British Museum blog

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

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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.

If you would like to leave a comment click on the title

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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.

If you would like to leave a comment click on the title

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.

If you would like to leave a comment click on the title

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

The Beau Street Hoard: the view from Bath

A gallery display at the Roman Baths Museum, Bath


Stephen Clews, Manager, Roman Baths and Pump Room

The Beau Street hoard was found in the old spa quarter of Bath, where a nineteenth century hospital building is being converted into a five star hotel next to the city’s modern spa and close to the heart of the old Roman town of Aquae Sulis.

The site is very close to two of the city’s three hot springs. Excavations in the nineteenth century in advance of the hospital revealed evidence of a Roman bath house adjacent to one of these springs, so it was expected that some interesting Roman archaeology might be revealed by excavations here. But a large hoard of coins was completely unexpected.

The excavation of the Beau Street Hoard. © Cotswold Archaeology

The excavation of the Beau Street Hoard. © Cotswold Archaeology

There are no other large hoards of Roman coins known from Bath. Nor is there anything about the known archaeology of the site or indeed any other evidence from Bath that would lead us to expect the discovery of what is now the largest hoard of Roman coins yet discovered from an urban context in Britain.

The Roman Baths intends to acquire this hoard through the Treasure process and put it on prominent display in a gallery devoted to the story of Aquae Sulis. Here it will be seen by the around a million visitors who come to see what is already one of Britain’s principal Roman sites every year.

At the moment, we’re working to raise money for the acquisition and would like it to be a process in which we can celebrate the discovery of the hoard and use it as a spring board for a wide range of learning and cultural activities inspired by it. Together with the British Museum and several other organisations we are working up ideas for a programme that will run alongside the conservation, acquisition and display of the hoard.

The Roman Baths Museum. © Bath & North East Somerset Council

The Roman Baths Museum. © Bath & North East Somerset Council

Although there will be opportunities to take part in these events and see many of the coins in advance our target is to put the hoard on permanent display towards the end of 2014.

But, for now, with each coin that emerges, we’re trying to work out why the hoard was buried in the first place. So far the latest coin discovered dates to 274 AD, and although this was a time of great unrest in the Roman Empire there has been no indication of this in the archaeological record from Bath. Troubled times are not always the reason for the deposition of hoards, but they are an obvious reason to consider.

Burial of the coins as an offering to the gods seems unlikely in this case – as just a few yards away more than 12,000 coins have been recovered from excavations of a Sacred Spring where they were thrown in as offerings directly to the Goddess Sulis Minerva. In Bath that was the obvious way to make an offering.

Objects found at a sacred spring in Bath. © Bath & North East Somerset Council

Objects found at a sacred spring in Bath. © Bath & North East Somerset Council

The hoard was buried in a stone-lined box set into the floor of a Roman building. It was presumably covered over, perhaps by wooden boards or a piece of furniture to hide its presence. Whatever the means, it certainly seems to have achieved its object. A personal loss of a family fortune? Perhaps an elderly batchelor living alone with his inheritance hidden safely away? In which case the hoard may have been buried some years later than its youngest coin suggests.

We could imagine many other scenarios to account for the hoard. Whatever the reason, the hoard that now survives has brought a new dimension and a new story to our thinking about the development of Roman Bath that ranks with many of the other great discoveries made here.

The 300-year-dig at Bath that began with the discovery of the gilt bronze cult statue of the goddess Sulis Minerva in 1727 is still giving up secrets!

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

If you would like to leave a comment click on the title

Filed under: Beau Street Hoard, Conservation

The Beau Street Hoard: excavation progress

Julia Tubman, conservator, British Museum

As mentioned in previous blog posts, the Beau Street Hoard is not just one huge jumbled mass of coins, but actually at least six separate bags. My excavation plan is to remove these coins bag by bag, to preserve the groupings (which are potentially very significant), and give us a clearer view of the size and shape of each bag.

I had been concerned that the coins might have concreted together to such an extent that identifying separate bags would be very difficult during the excavation, but (fingers crossed!) thus far the removal of individual bags has progressed remarkably smoothly. I have managed to retrieve two whole bags of coins. I have numbered these bags five and six, and they are the two smallest bags at the northern end of the block in the x-ray (five being the smallest).

The block, after the removal of bags 5 and 6

We were excited to see that bag six almost exclusively contained denarii (the smaller coins with a high silver content discussed in Eleanor’s blog post last week), suggesting that the coins might have been bagged by denomination. Of the approximately 3,000 coins I excavated of this bag, I have cleaned around 1,000, and thus far the latest coins we have date to the third century AD.

There are actually a very small number of coins older than the third century contained within the bag: one coin was minted during Otho’s very short reign (AD 69), and an even older one, worn almost flat, minted at the end of the Roman Republic by Mark Antony (just prior to the battle of Actium in 31 BC).

This means that some of the coins were centuries old at the time of the final deposition of the hoard. As I’m cleaning the coins bag by bag in the order excavated, I haven’t yet got round to cleaning the coins kept in bag five, but thus far these all appear to be radiates.

A very worn coin minted by Mark Antony, circa 31 BC

As you can see in the photographs, it is quite easy to tell where one bag ends and another begins. The orientation of the coins themselves and the very bright blue corrosion helps a lot, but there are also other markers. The bags that held the coins would have been organic in nature (made from either an animal or plant product).My guess would be leather as they would have to be strong enough to hold large numbers of coins. Unfortunately, even organic material which has been treated and processed to form objects doesn’t always survive easily in Britain, which is why most of our surviving artefacts are made from stone, ceramic or metal. With this in mind, I knew that any piece of bag that might have survived would be in very poor condition, and I was prepared to look for scant pieces of evidence preserved in the corrosion generated by the coins.

Denarius bearing the emperor Septimius Severus, AD 193-211

Happily though, I think that I have found fragments of leather (see the light brown material loosely attached to the coins), exactly where I know the bags would have been. The leather is obviously very degraded, and as the fibre network has broken up, the leather has shrunken and split resulting in the flaky incoherent material we see today. I have taken some samples of this material, and hopefully my identification of this will be confirmed by a specialist soon.

The next stage of the excavation- the removal of bag 2

After three weeks I now have a much better understanding of the size and shape of the hoard. There were no more coins beneath bags five and six, but the x-rays taken through the side suggest this is not the case throughout the rest of the block – we suspect there might be more bags of coins beneath the six already identified.

The area excavated thus far shows that the floor of the cist is obviously not even, but seems to have been dug in a rough pit-like way. As yet I have found no evidence of any kind of wooden box that might have held all of the bags, and as I have found pieces of tile pressed up against the coins, I actually doubt that there ever was.

Given the way in which the bags have been piled (I do not want to destabilise the central bags by removing their supports), and to get an idea of what the bags of coins in the middle of the block look like, I will now begin excavating ‘bag two’ at the southern end of the block. I’m sure there will be more exciting developments to report.

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

If you would like to leave a comment click on the title

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

The Beau Street Hoard: what’s in the box?

Eleanor Ghey, project curator, British Museum

Hoards of Roman coins from later in the third century AD are the most common sort of coin hoards we see at the British Museum but the Beau Street Hoard is very unusual. When I saw the X-ray of the hoard I was very excited to see what looked like clearly separate bags of coins deposited in a group – normally coins are found in a pot or in a hole in the ground together in one lump. Here we have at least six (and probably more) groups of coins – several hoards in one! It was even more exciting to learn that it was going to be possible for my colleague Julia Tubman to isolate the groups.

It raises all sorts of questions. Do the bags contain the same sorts of coins or different ones? Do they each contain the same amount in Roman money or in weight of metal? Are they all coins that were circulating at the same date or are they deposits of coins from different time-periods gathered together at a later date for re-burial?

An X-radiograph of the soil block before conservation. © 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

It is already possible to start to speculate about the contents of the hoard from the few coins that have been removed from the block (although it may still hold surprises). The coins are mostly of the denomination known as a ‘radiate’ (from the spiky crown the emperor wears on the obverse (front) of the coin).

A silver radiate of Gordian III from the hoard

A silver radiate of Gordian III from the hoard

This type of coin first appears in the early third century AD and at the time was of a value double that of the denarius (the main silver coin in the earlier years of the Roman Empire). Initially, like the denarius this was a silver coin. Gradually over time the silver content of the radiate was reduced, until (by the 270s AD) they were almost entirely base metal (copper alloy) and became smaller in size.

The first coins Julia removed from the block were large and silvery in appearance (once cleaned) and came mostly from the first half of the third century AD. The earliest coin was a denarius of the emperor Septimius Severus (ruled AD 193-211) and the latest were coins of the emperor Gallienus and his wife, Salonina, dated to the AD 260s. This would be fairly typical for the contents of a hoard buried in the AD 260s.

A silver denarius of Septimius Severus (AD 193-211) from the British Museum collection

A silver denarius of Septimius Severus (AD 193-211) from the British Museum collection

However, when the hoard was first discovered, a sample of coins taken from another area of the block was quite different in nature. These were the smaller, more coppery radiates of the AD 270s (the most common type of coins we find in hoards from the 270s to 290s). This suggests that we may be dealing with bags containing different groups of coins, possibly gathered together at different times or sorted before burial.

Was this a secure store for bags of money that was added to gradually by one or more people over a fairly long period of time? It seems like an official store of money, organised into bags and purposely concealed in a place designed for that purpose. It was certainly a large amount of money (although we don’t have data for the later third century, pay scales for legionary soldiers in the AD 230s suggest they would have received about two and a half of these coins as a day’s wage) and it could have been looked after by an individual with authority.

It is rare to find hoards in Roman town centres. Perhaps it belonged to a local business in what was a busy town centre (deposited in a safe place in the way we leave money at the bank today). Why was it left for the archaeologists to find and not recovered by its owner?

Was there any connection with the nearby temple and sacred spring? We know that temples had treasuries; they may have periodically emptied out some of the coins thrown into the spring.

We are hoping that results from the archaeological excavation of the findspot will shed further light on this puzzle.

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

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

The Beau Street Hoard: excavating Roman treasure, one coin at a time


Julia Tubman, conservator, British Museum

In November 2007, during a routine archaeological excavation in advance of building work in Beau Street, Bath (a stone’s throw from the famous Roman Baths themselves), archaeologists came upon what was clearly a very large number of coins contained within a cist (a stone-lined box). Upon further excavation, they quickly came to realise they were looking at one of the largest coin hoards found in the UK, representing quite a tumultuous time in Roman Britain – about AD 270.

Some of the coins from the hoard during the initial excavation © Cotswold Archaeology

Some of the coins from the hoard during the initial excavation © Cotswold Archaeology

When groups of coins that appear to be over 300 years old are found, they must be reported to the local coroner (according to the Treasure Act 1996). The coins enter what we call the ‘Treasure Process’ where, if necessary for identification, they will be cleaned in preparation for their formal declaration as Treasure and the property of the Crown, or eventual valuation. Usually this occurs at the British Museum, or in the case of Welsh Treasure cases, the National Museum of Wales.

The hoard was lifted in a single soil block © Cotswold Archaeology

The hoard was lifted in a single soil block © Cotswold Archaeology

In order to preserve its shape and context, the archaeologists cut around the hoard and lifted it in a soil block. As a metals conservator at the British Museum, my job is to excavate the coins from the soil and clean them up. The initial excavation should take about six weeks and during that time I will be regularly adding to this blog with updates of my work as it progresses. Colleagues from curatorial departments and our science team who are involved with the project will also contribute as the hoard gradually reveals its story.

The hoard in its soil block when it arrived in the conservation lab at the British Museum

The hoard in its soil block when it arrived in the conservation lab at the British Museum

The coins are currently held together by soil and metallic corrosion. They are blue and green in colour indicating the corrosion of a copper metal, which would have been used as a base alloy for the coins. Interestingly, within this copper corrosion is actually a layer of silver that was plated over the copper during the manufacture of the coins.

The coins have also maintained the shape of the cist they were contained within, as the soil and corrosion has concreted together. Looking more closely, we can even see that there are groups of coins within the hoard; which is because this large hoard appears to be composed of six individual smaller hoards.

We had an idea that this could be the case because in December last year Dr. Mavrogordato, from the Imaging Centre in the University of Southampton’s Department of Engineering Sciences, kindly took x-rays of the block. The resulting images show what look to be ‘bags’ of coins. We don’t know whether the bags themselves have survived (they could have been made of an organic material such as textile or leather), but the corroded coins have kept the shape of their containers and I will be looking for evidence of them.

The cleaning process is fine and detailed work

The cleaning process is fine and detailed work

As my job will involve excavating the hoard, knowing that there are individual bags of coins gives me a very good starting point as it means I can deconstruct the soil block bag by bag. It will be very interesting to see if the coins were bagged together for a particular reason; for example, if they were grouped by emperor or denomination.

I’ve cleaned a few loose coins already and, after stripping away the copper corrosion, I’ve found some very impressive silver surfaces (nicer than we had previously hoped!) Given the large number of coins in the soil block, I’m hoping to be able to clean as many coins as possible using chemicals such as formic acid, rather than by hand using a scalpel. I have 18 months to complete this project, so time is of the essence.

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

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

Initial estimates put the number of coins at around 30,000. After having excavated the block a little since then, guesses about the maximum number of coins in the hoard have decreased and estimates vary between everyone looking at it. Readers of the blog are welcome to suggest their own figures – I say no more than 22,000 coins, what do you think?

Removing the tough shell of the copper corrosion layer is important not just to find shiny surfaces but also to find the detail on the coins needed for identification by my colleagues in the Coins and Medals department, Eleanor Ghey and Richard Abdy (who will be blogging about the significance of the find next week). At this early stage in the project, I’m only cleaning the coins so that they can be identified: I’m not cleaning them for display, by completely removing all the corrosion or soil; that would require more time.

Some of the coins after being cleaned

Some of the coins after being cleaned

When looking at Roman coins, specialists will be hoping to identify features on the ‘obverse’ (side bearing the bust of an emperor or an important relative) and the ‘reverse’ (side bearing representations of deities, animals, and other important Roman symbols). The subjects depicted on Roman coins varied according to emperor and coins of more than one emperor could be in circulation at any given time. On both sides, revealing enough of the ‘legend’ (the writing around the edge of the coin) is important, especially where the figure in the centre is very corroded or worn. Eleanor and Richard will also be looking closely for any mint marks on the coins (usually on the reverse) which indicate where in the empire the coin was struck, so I’ll have to be very careful when cleaning to reveal as much detail as possible.

Coins identified thus far have shown a real mix of the many Roman emperors of the third century AD (it was such a politically unstable time that many of them only got to reign a few years): Septimius Severus (AD 193-211), Gordian III (AD 238-249), Philip I (AD 244-249), Decius (AD 249-251), Trebonianus Gallus (AD 251-253), Aemilian (AD 253), Valerian I (AD 253-260), Gallienus (AD 253-268) and Postumus (AD 260- 268).

The Roman Baths Museum hopes to purchase the hoard and eventually display it to the public. It’s fantastic to know where the hoard might ultimately end up, and I’m working closely with curator Stephen Clews at the Roman Baths.

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

If you would like to leave a comment click on the title

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

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