Amgueddfa Blog: Conservation

There are times in life when a problem and its solution come together seamlessly.

The problem – one which every museum faces: cryptic causes of deterioration of stored objects.

The solution: investigation using the latest chemical analyses.

One step better: to combine this analysis with the mission of museums – inspiring people – and undertake the investigative work with full public engagement.

Like most museums, National Museum Cardiff has the task of slowing down corrosion to preserve collections. Think of your family silver tarnishing and you know what I am talking about. Multiply this by hundreds of thousands of metal objects in our collection and you understand the herculean task we face when we come to work every day.

Like most museums, we do not have much equipment to undertake complex chemical analyses. So when we want to investigate the magnitude of potential sources of corrosive airborne substances in our collection stores, we often work in partnership with academic institutions.

SEAHA is an initiative between three universities with industry and heritage partners to improve our understanding of heritage science. Heritage science is multi disciplinary and includes experts with chemistry, imaging, IT, engineering, architecture and other backgrounds. One of SEAHA’s amazing facilities is a fully equipped mobile laboratory. We submitted an application last year for the mobile lab to come to Cardiff which, amazingly (there is much demand for this vehicle), was approved. Last week, staff and postgraduate students from University College London, one of SEAHA’s academic partners, visited National Museum Cardiff.

The Mobile Heritage Lab was at the museum for two days. During this time, we assessed environments and pollutants in collection stores and in public galleries. We undertook this work with full involvement of our museum visitors. The mobile lab was parked next to the museum entrance where we encouraged our visitors to explore the on-board analytical equipment. UCL staff and students were at hand to explain how science helps us preserve heritage collections, for example how UV fluorescence is used to explore paintings.

We received a visit by A-level students from Fitzalan High School in Cardiff in the morning. The students were especially interested in chemistry. After a quick introduction, we gave the students an ultra-fine particle counter to produce a pollutant map of the public galleries at the museum. The students used this equipment to measure ultra-fine dust inside and outside the museum. We are still analysing these data, but the early results indicate that the museum’s air filtration system is doing a good job at keeping dust out of the building. This is important because the gases associated with ultra-fine particles (for example, SO2) can damage paper and other organic materials.

We also measured concentrations of volatile organic compounds (VOC) in collection stores and found that levels were higher inside drawers in the Entomology collection than in the store itself; this is important in the context of entomological pin corrosion. We managed to confirm that work we undertook recently to reduce the levels of VOC in the museum’s Mineralogy store had been effective and successful. In addition, we used a thermal imaging camera to check whether relatively high temperatures in a display case are caused by heating pipes in the wall behind the case, or by in-case lighting.

The Mobile Heritage Lab’s visit provided us with an opportunity to answer some important questions about the way we care for the museum’s collections. At the same time, we managed to teach students the practical applications of investigative science and analytical chemistry. Lastly, we spoke to many museum visitors about the role played by science in the preservation of heritage collections. We are extremely grateful for the fruitful partnership with SEAHA and hope to collaborate on additional projects in the near future. For example, there are some interesting questions surrounding the deposition of different types of dust which we discussed over a beer on Thursday evening. Watch this space as multi-disciplinary heritage science is becoming ever more important for answering questions of collection care and preservation. Museums are best placed to working in partnerships on important scientific questions while achieving public impact by explaining to a wider audience how science works.

Find out more about Care of Collections at Amgueddfa Cymru - National Museum Wales here and follow us on Twitter.

Over the last few months you may have seen the Saving Treasures; Telling Stories team on social media using the hashtag ‘Finds Friday’, where we’ve been showcasing some of our wonderful treasure and non-treasure items recorded by the Portable Antiquities Scheme Cymru.

This month we’d like to focus on two special finds from Wales: The Abergavenny Coin Hoard and a prehistoric feasting site in Llanmaes.

Why these two finds?

Both have been nominated in a nationwide competition, held by the British Museum and The Daily Telegraph, to search for the nation’s favourite treasure item from the ‘Top 20’ list.

2017 marks the 20th anniversary since the passing of the 1996 Treasure Act and items on the ‘Top 20’ list highlight some of the most important treasure discoveries since the Treasure Act.

We might be a tad biased towards which ones we’ll be voting for, but we want to share the history behind these finds as they really do have a story to tell, or in the case of Llanmaes, an enigmatic mystery as to what was actually happening at the site. You can read about the 20 items by clicking this link, and don't forget to vote!

This is the logo for the '20 years of Treasure' competition, run by the British Museum and the Daily Telegraph.
20 Years of Treasure logo

Llanmaes

Our first nomination on the ‘Top 20’ treasure list is a site, rather than a single group of objects. The discovery is a prehistoric feasting place and settlement, uncovered in Llanmaes, in the Vale of Glamorgan.

This important site was discovered following the reporting of a potential treasure find by two metal detectorists in 2003, and excavation continued for the next seven years by archaeologists from the National Museum of Wales, assisted by students from Cardiff University and local volunteers.

The story behind Llanmaes

The earliest remains on the site, dating to about 2150-1950 BC, are the cremated remains of an adult male, which were buried in an urn. It seems that this burial provided the focus for later settlement, which yielded treasure objects such as a gold bead. One mystery object in the shape of a great white shark’s tooth has left archaeologists puzzled. We’re not too sure where it came from or why it was left there!

By the beginning of the Iron Age (about 675 BC) this settlement had been abandoned, but the site continued to be the focus of human activity in the form of feasting, which left behind an extensive midden deposit. This is the first known example from Wales, of a class of middens representing remarkable accumulations of cultural material gathered by communities at the beginning of the Iron Age. This has revealed an extraordinary prehistoric feasting mound, containing thousands of pig bones, further feasting vessels, bronze cauldrons, pottery and axes.

Unexpectedly, nearly three-quarters of the animal bones were from pigs – a far higher proportion than is usual for such deposits, and, even more remarkable is the discovery that the majority of the pigs’ bones were from the right fore-quarter of the animal. Similarly, some of the axe-heads are of a type associated with parts of northern France, so it seems as though people were converging on Llanmaes during the Early Iron Age from a wide area to engage in cultural activities which had clear rules and accepted practices.

Feasting seems to have come to an end at the site during the Roman period, when changing cultural practices made the earlier rituals less appropriate, but evidence of continued Roman occupation suggests that it still held meaning for local people into the 4th century AD.

The community at Llanmaes were closely involved with the excavations over the years, and the National Museum’s Archaeology department brought in a number of school groups to work with artists on creative responses, such as performances, inspired by the site.

Feasting and pig bones from Llanmaes (Credit: Amguedffa Cymru)

A prehistoric site is being excavated
Llanmaes excavation

Abergavenny hoard

In April 2002 three metal-detectorists had the find of their lives in a field near Abergavenny, Monmouthshire where they found a scattered hoard of 199 silver pennies.

The Abergavenny hoard is the earliest Norman hoard from Wales and provides a vivid picture of monetary circulation in the Welsh March in the 1080s CE. It includes 130 coins of the Anglo-Saxon king Edward the Confessor (1042-66) and 69 coins of the Norman king William the Conqueror (1066-87).

Where did they come from?

Norman incursions into Gwent (present-day Monmouthshire) had followed hard on the heels of the conquest of England by Duke William in 1066 and they brought with them the habit of using coins.

The 199 silver pennies provide a rich mixture of issues of Edward the Confessor (1042-66) and William the Conqueror (1066-87); there are coins of 104 moneyers from 36 mints, with Hereford prominent.

The coins had been lost or hidden in a cloth bag, after about 1080 CE and for most people living in that time they would have represented several months’ pay. However, the lack of positive archaeological context makes it impossible to judge whether the coins had been concealed deliberately or were simply lost. We shall probably never know quite why these coins ended up in the corner of a field in Monmouthshire but, as well as expanding our knowledge of the coinage itself, they will cast new light on monetary conditions in the area after the Norman Conquest.

And there we have it, our two treasure finds on the ‘Top 20’ treasures list.

The online voting continues until May 15th, and you can vote for LLanmaes or the Abergavenny Hoard by following this link:

http://www.telegraph.co.uk/wellbeing/mood-and-mind/treasure-20-vote-favourite/.

Our collaborations with Cardiff University in the area of heritage science continue to grow. Just before Easter, Daniel Griffiths from the School of Engineering contributed towards our goal of developing monitoring tools for use by museum conservators.

One of the routine tasks of conservators is to keep an eye on the condition of items stored in museums. Being responsible for looking after Amgueddfa Cymru - National Museum Wales’ five million objects, the team of less than 20 the conservators have their work cut out. In addition to the sheer number of objects in need of monitoring, for some categories of items there are currently issues with keeping adequate records for comparison with future condition assessments. We also want to objectivise the entire process to enable easier comparison between assessments undertaken at different times or by different people.

Presently, changes to collection items (if any) are detected by visual assessments and recording these in a text form, often supplemented with photographs. If such items are small and prone to chemical reactions, the results of which are difficult to describe, condition assessments are very difficult to undertake.

How do we make things easier, quicker and more objective? Daniel, a student in engineering, undertook a pilot study to create an overview of our options for non-invasive damage testing in geological specimens (specifically, in minerals). Some testing methods – such as acoustic emission, ultrasound, and X-ray and micro magnetic resonance imaging – were discounted early on in the project for various reasons. Any further techniques Daniel considered are based on imaging or scanning, grounded in the assumption that most damage to minerals is visible as changes in shape, integrity or colour.

Initial thoughts on using artificially aged pyrite were replaced in favour of CAD-designed and 3D-printed models of ‘crystals’: one set ‘undamaged’ and a second ‘damaged’ set with deliberately introduced yet precisely known ‘decay features’, such as holes and cuts. Daniel then scanned or imaged these models and compared the results for speed, ease of use, cost effectiveness and accuracy of recording of ‘decay’.

The best results were obtained with the Artec Space Spider, a handheld high-resolution 3D scanner based on blue light technology with easy-to-use software. The downside of this technique is the high purchasing cost of this instrument and software. Mobile phone technology, which was one of the comparative techniques, is not yet evolved enough to provide useful (i.e., good image quality, faithful recording of defects smaller than 5mm diameter) results.

The results of this study are encouraging because they provide us with a good foundation for future development work. There are questions about the faithful recording of colour, especially of reflective crystal surfaces, and combining features of storage, processing and analysis of images through one single computer program.

Daniel was supervised by Prof Rhys Pullin and Dr John McCrory from Cardiff University’s School of Engineering. We thank both of them for their support and cooperation in this project.

Find out more about Care of Collections at Amgueddfa Cymru - National Museum Wales here.

We wrote of dust before, for example here and here. The museum is like your home, dust gathers everywhere. Unlike my own house though, the museum is very, very big. The museum's dust problems are correspondingly large.

Last year a student from Cardiff University, Stefan Jarvis, undertook a dust monitoring project in the museum. Stefan was studying for an MSc in Care of Collections, which is a subject very close to my heart. Stefan is also the author of one of our guest blogs. Stefan placed a large number of dust traps around the museum building: in stores and exhibition galleries. You may be familiar with some of the galleries he investigated: our Geology gallery with the dinosaurs, the current “Wriggle” exhibition on worms, the Whale gallery and the Organ gallery where we display some of the largest paintings in the museum.

Collecting dust is really easy: prepare a sampler. Leave it out in a suitable location. Wait. For. Four. Weeks.

Once Stefan had gathered some dust he analysed the samples: he identified each particle under the microscope and determined where they all came from. This is where things started getting really interesting. For while undertaking scientific investigations are often laborious and involves much routine work, the results are often extremely illuminating.

This is what Stefan found:

  • More dust accumulates in areas of high traffic (i.e., many people walking past).
  • More dust accumulates at low levels (the closer you get to floor level the more dust you will find).
  • Dust composition differs between spaces. For example, most dust fibres in a library store are paper fibres, while most fibres in public galleries are textile fibres, hair and skin.
  • We found biscuit crumbs on the dust samplers in two galleries. This indicates that food was being consumed in these galleries.

Now, we love having people in the museum. In fact we undertake some of our collection care work during museum opening hours so that you can see what we are up to a lot of the time. Therefore, we are happy to accept that visitors always leave us a little reminder that they have been, in the form of a few dust particles. You can feel a ‘but’ coming on: but we do not encourage the eating of biscuits (or any other foodstuffs) in our galleries. Eating food in our galleries bears the risk of small amounts of food ending up on the floor, in displays, behind cupboards - or, as part of dust. Food encourages the spread of pest insects which, once they have eaten all the available biscuit crumbs, then start munching our collections. This is not something we endorse, because we try to preserve our collections for you to enjoy.

This means you can actually help us preserve the collections - by not eating in the galleries. We will be doing more work on this in the near future, by encouraging visitors to consume food in our fabulous restaurant or cosy cafe, not in galleries. In the meantime, we really do appreciate your cooperation and understanding for our no-food-in-galleries policy.

Find out more about Care of Collections at Amgueddfa Cymru - National Museum Wales here.

 

 

 

The country craft of hedgelaying is being demonstrated at Fagans National History Museum during 2017. Hedgelaying creates a stronger, thicker barrier to keep animals within fields, and provides shelter and shade for them. This year it will be combined with opportunities to try out the craft and the museum provided its first hedge-laying training courses for the public.

Hedgelaying, Pen-y-cae, Brecknockshire, c1936
Hedgelaying, Pen-y-cae, Brecknockshire, c1936

Creating fields and hedges

From the sixteenth century onwards, vast areas of open land were enclosed and turned into fields for agricultural use. Hedges were planted to prevent sheep and cattle from straying, and to separate grassland from crops. Such hedges also provided shelter, a source of food such as berries, and habitat for wildlife and fauna. Hedges were also cheaper than building and maintaining dry-stone walls.

 

The craft of hedge laying

Hedges are maintained by laying. Once the trees had grown to a certain height, they were cut and laid horizontally to form a stock-proof barrier. The cut is not made through the branch in order to allow the tree to re-grow. What is created is effectively a living fence. The work is done during the less busy winter months when there is less foliage and the tree will re-grow.

 

Welsh hedging styles

Methods of laying hedges vary in different parts of Wales. Styles differ according to how the branches are positioned, the use of stakes, and whether binding is used. Hedging is often accompanied by building banks and digging ditches. The hedges being laid this year at St Fagans are in the stake and pleach style from Brecknockshire (Powys).

 

Stages in laying a hedge, stake and pleach style.

Photographs taken in Sennybridge and Cray, Brecknockshire, 1972-73.

 

Photo of hedge cleared of dead wood and unwanted growth
Firstly the hedge is cleared of dead wood and unwanted growth

Photo of branches, known as pleachers, cut at the base of each stem and bent forward. When cut properly, they should continue to grow.
The branches, known as pleachers, are cut at the base of each stem and bent forward. When cut properly, they should continue to grow.

Photo of hedge showing pleachers woven between stakes.
The pleachers woven between the stakes.

Photo of hazel hetherings along the top bind the stakes and pleachers
Hazel hetherings along the top bind the stakes and pleachers

Photo of the hedge is trimmed and shaped to a uniform height and width.
Finally the hedge is trimmed and shaped to a uniform height and width.


 

 

Gareth Beech

Senior Curator: Rural Economy

Historic Properties Section

History and Archaeology Department