From Michelangelo to mirror caskets, our conservators continue the centenary celebrations for the Departments of Collection Care and Scientific Research by sharing the projects they're working on.
100 years of science and conservation: recent conservation highlights
2020 marks 100 years since the creation of the 'Research Laboratory' – a space for developing and conducting scientific research and conservation on the British Museum collection, which would later become the Departments of Scientific Research and Collection Care. Continuing our centenary celebrations, we highlight some of the recent success stories from our conservation teams, reflecting the diversity and range of their work.
The variety of objects in the British Museum collection offers our conservators the opportunity to work in specialised areas within the inorganic materials (stone, metals, ceramics, glass); organic materials (wood, textiles, plant and animal materials, plastics); pictorial art (graphic art on paper, photographs, papyrus, conservation mounting) and preventive (reducing the rate of deterioration in objects) teams. These projects highlight how conservators use their in-depth knowledge of materials and expert hand skills, plus how they utilise both low-tech solutions and high-tech equipment in their work.
Bringing the Sherborne cartonnage back to life
One of the challenges facing conservator Verena Kotonski in the organic materials studio when we re-open is a newly acquired Ptolemaic period Egyptian coffin. Excavated in 1907 during the First Archaeological Survey of Nubia, the location and context of the coffin’s burial are well-documented. However, its whereabouts following excavation remained mysterious until recently, when it was realised that it was the coffin acquired in 1915 by Colonel Wingfield Digby of Sherborne Castle, Dorset, and displayed at the Castle until 2000. In 2018 it came to the British Museum, and is the only example of this type of coffin in the collection.
Made of painted cartonnage – layers of linen cloth glued together and covered with paint – the coffin had deteriorated badly after years of standing upright in damp conditions. The cartonnage had slumped, with textile layers separating and damage to the paint layers occurring – it looked almost beyond repair.
Thanks to Verena's ministrations, both parts of the coffin are now being gradually brought back to their original shape. Sat inside polythene humidity tents, a combination of the controlled introduction of moisture and application of just the right amount of pressure enables Verena to manipulate the material. An earlier reinforcement of cardboard, glued to the inside of the coffin base, was exacerbating the distortion and is being painstakingly removed. The complex task is made all the more tricky when the presence of mould means that Verena must work with suitable protective equipment.
Look out for a forthcoming film following the conservation treatment. Following the completion of conservation, a detailed description and images of the cartonnage coffin will also be made available on Collection online.
This work is funded by the John S Cohen Foundation.
Combining 'traditional' and 'modern' in conservation
The Ceramics, Glass and Metals Conservation Team combine a variety of skills and use a range of materials and techniques which can be adapted to both ancient and modern objects. One example is the use of old shimbari technique on metal objects. The technique is a traditional Japanese method for restoring lacquer objects. By surrounding an object in a three-dimensional frame, padded bamboo or plastic sticks can be modified to apply pressure to the surface of unusually shaped objects for extended periods of time.
Metals conservator Rachel Weatherall used the shimbari technique on a silver mirror casket to re-adhere silver. The silver on the exterior of this mirror casket was cracked and lifting in several places, and the underlying wood and lacquer substrate (base layer) was very fragile. She injected consolidant under the lifting areas with a syringe and could apply just the right amount of light pressure to fix the silver in place without damaging the wooden structure beneath.
This technique is also useful when it is necessary to apply significant pressure for a long period of time, as in the case of a bidriware (a type of metal handicraft) bowl, which had loosening silver inlays. The silver was so thick and hardened that it would lift up again while the adhesive applied was setting. Using a shimbari frame and thick bamboo sticks, it was possible to hold the silver in place for several days to allow the adhesive to set.
Bigger objects, different challenges
The work of conservators in Stone Conservation can sometimes take several months to complete because of the sheer size of the objects. Karen Birkhölzer worked for more than 220 hours to conserve this pentelic marble sarcophagus with the scenes of the life of Achillies for our 2019 exhibition on Troy.
Karen worked with two other conservators, Tomasina Munden and Francesca D’Anellio on the sarcophagus. Francesca came to the Museum for work experience as a recent conservation graduate. The Conservation Section regularly hosts students in placements which are a great way for them to get hands-on practice while learning and collaborating with experienced conservators.
When we re-open, the preventive team will continue the process of moving the collections from the Museum’s satellite sites at Blythe House and Orsman Road, to the purpose built storage facilities at the World Conservation and Exhibition Centre in Bloomsbury. The movement of these objects means the preventive team can ensure that each item is correctly supported with conservation-grade materials, which will reduce the stress and strain on vulnerable edges and remove unnecessary folds from fragile textiles.
The WCEC has a dedicated air conditioning system so it can provide a stable environment for the collections in terms of humidity and temperature. This is vital as many materials, particularly wood, expand and contract with variations in humidity – similar to the way in which metals react to changes in temperature. The move to the central site will also enable greater access and make it easier for both British Museum staff and external experts and researchers to see these collections.
The preventive team monitors the environment across the British Museum estate using sensors that send measurements of the humidity and temperature to a central system so that all areas can be seen from a computer. There are over 700 sensors that each send information back every 15 minutes, and Fabiana and a team of conservators are now monitoring these from home. These sensors also need to be calibrated once a year to ensure that they are providing accurate information. Each sensor must be exposed to three different salts that have defined levels of humidity, and then can be individually adjusted to correct any ‘drift’ in the readings.
Getting up close and personal to a masterpiece
Michelangelo’s cartoon Epifania was, for many years, on display in the Prints and Drawings gallery. The opportunity to take a much closer look came in 2018 when the unframed cartoon came into the Western Art on Paper studio for examination and essential treatment. The first priority was to remove the cartoon and its 19th-century paper backing from the heavy wooden panel, on which it had been mounted for some time before its acquisition in 1895.
An extended period of examination under different lighting and magnification, alongside new techniques such as digital mapping and 3D scanning, has given conservators a way to describe in detail the manufacture, history and condition of the cartoon for the first time. As conservation is still underway, we look forward to sharing this information when the cartoon is back on display.
This work has been funded in memory of Melvin R Seiden.
More science and conservation stories
We’ll be sharing more stories and revealing new work from both the Department of Scientific Research and the Department of Collection Care over the coming year. Stay tuned to find out more about the amazing work that goes on behind the scenes here at the Museum to help us care for the collection and continue uncovering stories from history.
Read more about our recent Scientific Research success stories.