared reflectogram of the same detail. The words ‘The Gate of the Nobility’ do not appear in the infrared image.

Ultraviolet light causes some materials to luminesce, that is to give off visible light. The ultraviolet-induced luminescence from the paper has a yellower appearance in one area of the detail shown below. This reveals that the scene in the bottom left of this detail is printed on a separate piece of paper to the surrounding areas.

Image showing an ultraviolet-induced luminescence detail. The scene in the lower left is printed on a paper with a more yellow luminescence than the surrounding areas.

Image showing an ultraviolet-induced luminescence detail. The scene in the lower left is printed on a paper with a more yellow luminescence than the surrounding areas.

The information revealed from these images can tell us more about how the Triumphal Arch was made, and can help to further inform the process of conserving the print.

The conservation of the British Museum Albrecht Dürer’s Triumphal Arch is generously sponsored by Howard and Roberta Ahmanson. To find out more, see the earlier blog post here.

You can see an interactive zoomable image of the print here.

Filed under: Conservation, Dürer’s Triumphal Arch, , , , , ,

Conservation of a clove boat

Verena Kotonski, Specialist Conservator (Organics), British Museum

In November 2014, my workbench temporarily turned into something close to a shipyard when a model boat made of cloves arrived in the Organic Artefacts Conservation Studio. Every object that goes on temporary or permanent display at the Museum receives a thorough condition check and, if necessary, conservation treatment before its installation in an exhibition. The clove boat was to be included in the exhibition Connecting continents: Indian Ocean trade and exchange, in which it was to be displayed for the very first time.

I have come across many weird and wonderful objects over the years, but never a boat made of cloves! I was particularly looking forward to unpacking this object from its storage box to see what it looked like. When I opened the box, an almost overpowering smell of cloves was released, which was somewhat of a surprise as this boat was probably made during the 18th–20th centuries in Indonesia and was accessioned into the collection in 1972.

1_Boat & crate

Model boat after unpacking from its storage box. Model Boat, AD 1700s–1900s, probably from Indonesia, L 58 cm, H 30 cm, D 23 cm As1972,Q.1944

Condition
A thorough examination of the object revealed that the structure of the boat was reasonably stable, but a significant number of elements (14 altogether) had become detached over time. It was difficult to establish the extent of missing elements at this stage. Furthermore, a considerable amount of dust had accumulated on the surface. In order to make this object fit for display, the surface would have to be cleaned, the detached elements reinstated on the object and missing elements reconstructed if and where appropriate.

Cleaning of the surface
Centimetre by centimetre I slowly worked over the object, removing the dust from the surface. This allowed me to appreciate the boat in detail; its decorative scheme and the intricate details of the cloves themselves. The boat is constructed of cloves that are either strung on one or two threads, or threaded on thin wooden pins. The hull is built from strings of cloves layered on top of each other and tied together. I also discovered, for example, that the arms of the figures on the boat and the paddles they are holding were made as one element, which was then adhered to the torso.

It was lovely to see the creative way in which the four unopened petals of the cloves that form a small central ball were used to either depict the head of a rower, the knob at the end of a paddle, or were used as decorative architectural elements.

Tools and materials I used to remove the dust were: a soft, fine tipped brush, vacuum suction and a special conservation-grade natural rubber to catch and trap the more ingrained particles.

Model boat during cleaning treatment (right-hand side – after cleaning)

Model boat during cleaning treatment (right-hand side – after cleaning)

Stabilisation of broken elements
Work to stabilise the boat and its occupants included mending a break in one of the corner posts of the cabin and securing several sets of arms and paddles to the torsos of the figures. For this, I used a conservation-grade adhesive, hydroxypropylcellulose, that has good ageing properties, which means that it will remain reversible should the need arise to undo the repair in future. In order to hold the elements in place until the adhesive had set, a range of different devices were employed to apply gentle pressure, such as light weight carbon clamps, hairclips, pins padded with silicone tubing and a bamboo stick mounted on what is actually a brush washer.

3_During clamping

Different clamping devices in action

Reinstating the detached figures
Finding the original location of the figures that had become detached from the boat proved less straightforward than I initially thought. I found 14 detached elements on the boat: 5 torsos, 1 standing figure, 2 sets of arms and paddles, one long paddle rudder (?), 1 pennant (long tapering flag) without pole and 3 round-shaped objects.

Detached elements including a long paddle (rudder?), a flag and a drum shaped element with a stick attached (left)

Detached elements including a long paddle (rudder?), a flag and a drum shaped element with a stick attached (left)

Due to the vacant places among the rowers and a set of holes in the bottom at the stern it was fairly obvious where two of the torsos (including the respective arms and paddles) were meant to go, as well as the figure standing upright. It was possible to attribute a set of arms and paddle to the respective torso by matching the shape of the cut-out on the cloves forming the shoulders with the shape of the stick that forms the neck.

Having reinstated the standing figure and two rowers, I was still left with three torsos and two drum shaped elements as well as the pennant. Although the Museum’s records, which include a rather vague historic drawing, hinted at the possibility that some figures could have been on top of the cabin including a second pennant, the exact location of figures and pennant remained difficult to establish.

Drawing of the boat found in the Museum’s records

Drawing of the boat found in the Museum’s records

Fortunately, research into similar models carried out by Charlotte Dixon, Collaborative Doctoral Award PhD Student at the University of Southampton and the British Museum, provided me with a chance to compare our boat with photos of a boat held in the Kew Gardens Economic Botany Collection, which Charlotte kindly shared with me. This strikingly similar boat shows three figures with round elements in front of them on top of the roof of a cabin. Further research by Charlotte also established that the round elements might represent drums. Close examination of the break edges on both drums under the microscope established from which torso one of the drums had broken off, and allowed me to reattach it accordingly.

Despite the very revealing and informative images of the boat at Kew, the numerous holes in the roof canopy offered little guidance on how the torsos might have been arranged on the roof. The ethics of reinstating the detached figures without knowing their original location was discussed with Charlotte and Sarah Longair, curator of this exhibition. We decided in favour of installing the figures on the roof. We felt that the figures (drummers) are a key part of the object and therefore vital for the interpretation of this artefact. Furthermore, it is possible to install the figures securely without using any adhesive which means they can easily be removed and repositioned if further evidence on their original position should emerge. Knowing that the figures on the roof were meant to depict drummers certainly helped to find a sensible arrangement of the figures on the roof.

Torsos of drummers after installation on the roof top. The original location of the drum shaped element (front) with stick attached is still unclear

Torsos of drummers after installation on the roof top. The original location of the drum shaped element (front) with stick attached is still unclear

Reconstruction of missing parts
There were still a long paddle (rudder?), pennant and a drum with a pole attached, for which I hadn’t found a location. Unlike the other detached parts these three would have required substantial reconstruction of missing elements in order to be able to reinstall them. As there were no hints where those elements would have been situated originally and what the now missing elements had looked like, we decided not to include them on the boat. Instead, they were packed safely to go into the object’s storage box.

One exception to this was the reconstruction of a missing retaining collar, which was vital for the object’s stability. These collars on top of each corner post of the enclosure prevent the roof canopy from lifting off the upright poles. One was reconstructed using tinted Japanese tissue paper rather than a clove in order to distinguish the later addition from the original object. This detail, which could have been easily overlooked, highlights how important it is for the conservator to understand how an object was constructed in order to inform the decisions about treatment that ensure the long-term stability and integrity of an object.

7_Retaining collar

Retaining collar made of Japanese tissue paper to replace the missing collar of this corner post

Call for action
After 34 hours of conservation work, which included the time for investigation and discussion with curatorial colleagues, the model boat was ready to sail and take its place on its tailor-made mount, created by Amanda Gregory, Senior Museum Assistant in the Department of Coins and Medals. My sincere thanks go to Charlotte and Sarah for their enthusiasm and constructive support in the course of this project as well as other colleagues who contributed to the success of this conservation project. Thank you also to Imogen Laing, Museum Assistant in the Department of Africa, Oceania and the Americas, for providing me with an image of the historic drawing of the boat.

Despite all our efforts, not all questions regarding the correct original position of some detached elements have been solved. Therefore, I would like to extend an invitation to the readers of this blog to get in touch should they have further information about the position of the rooftop figures, the drum (?) with pole attached, the second pennant and/or about the arms and paddle (rudder?) of the standing figure. Please contact us via conservation@britishmuseum.org with any information that might help.

Connecting continents: Indian Ocean trade and exchange is on display at the British Museum until 31 May 2015.

Filed under: British Museum, Conservation, , , , , ,

Conserving Dürer’s Triumphal Arch: a moving experience

Joanna Kosek, conservator, British Museum

Dürer's paper triumph: the arch of the Emperor Maximillian

The display of Albrecht Dürer’s (1471–1528) monumental Triumphal Arch in the Asahi Shimbun Display in Room 3 in autumn 2014 was a great success. The enormous print, produced at the height of Dürer’s career to glorify the reign of the Holy Roman Emperor Maximilian I (r. 1486–1519), appeared appropriately majestic in the softly lit room and attracted over 70,000 visitors in three months. Originally designed to be pasted on the walls of princely castles, the impression at the British Museum was never used as originally intended, and is one of only a handful to have survived. In the Museum the print, which measures four metres by three metres, had been lined onto a textile backing and had long been displayed in a massive frame by the Gallery Café. After the Room 3 show it was time to take the print down to inspect, conserve and store it in darkness to help preserve it.

Dismantling the exhibition started with detaching the glazing which consisted of three four-metre-high pieces of laminated glass that had been painstakingly installed back in September by expert glass handlers.

Now we watched the delicate operation of lifting the heavy glass in the reverse order of installation and, yet again, held our breath when giant suckers manoeuvred the heavy green-tinted glass panes, one by one, to expose the beautiful cream-coloured early 16th-century paper.

Detaching the glazing from the print.

Detaching the glazing from the print.

In the meantime, in preparation for taking the print down, we had constructed a huge half-metre-diameter tube in the Museum’s state-of-the-art Paper Conservation Studio. This ‘quicker-by-tube’ production needed to be sturdy but light. As nothing like this was commercially available, the team of conservation mounters made their own using transparent plastic sheeting filled in with foam padding and cardboard rings to prevent collapse, which could damage the print. There was a lot of laughter as two of the team plunged inside the roll to fix the padding! No effort was spared to make the roll perfect for the job.

The specially made tube being carried to Room 3 via the Great Court.

The specially made tube being carried to Room 3 via the Great Court.

The day of the great descent arrived on 17 November. Equipped with two scaffolding towers and supported by heavy object handlers and curators, and filmed by the Museum’s Broadcast team, we first attached the top edge of the vast print to a four-metre-long rod using heavy linen tape.

Attaching top edge of the print to a rod and taking the print down.

Attaching top edge of the print to a rod and taking the print down.

We could then slowly lower the rod plus print down through three successive platforms from person to person and from hand to hand. The print itself was also supported on a huge sheet of plastic with its sides and bottom held taught. Soon Dürer’s masterpiece was safely supported on the floor, and the moving of this flat paper giant did not seem such a difficult challenge now…

Inspecting and rolling the print up for transport.

Inspecting and rolling the print up for transport.

With so many helpful hands to roll it safely, in no time the print was taken onto its grand ascent to our Paper Conservation Studio in the World Conservation and Exhibitions Centre. As we had already rehearsed the route carrying the empty roll, we had no surprises, although that did not apply to crowds of bewildered visitors.

The print being taken through the Great Court to the World Conservation and Exhibitions Centre.

The print being taken through the Great Court to the World Conservation and Exhibitions Centre.

At last the arch was unrolled on the large tables in the Studio and while admiring it and planning what should come next we posed for picture as a memento.

The print laid out in the WCEC Paper Conservation Studio.

The print laid out in the WCEC Paper Conservation Studio.

The conservation of Dürer’s Triumphal Arch has been made possible by the generous support of Howard and Roberta Ahmanson.

You can see an interactive zoomable image of the print here.

Filed under: Conservation, Dürer’s Triumphal Arch, , , , , , , ,

Bringing a Ming painting back to life

Jin Xian Qiu, Senior Conservator of Chinese Paintings and Carol Weiss, Conservator of Chinese Paintings, British Museum

On entering the BP exhibition Ming: 50 years that changed China, one of the first objects visitors see is a large silk painting depicting an official in front of Beijing’s Forbidden City. This Ming dynasty painting by artist Zhu Bang was conserved especially for the exhibition, using traditional Chinese scroll mounting techniques that have been passed down from master to student since before this 500-year-old painting was even painted.

The British Museum is extraordinarily fortunate to have as its Senior Conservator of Chinese Paintings Mrs Jin Xian Qiu, who originally trained and worked in Shanghai Museum before coming to the British Museum 27 years ago. It is thanks to her expertise that many of the Museum’s Chinese paintings can be displayed today. For this particular project, along with the help of her assistants and colleagues in the Hirayama Studio (part of the British Museum’s Department of Conservation and Scientific Research, working on East Asian paintings) Mrs Qiu was joined by Mr Chu Hao, a Senior Paintings Conservator from Shanghai Museum, who assisted with some of the processes that make up this painstaking treatment.

Anonymous, Portrait of an offical in front of the Beijing imperial palace, hanging scroll, ink and colours on silk, c. 1480-1580 (British Museum 1881,1210,0.87.CH). Before conservation.

Anonymous, Portrait of an offical in front of the Beijing imperial palace, hanging scroll, ink and colours on silk, c. 1480-1580 (British Museum 1881,1210,0.87.CH). Before treatment.

Traditionally, East Asian scroll paintings are habitually conserved and cared for over the course of their lifetimes by a process of remounting. The paintings themselves are cleaned and repaired, whilst the surrounding silk borders and accompanying lining papers are replaced with new materials. It is because of this remounting that many silk paintings survive today as hanging scrolls. Because our painting was in poor condition, it was decided to completely remount it.

Before any work could start on the painting, its condition was documented using detailed photography and microscopy. At the same time, appropriate materials had to be prepared and sourced; from dyeing the new first lining paper to exactly the right shade and tone, to finding matching old silks to repair all the missing areas. Mrs Qiu donated a Ming dynasty silk, which matched very closely the colour and weave of the painting, from her own collection (which was passed down to her by her scroll mounting teacher in Shanghai).

Strengthening pigments with nikawa (a traditional East Asian consolidant)

Strengthening pigments with nikawa (a traditional East Asian consolidant)

After consolidating any vulnerable pigments, the treatment could begin. The old unsuitable mount was removed from the painting, and in the process of doing so, wider hidden painted edges and more of a seal were revealed. The painting was then ‘washed’ four times in a wet treatment that removes acidity and discolouration from the silk. This process involves carefully sprinkling water onto the surface of the painting before gently removing the excess.

After cleaning, in order to stabilise the silk weave during the upcoming treatments, a temporary facing was applied to the painting’s surface, now nicely flattened by the wet treatment. This facing is made of tong oil paper (a specially treated water-resistant paper) with further layers of xuan paper (a short-fibred paper used in all Chinese scroll mounting and much East Asian calligraphy and painting) applied on top for extra stability.

Mrs Qiu with her two assistants, Valentina Marabini and Carol Weiss, removing the painting’s old backing papers

Mrs Qiu with her two assistants, Valentina Marabini and Carol Weiss, removing the painting’s old backing papers

With the surface protected, the painting could be turned over and stuck to the table face-down to reveal many layers of backing papers. These were removed with tweezers, sometimes in long strips, sometimes fibre by fibre, along with old unsuitable silk repairs. Only now was the real extent of damage to the painting revealed, and while still damp, misaligned silk pieces were carefully realigned to their correct positions.

Mrs Qiu repairing the missing silk areas

Mrs Qiu repairing the missing silk areas

Once dry, the process of silk repair could begin, being careful not to waste any of the precious ancient silk resources. Shaped patches of repair silk were adhered to the back of the missing areas and once dry any overlapping edges were carefully pared away. Because the painting was in such bad condition, this process alone took three conservators working for around six weeks.

Mrs Qiu with her assistants and Mr Chu Hao from Shanghai Museum, after the painting has been lined and its facings removed.

Mrs Qiu with her assistants and Mr Chu Hao from Shanghai Museum, after the painting has been lined and its facings removed.

It was at this stage that Mr Chu Hao from Shanghai Museum joined the team to help apply the new lining papers. The first lining was dyed Chinese xuan paper, and the second, long-fibred Japanese usumino paper. Mrs Qiu developed this technique, which she thinks provides extra strength, after coming to the British Museum’s Hirayama Studio, where our Chinese and Japanese expert scroll mounters work together – a wonderfully unique situation, and one of its kind here in Europe. After this double-layer of lining was applied to the painting using wheat starch paste, it could be turned over and the temporary facings removed. Then it was applied to a drying board to allow the process of toning the repairs to begin.

Mrs Qiu and Mr Chu Hao retouching the painting on the drying board.

Mrs Qiu and Mr Chu Hao retouching the painting on the drying board.

With the conservation aspect of the treatment finished, the mounting work could begin. Mount silks were lined and dyed to best enhance the painting, before being cut into carefully proportioned rectangles that were adhered to the painting’s edges to make an aesthetic border. Slender paper reinforcement strips were applied to the back of the lined painting wherever there was previously a crack or crease, and then the whole mounted painting was given a final backing of two layers of xuan paper with cover silk at the top (to protect the scroll once rolled). This was attached to the drying board for many months, before it was removed and the back burnished, producing a smooth finish ideal for a scroll that will be rolled up. Finally, wooden fittings including the top stave, bottom roller and roller knobs were attached, and the hanging braid and tying ribbon tied on to produce a finished hanging scroll.

Anonymous, Portrait of an offical in front of the Beijing imperial palace, hanging scroll, ink and colours on silk, c. 1480-1580 (British Museum 1881,1210,0.87.CH). After conservation.

Anonymous, Portrait of an offical in front of the Beijing imperial palace, hanging scroll, ink and colours on silk, c. 1480-1580 (British Museum 1881,1210,0.87.CH). After conservation.

From undertaking the first analysis to tying the final ribbon, the entire process took over a year, with other paintings worked on during the long periods of drying. The painting is now stable and can be rolled and unrolled for display without risk of damage; the silk has been cleaned and strengthened by the washing and repair processes and the entire painting has been flattened by its new lining. Details in the painting, previously hidden by stains or creases, are visible once more. A hundred or more years should pass before this painting will need to be remounted again, its journey of conservation and potential to be preserved never-ending while there are still expert scroll mounters to care for these works in the traditional Chinese style.

The BP exhibition Ming: 50 years that changed China is at the British Museum until 5 January 2015.
Supported by BP

The exhibition catalogue, The BP exhibition: Ming: 50 years that changed China, edited by Craig Clunas and Jessica Harrison-Hall, is available in paperback and hardback from the British Museum shop online

Filed under: Conservation, Ming: 50 years that changed China, , , , , , , , , , ,

One night at the Museum: moving Dürer’s paper triumph

Joanna Kosek, conservator, British Museum

Preparing for the move.

Preparing for the move.

Once the final visitor had departed from the Museum on Monday 14 July 2014 at 5.30pm a sizable team of specialists consisting of heavy-object handlers; exhibition designers, curators, conservators and photographers assembled in Room 12a in front of the world-famous woodcut of the Triumphal Arch by Albrecht Dürer (1471–1528).

Albrecht Dürer, The Triumphal Arch, woodcut print on paper. (E,5.1)

Albrecht Dürer, The Triumphal Arch, woodcut print on paper. (E,5.1)

One of the largest prints ever produced, this fantastic arch on paper was commissioned by the Holy Roman Emperor Maximilian I (r. 1486–1519) to rival the arches of the ancient Roman Emperors as his own propaganda piece. Unlike the stone forerunners of antiquity, his print came in multiple copies out of Dürer’s workshop for distribution throughout the Holy Roman Empire. The giant print measures nearly 4 x 3 metres and was originally printed from 195 separate woodblocks. The copy in the British Museum’s collection arrived in 1834, and was eventually housed in its current enormous metal frame in the 1970s.

Now it was needed to be the star in the new Asahi Shimbun Display Dürer’s Paper Triumph: the arch of the Emperor Maximilian in Room 3. Our task that night was to take it out of the frame and remove the glass in preparation for its move across the Museum. There were many unknowns ahead of us – we didn’t know precisely how the frame was constructed or attached to the wall. All we knew for certain was that the whole thing was extremely solidly made and incredibly heavy.

The glass taped up and the print in the process of being detached from the wall.

The glass taped up and the print in the process of being detached from the wall.

Fig 2 ii_544x725

This operation was preceded by months of planning and generated the fattest risk assessment folder ever seen. We began by taping the glass using the toughest tapes in the building, after which we had to lift the frame from the wall. This turned out to be fixed to large steel brackets bolted to the gallery wall and must have weighed nearly half a tonne. This first operation took at least four hours and we all held our breath until the frame, ingeniously, was raised and detached by a large lifting frame, normally used by the National Gallery to take their largest altarpieces off display and kindly lent to us for the job.

Removing steel frame components

Removing steel frame components

We could then dismantle the frame into four separate components. Once this was done we could assess the construction of the mount and backing. It was at this stage that we also realised that we were dealing with 10mm thick plate glass weighing about 150kg in total.

It took some four hours of carefully considered steps before, at around 3am, the glass was finally separated from the print with full precision and total control. The print, escaped from the green-tinted glass, turned out to be a beautiful impression on choice early 16th-century paper.

The plate glass detached from the print.

Plate glass detached from the print.

The plate glass swivelled to lay flat on the floor.

Plate glass swivelled to lay flat on the floor.

At last Dürer’s masterpiece could be fixed to a temporary aluminium support frame and screwed onto the wall without the threat of the glass breaking. Meanwhile, glass experts attached massive spider-like suckers to the centre of the glass, swivelled it flat on the floor, and cut it into metre-square pieces for safe disposal. It was now around 6am.

The print protected and ready for hoarding.

The print protected and ready for hoarding.

Hoarding being built around the Triumphal Arch.

Hoarding being built around the Triumphal Arch.

The moment the glass was wheeled out and we were all ready for bed, a team of joiners arrived to put up a protective hoarding around the print. They had exactly three hours before the Museum opened and worked like the flying squad, assembling 20 large panels into a neat white enclosure within the Minoan Gallery. I was handed the key to the great treasure chest just as the first visitor arrived at 10am on Tuesday morning.

The Asahi Shimbun Displays Dürer’s paper triumph: the arch of the Emperor Maximilian is in Room 3, from 11 September to 16 November 2014
Supported by The Asahi Shimbun

Filed under: Conservation, , ,

Conserving the pottery, terracotta and tablets from Ur

Duygu Camurcuoglu, conservator, Ur Project, British Museum

My job is to assess the condition of the objects from Ur being studied as part of the Ur digitisation project, conserve them if necessary, and guide the project team on handling and safe storage of the objects before/during photography and further digitisation work. I joined the project in August 2013 to lead the conservation and my first responsibility was to assess and conserve the terracotta objects and the clay tablets with ancient cuneiform inscriptions on study loan from Iraq.

Assessing the condition of the Humbaba terracotta mask

Assessing the condition of the Humbaba terracotta mask

Fired clay mask of Humbaba. Old Babylonian, 2000–1700 BC; From Ur, southern Iraq.  (ME 127443)

Fired clay mask of Humbaba. Old Babylonian, 2000–1700 BC; From Ur, southern Iraq. (ME 127443)

There are over a thousand terracotta objects from Ur in the British Museum’s collection, primarily reliefs, figurines and models. Although some are skilfully modelled, the majority are rather crude and mass-produced in moulds. My initial task was to assess each one, selecting those that needed treatment and completing the work before they could be handled and photographed. In the image above, you can see me assessing the condition of one of the important objects from Ur, the fired clay mask of Humbaba, a fearsome monster slain by Gilgamesh in Mesopotamian literature. During the process, colleagues from ceramics and glass conservation joined me to complete the assessment work on the objects, while I undertook the actual conservation treatments.

Following the terracotta objects, I assessed the condition of the pottery from Ur. This large collection comprises over a thousand ceramic vessels in various sizes, shapes, colours and fabrics. This was a huge challenge! Every day, my colleague Gareth Brereton and I went to one of British Museum’s storage areas where the pottery from Ur is housed. We set up a small working area in this room for object assessments, photography and registration. There were a large number of cupboards to go through, so Gareth and I worked almost every morning together, assessing the condition of each pot so that Gareth could handle, photograph and register them. We had plenty of exercise going up and down the ladder each morning as some of the objects were stored very high up in the shelves.

Most terracotta objects and ceramic vessels from Ur are in good condition. They sometimes require conservation work, since they have unstable fragments, flakes or cracks on their surfaces. This is very normal due to the age of the objects, most are which are about 4,000 years old. It is crucial that the necessary treatments are undertaken. When unstable objects are not treated using proper conservation techniques and materials, further problems may occur during storage and handling, such as loss of surfaces and decoration, cracks, breakage of fragments that can make it difficult to study and learn more from the objects.

Stabilising the surface of a large ceramic vessel from Ur

Stabilising the surface of a large ceramic vessel from Ur

I identify any cracks and/or unstable flakes on the surface of the vessels before stabilising them using conservation grade materials. I often use a fine brush or a micropipette for this work. Once the treatment is completed, I enter all my treatment records onto the British Museum’s curatorial database, Merlin, so that the information is accessible across the Museum and the world via the collection online.

Assessing a cuneiform tablet from Ur

Assessing a cuneiform tablet from Ur

I have also been assessing and undertaking conservation on the cuneiform tablets from Ur. It is particularly important to prevent the loss of surfaces from tablets, because that would mean loss of the text.

Apart from undertaking remedial ‘hands on’ work with objects, I am also responsible from supporting the Ur team when they have any questions about handling the objects safely, as some are very fragile. I also monitor the environmental conditions in the Ur project lab and storage cupboards, using digital sensors which we place in different areas. This is important because fluctuating temperature and relative humidity can severely damage archaeological objects. For example, soluble salts in the ceramic and clay fabrics can react very quickly with the fluctuating conditions, resulting in delamination and loss of object surfaces, which can contain elaborate decorations, pigments and reliefs.

When I have completed the conservation work on the pottery and the cuneiform tablets, I will move on to the conservation of other types of objects and materials from Ur, in order to prepare them for digitisation and further study. I am looking forward to the challenge!

Read more about the Ur digitisation project in Birger Helgestad’s post in July.

The Ur Project is supported by the Leon Levy Foundation.

Filed under: Conservation, Ur Project, , , , , ,

The Beau Street Hoard: Not quite the end… conservation, outreach and further investigations

replica of coin block before conservation
Hazel Gardiner, Metals Conservator, British Museum

The soil block after excavation of the hoard and prior to dismantling and return to the archaeologists who carried out the excavation.

The soil block after excavation of the hoard and prior to dismantling and return to the archaeologists who carried out the excavation.

For those who have been following the progress of the conservation of the Beau Street Hoard on the blog, I am delighted to announce that all the coins – around 17,500 of them – have now been cleaned to required identification standards, that is, to the point where the legend and significant features are readable. Conservator Julia Tubman carried out the bulk of this work on the c.17,500 coins contained within the hoard. Additional work has been carried out on a small number of these coins and conservation has also been carried out on c.400 coins that were initial finds from the outer edges of the hoard, before the hoard proper was unearthed. This last group of coins were in particularly poor condition and most required substantial chemical and manual cleaning. These coins were held in numbered paper envelopes, some of which corresponded to small find numbers allocated when the hoard was excavated.

Envelopes containing initial coin finds associated with the Beau Street Hoard

Envelopes containing initial coin finds associated with the Beau Street Hoard

The soil block that held the hoard has now been dismantled and returned to the archaeologists who carried out the initial excavation for final sifting and checking for palaeoenvironmental remains: that is, material that might provide further contextual information about the coin hoard.

A washed but otherwise untreated coin from surface scatter coins showing the thick cuprite (copper oxide) layer obscuring the surface.

A washed but otherwise untreated coin from surface scatter coins showing the thick cuprite (copper oxide) layer obscuring the surface.

At the time of Julia’s last post, she reported that one of the coin clusters (bag 4), had been scanned. As with the other coins in the hoard, the clustered corroded coins retained the positions that they would have held in the bag in which they had been deposited. In this instance the bag shape was particularly well preserved. The initial scan was carried out at the British Museum by Martin Cooper of the Conservation Technologies Unit, National Museums Liverpool (NML). The scan data was used to create a 3D computer model, which was then 3D printed to make a replica of the coin bag using Selective Laser Sintering (SLS), a process that uses a laser to fuse particles of plastic or other material into the required three-dimensional form. A plaster cast was then made from the print and this was painted to resemble the original coin cluster, by conservators at NML.

replica of excavated coin block

The replica of bag 4

The replica has proved very popular among visitors to the Roman Baths and was shown at a Beau Street Hoard community consultation event run by staff at the Roman Baths earlier in 2013. Members of Bath Ethnic Minority Senior Citizens Association (BEMSCA) were among those who handled the replica. As a three-dimensional record of the original form of the coin bag, which of course no longer exists now that the coins have been conserved, the replica is an excellent supplement to the information gathered about the hoard, an invaluable means of allowing people to gain some sense of the physicality of (at least part) of the hoard.

Further exciting news is the forthcoming analysis of what appear to be animal skin remains from the bags used to store the coins. In one of Julia’s earlier posts she noted that traces of what appeared to be skin product, preserved by metal corrosion products, were found on the outside of each cluster of coins, suggesting that leather bags may have been used to house the coins. Professor Matthew Collins and colleagues at BioArCh (University of York), are hoping to extract collagen from the samples provided and to identify the species of animal skin used. Identification of the animal species will be made by peptide mass fingerprinting, an analytical technique for protein identification. We look forward to hearing the results of their investigations.

Possible skin product preserved by corrosion products from the coin beneath.

Possible skin product preserved by corrosion products from the coin beneath.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

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Filed under: Beau Street Hoard, Conservation, , , , , ,

The Beau Street Hoard: counting ancient money

Beau Street HoardEleanor Ghey and Henry Flynn, British Museum

If you listen carefully outside the Department of Coins and Medals at the moment you may hear the chink of money being counted. It’s not a surprise donation or a lottery win, but Roman coins from the Beau Street Hoard being sorted into imperial reign, bag by bag, to obtain an idea of the date and contents of the hoard.

The hoard in May 2012 in the conservation lab, excavation underway.

The hoard in May 2012 in the conservation lab, excavation underway.

We collected the coins from conservator Julia Tubman in stages, as each bag was removed from the soil block the hoard was found in. Some are surprisingly heavy, about as much as I can lift comfortably. The silver coins have a pleasing weight in the hand and do not look over 1,700 years old.

An X-radiograph of the soil block before conservation taken at the Imaging Centre in the University of Southampton’s Department of Engineering Sciences. © University of Southampton

An X-radiograph of the soil block before conservation taken at the Imaging Centre in the University of Southampton’s Department of Engineering Sciences. © University of Southampton

The next stage of our work is to provide information on the hoard so it can be given a provisional valuation as part of the Treasure process. The hoard has already been declared Treasure at inquest under the Treasure Act 1996. Now the coins are almost all separate and reasonably clean, it will be possible for an independent expert to do this. As museum curators, we do not have expertise in questions of commercial value but we provide a listing of the contents. The provisional value is then considered by the Treasure Valuation Committee, which recommends a final value. The purchasing museum (in this case the Roman Baths Museum) is then able to raise funds for this amount, from which a reward is paid to interested parties (usually the finder and landowner) as applicable.

The results so far…

We have been able to sort and count seven of the eight Roman money bags contained within the hoard – one is still undergoing conservation. The total so far is 14,646 coins, but as the final bag is large we expect this to go up to over 16,000 coins.

A table showing the different types and amounts of coins in the hoard

A table showing the different types and amounts of coins in the hoard

In my previous post I described the three different types of coins in the hoard (denarii and early (silvery) and later (debased) radiates). With these three types of coins one might expect a wide date range between the bags. This has not been the case. We have the very latest denarii and late silver radiates, so that the bags could have been deposited within 20 to 30 years of each other (or sorted and re-deposited together). At the moment, the latest coins in the hoard date to the mid AD 270s quite precisely.

Parts of the hoard and some of the tools used by conservator Julia Tubman to excavate it on display

Parts of the hoard and some of the tools used by conservator Julia Tubman to excavate it on display

A conservation-themed display of the Beau Street Hoard is now on show in Case seven of the Citi Money Gallery. This case focuses on Treasure and hoarding and features a changing display intended to highlight new or exciting Treasure finds. The Beau Street display focuses on the excavation of the soil block and subsequent cleaning of the coins by Julia Tubman.

The content of the hoard is represented by three piles of coins – one pile of each denomination found in the moneybags – and the seven-week process of excavation and cleaning is illustrated using time-lapse video footage of the removal of the coins from the soil block.

An X-ray image, which provided the first visual evidence of the grouping of the coins and acted as a guide for the excavation, is also featured in the video. Some of the tools used by Julia during this process are displayed alongside the coins which have been cleaned for identification.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

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Filed under: Beau Street Hoard, Conservation, Money Gallery, ,

The Beau Street Hoard: the end of the excavation

Beau Street Hoard excavationJulia Tubman, conservator, British Museum

My last blog post recounted the excavation of bags 5 and 6 of the Beau Street hoard, which were the two smallest bags on the edge of the large hoard. In the months since, the deconstruction of the hoard has advanced considerably: as the excavation progressed I naturally became faster and more confident in removing the coins, and am pleased to announce the end of this stage of the project. The hoard was well organised, with the coins carefully sorted into bags according to denomination and level of debasement; specialists here at the British Museum now have a fascinating mystery to interpret.

The hoard towards the end of the excavation

The hoard towards the end of the excavation

In total eight bags were found in the hoard, which is two more than originally identified in the x-ray. Squeezed between the larger ‘bag 2’ and the centre of the hoard were two tiny bags, the coins of which are very similar to those contained within bag 2 – small radiate coins minted by Gallienus, Claudius Gothicus and Tetricus I.

Luckily, at the end of the excavation I was able to lift the large, central moneybag (known as bag ‘4’), whole, as I had removed all of the bags of coins surrounding it. The excellent preservation of this moneybag, which weighs nearly 11 kilograms, presents us with a very exciting opportunity. Already a laser scan of the bag has been undertaken to produce a rotating three-dimensional image, and a second scan will be taken before the end of the year which will be used to produce a facsimile to go on display in Bath. These scans provide us with a lasting document of the moneybag, which will now be de-constructed and the coins cleaned.

Moneybag 4

Moneybag 4

The block was x-rayed before the excavation of the moneybags, and so the base holding the coins had to be x-rayed after the removal of the last bag, to check that there were no ‘surprise’ bags beneath those already excavated. The x-ray showed only a few coins on the periphery of the base, and so we can move towards giving a final count for the number of coins in the hoard as a whole: at the moment it looks to be around half of the original estimate of 30,000.

Now the excavation is complete, I will be fully focused on getting all of the coins cleaned so that they can be identified by numismatists, who will begin to compile an ‘Emperor count’.

We knew at the beginning of the project that this would be a short excavation, and the perfect opportunity to experiment with time-lapse photography. Before I began the excavation, a camera was positioned on a workbench above the hoard, and programmed to take a photograph of the stationary block every 10 minutes. This short video neatly captures the deconstruction of the hoard, and makes for a fantastic record of the excavation.

On Friday 30 November, Stephen Clews from the Roman Baths, British Museum curators Richard Abdy and Eleanor Ghey, and I will be discussing the story of the Beau Street Hoard so far in a lecture at the British Museum.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

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Filed under: Beau Street Hoard, Conservation, Research, , , ,

A closer look at what the Chiseldon cauldrons are made of

High magnification image of one of the cauldrons

Quanyu Wang, scientist, British Museum

I am a scientist specialising in metalworking technology, particularly in relation to non-precious metals such as iron and copper-alloys. The scientific examination and analysis of the Chiseldon Iron-Age cauldrons is a key aspect of the investigative process as a whole and is crucial in supporting our understanding of them.

For the Chiseldon cauldrons I have been examining the microstructure of the metal under very high magnification in order to see its composition, deduce how it was worked and explore manufacturing techniques. Some of the questions I will be trying to answer include: ‘How were the cauldrons made?’, ‘Were different components from an individual vessel made in the same workshop?’, ‘Were the same parts, such as the iron handles for different vessels, made from the same metal stocks’ and, perhaps the most important question of all; ‘Were the cauldrons made especially for burial or collected together for a particular occasion?’

Taking a sample from one of the cauldrons

Taking a sample from one of the cauldrons

Finding appropriate samples to test can be extremely difficult as the metal, particularly the iron, is extremely corroded and very fragile. The sampling process is made additionally complicated by attempting to sample a potential area that is as discrete as possible to make sure that we do not endanger the structural integrity of the artefact but will yield the best results. This is not a decision that is taken lightly and sample positions are chosen in consultation with curators and conservators. In order to reveal the structure of the metal the samples are mounted in resin, their cross-section polished, and then examined using metallographic microscopy up to x1000 magnification and a scanning electron microscope equipped with energy dispersive X-ray spectrometry (SEM-EDX) that allows us to examine them up to 300,000 times its actual size.

We have been able to deduce that the iron handles from both the cauldrons studied so far were probably formed by repeatedly hammering an iron bar while it was rotated. Additionally, iron used for the same parts of different cauldrons showed differences in microstructure and slag (impurity) inclusions, and was therefore from different stocks of metal, suggesting that these cauldrons were probably collected together rather than being made at the same time specifically for burial.

A high magnification scanning electron microscope (SEM) image of a copper alloy sample from one of the cauldrons. Darker horizontal lines were caused by many cycles of working and heating

A high magnification scanning electron microscope (SEM) image of a copper alloy sample from one of the cauldrons. Darker horizontal lines were caused by many cycles of working and heating

The copper-alloy is likely to have been subjected to many cycles of working and annealing (heating) to reduce the sheet metal to its final thickness (and shape). Significantly, there are differences in the content of sulphide within the copper alloy from one of the cauldrons, which suggest that the metal of the bowl and that of the band were probably refined to different levels or were from different sources.

Some of the results we have achieved so far are intriguing and much more revealing than expected given the condition of the material. Further analysis of the remaining cauldrons will not only provide further details of how the metal was processed and how the cauldrons were made but will help us build up a more complete picture of the deposit as a whole.

The Chiseldon cauldrons research project is supported by the Leverhulme Trust

Find out more about this research project

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Filed under: Archaeology, Chiseldon cauldrons, Conservation, Research

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