Wiltshire Conservation Service

The conservation of Pitt Rivers archaeological models

The conservatin of Pitt Rivers archaeological models from 1890’s

Part 4

Watch our conservation video:
http://www.youtube.com/watch?v=9S1UpsOW5ec

An Aim Pilgrim Trust Conservation Project

This year, Salisbury Museum was awarded a grant from the AIM Pilgrim Trust Conservation Scheme to conserve the models. As these four models are so heavy and fragile, the Wiltshire Conservation Service moved some of its equipment to create an conservation laboatory at the museum and opened the doors to the public.

Conservation exhibition hall

At many museums there is only ever enough space to display a small proportion of the collection at any one time. These models are very large and although they provide a significant resource, they do take up a good deal of space within a gallery. To make the most of the gallery space, smaller examples of Pitt Rivers’ models have been on display.  By conserving these large models today, the Conservation Service will ensure that they will be protected and remain in good condition for the future.

The Pitt Rivers excavation models

The four Pitt Rivers models depict excavations at Cranborne Chase

Rotherley: a Romano-British settlement excavated by Pitt Rivers in 1886-7

The model of Rotherley is made of solid wood, whereas the other three are made of plaster of Paris supported by a wire frame. The largest model, the Woodyates hypocaust measures over a metre long and takes 6 people to lift!

Wansdyke

Wansdyke: a bank and ditch earthwork probably dating to the C5th AD, excavated in 1889•

Woodyates Hypocaust: part of a Roman settlement, 1889-90

Woodyates Hypocaust: part of a Roman settlement, 1889-90

Bokerley Dyke a bank and ditch earthwork possibly of late Roman date, excavated in 1890

Bokerley Dyke a bank and ditch earthwork possibly of late Roman date, excavated in 1890

Condition of the models

The 3-dimensional model of Bokerley Dyke, for example consists of a wooden frame filled with plaster which has been painted to show details of the site and its contours. The model is dirty and dusty, with heavy deposits over much of the surface and cobwebs evident in some areas.

Dirt and dust has built up on the objects over time and in some cases, this has changed the colour of the models and stained other areas.

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The wooden structure of the models has split and cracked in many areas. Wood shrinks and expands, reacting to the levels of humidity in the atmosphere. As the wood expands, this can force it to break and split giving it an uneven, damaged surface.

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Where other materials, such as paint or plaster are attached to the wood, the uneven surface puts a strain on the paint; stretching or crushing it until the paint or plaster cracks and breaks off. Some fragments of paint or plaster have fallen off and been lost.

Woodworm

Three of the models have been attacked by woodworm. These are insect larvae, which eat their way through the wood and form complex tunnel systems inside the structure. Woodworm thrive in damp environments. If left untreated, the infested wood can be so badly damaged that it will crumble away completely.

Why is conservation necessary?

Our conservation treatment will help to make sure that the models survive so that future generations can see them. Without conservation treatment, the models would continue to deteriorate. The woodworm infestation would weaken the wooden frames to the point where they could collapse. The chips and paint loss mean significant details are lost. The surface dirt, dust and stains make the models harder to understand and appreciate for their craftsmanship and information.

Treatment Proposal:

  • Clean the wood and painted plaster to remove dust, dirt and staining
  • Consolidate areas of flaking paint
  • Adhere the separated fragments of plaster and paint
  • Fill areas of missing plaster where necessary for structural stability
  • Treat the woodworm infestation to prevent further structural damage

Conservation treatment

All solvents, adhesives and techniques were rigorously tested in the laboratories before treatment commenced to ensure that no ill effects would occur to the models. Solubility tests were carried out on paint samples and the suitability of each adhesive in terms of bond strength, appearance and penetration were assessed.

Dry cleaning of the model surface

Stable areas of the surface were dry cleaned first with a museum vac and soft brushes to removes loose dirt and debris.

Smoke sponge cleaning

The stable surface areas were then cleaned with smoke sponge (vulcanised natural rubber) to remove more ingrained deposits of dirt and dust. Any smoke sponge debris was removed with a museum vac and soft brush.

 

 

 

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Model – partially cleaned

 

Consolidation Consolidation1

Fragile flaking areas of paint were consolidated with an acrylic solution with distilled water.

Plaster and Japanese tissueAreas of exposed plaster were stabilised using a facing of Japanese tissue adhered with acrylic adhesive. Areas of unsupported plaster have been stabilised by filling underlying gaps using Japanese tissue and injecting a acrylic solution with distilled water.

Woodworm

Areas affected by woodworm infestation where cleaned with a museum vac and soft brush to remove any loose frass from the infestation. These areas where then sprayed with a water-based insecticide.

Why aren’t the models going on display?

Made-to-measure storage crates are being constructed for the models so that they are protected from the environment and pests which will prevent any further damage happening to them in the future. The bespoke crates will make it much easier to manoeuvre the models around the museum, without causing further damage.

For more information:

Visit our website: http://www.wshc.eu/our-services/conservation.html

Or contact us: conservationartifacts@wiltshire.gov.uk  Tel. 01279 705500

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The Pitt Rivers Archaeological Models

The Pitt Rivers archaeological models from 1890’s

Part 3

Watch our conservation video:

Pitt Rivers and the archaeological excavations on his estate

A retired General, Augustus Pitt Rivers inherited Cranborne Chase in 1880. Cranbourne Chase spanned over 26,000 acres across two counties, Dorset and Wiltshire. The estate contained a wealth of archaeological material from the Roman and Saxon periods and this land provided the perfect area for Pitt Rivers to investigate unspoiled archaeological remains.

 A systematic approach

Pitt Rivers excavated Cranborne Chase from the mid-1880s and whilst many previous antiquarians had been attracted to burial mounds and their beautiful treasures, Pitt Rivers was interested in a wider area of investigation. His most important innovation was to collect, record and catalogue all the artifacts, not just those most decorative treasures which were admired by his contemporaries.

His approach to studying and recording the archaeology was highly methodical. He was the first to thoroughly document the stratigraphy and position of finds. On the Cranborne Chase estate, Pitt Rivers focused on the excavation of settlements and examined all the Roman and Saxon artefacts, producing illustrations. The discovery of pottery sherds for instance was indicative of everyday life and a subject worthy of study.

Pitt Rivers also published his findings and illustrated his reports. By the standards of the time, Pitt Rivers was systematic in his approach to gathering information and his records are extensive. He is widely regarded as the first scientific archaeologist to work in Britain and archaeologists to this day acknowledge his work and legacy.

Model of Woodyates Hypocaust (1888-90)

Model of Woodyates Hypocaust (1888-90)

3-dimensional archaeological models

Pitt Rivers was inspired to improve upon his 2-dimensional plans with 3-dimensional models of his excavations. The archaeological models which survive today in the Salisbury and South Wiltshire Museum are made from wood, wire and plaster of Paris.

The detail, scale and accuracy of the Pitt Rivers archaeological models is extraordinary. He marked where almost every object was found…

Model skeleton, created by Pitt Rivers

A model skeleton, created by Pitt Rivers from the Woodyates Hypocaust model: part of a Roman settlement, 1889-90

Pitt Rivers displayed many of these models when he opened a museum on his estate and today, the majority of the collection (approximately 22,000 objects) is held at the Pitt Rivers Museum at the University of Oxford.

Salisbury and South Wiltshire Museum

Salisbury and South Wiltshire Museum acquired a collection of artefacts, archaeological models and manuscripts called the Pitt Rivers Wessex Collection in 1975. The four large archaeological models from the collection had been in storage for over 30 years and had not been accessible to the public.

This year, Salisbury Museum was awarded a grant from the AIM Pilgrim Trust Conservation Scheme to conserve the models. As these four models are so heavy and fragile, the Wiltshire Conservation Service moved some of its equipment to create an conservation laboatory at the museum and opened the doors to the public.

Conservation exhibition hall

The Wiltshire Conservation Service moved some of the equipment into Salisbury Museum to create a conservation laboratory and exhibition.

At many museums there is only ever enough space to display a small proportion of the collection at any one time. These models are very large and although they provide a significant resource, they do take up a good deal of space within a gallery. To make the most of the gallery space, smaller examples of Pitt Rivers’ models have been on display.  By conserving these large models today, the Conservation Service will ensure that they will be protected and remain in good condition for the future.

More posts to come……

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Uncovering the Mysteries of a Bronze Age Burial

This is the second year Wiltshire Conservation Service has taken part in Day of Archaeology. This year I thought I’d blog about the work I’ve been doing on an amazing Bronze Age cist burial.

The burial cist was excavated in August 2011and was located on Whitehorse Hill, northern Dartmoor, on land owned by the Duchy of Cornwall.   The work was carried out by archaeologists from the Historic Environment Projects Team, Cornwall Council, led by Andrew Jones, with assistance from English Heritage (EH) and Plymouth University specialists.

Cist in situ

The cist was first discovered over 10 years ago when what appeared to be its end stone fell out of the peat mound which had been concealing it.   Since that time the peat has slowly eroded away from the sides and the top of the peat mound and after several attempts to protect the cist, a Scheduled Monument, the decision was taken by the Dartmoor National Park Authority and English Heritage to excavate it in order to recover any surviving archaeological and environmental information before the site and its context were lost.  This was the first excavation of a Dartmoor cist for nearly one hundred years.

During the late afternoon, three days into the excavation, the stones of the cist were dismantled and the large cover stone (measuring 0.8 x 0.6m) removed.  This revealed a burial deposit lying in situ on the base stone of the cist. Visible remains included bone fragments, a shale bead and what appeared to be hair or fur. Two sharpened wooden stakes were also discovered outside the cist, one lying horizontally against one of the side walls and the other still vertically placed into the peat against one of the end stones.

Located within peat at 600m altitude on one of Dartmoor’s highest tors, the cist offered high potential for good preservation of any remaining contents. It was at this point that I was contacted to carry out a microexcavation of the cist – little did I know the extent of what would be found inside!

The level of preservation inside the cist has been fantastic and the objects I have found have far exceeded all our expectations. The occupant of the grave was cremated and the bone wrapped inside an animal pelt. Grave goods include a woven band with tin rivets, a basketry bag containing a flint, two sets of wooden studs and nearly 200 shale, amber and tin beads. There is also an object made from leather and woven plant material which is so far proving to be a bit of a mystery. The craftsmanship that has gone into making these objects is pretty mindblowing and it is clear that their owner was someone of importance.

Back of woven bag (flipped over)

The project team are gathering the results of analysis that has been carried out and we hope to be able to share the results later on this year. Of particular interest is DNA analysis of the pelt, which we hope will reveal the species of the animal skin used to wrap the cremation. Meanwhile, I have been working on the conservation of the objects which is still ongoing. Today I’ll be working on cleaning and consolidating the woven band and checking on the pelt, which is being dried under controlled conditions.

Removing fur-hide layer2

The project has provided an opportunity not only to try and discover who the occupant of the grave might have been, but to also give a unique insight into life in the Early Bronze Age and I am extremely privileged to have been involved. The objects will be going on display at Plymouth City Museum and Art Gallery in 2014 so check their website for more details www.plymouthmuseum.gov.uk. I’ll also be posting updates on Twitter @helenwcons and on our blog www.wshc.eu/blog.

The project was jointly funded by the Dartmoor National Park Authority (DNPA) and English Heritage, with contributions from a number of other local funders.