Conservation

From a block of soil...

on Tuesday, 05 July 2016. Posted in Archaeology, Conservation

The conservation team are celebrating this week as we have completed work on a beautiful and exciting project. Conservation of the stunning finds excavated from Bognor Regis by Thames Valley Archaeological Services in 2008 has come to fruition. The items form part of an unusual burial assemblage along with an iron ‘bed’ frame and sword and are thought to originate from the late Bronze Age/ early Iron Age.

Taking block of soil for x-ray

The finds first came to us in the unassuming form of a large soil block, this was too large to x-ray at our labs so was transported to a local hospital where x-rays revealed a large amount of intricate metal latticework and a helmet.

X-ray of soil block from hospital

The soil block was carefully excavated, layer by layer, revealing the spectacular nature of the copper alloy items held within. The helmet and latticework were extremely fragmented and fragile, the helmet was split in half and part of the lattice was adhered to the helmet with corrosion products.

Conservation of finds unearthed by a badger

on Saturday, 16 April 2016. Posted in Archaeology, Conservation

You may remember the image of a group of ceramic sherds from one of our previous blog posts. Following reconstruction of the vessel we now have true understanding of the magnificence of the objects found. Watch a time-lapse video showing elements of the reconstruction of the vessel.

 

Conservation treatment involved a task like a jigsaw puzzle without a picture. The size, shape and colours of the sherds were used to determine their original location within the urn. Due to the uneven firing of the vessel and areas of burning caused by hot ashes being placed inside the vessel some areas were easier to piece together than others.

When the collared urn was originally manufactured ceramic technology was in its infancy with the kilns used never reaching the temperature required to permanently set the clay in position. During the time the vessel was in the ground, moisture from the surrounding earth also weakened the under-fired structure. This effect, on top of the unconventional excavation method, has meant that the overall shape of the vessel has become distorted.

Before reconstruction the edges of each fragment were strengthened by allowing a weak adhesive to be drawn into the rough surface to hold the loose and sometimes crumbling structure together. The adhesive is well used in conservation and has been developed and tested to ensure that it is long-term stable meaning it will not degrade causing damage to the original fragments of the vessel.

A stronger concentration of the same adhesive was used to adhere the fragments in position, small strips weak masking tape were used to hold the fragments in position as they dried. As the vessel was so large the reconstruction had to be undertaken in stages to ensure each level of fragments were securely in position and ready to support those placed on top.

Remarkable finds from an unusual source

on Friday, 22 January 2016. Posted in Archaeology, Conservation

A large box, filled with Bronze Age finds recovered in Netheravon, was brought to the conservation lab here at the Wiltshire and Swindon History Centre. The objects were covered in moss and smelling rather musty, this however was explained when we were told that the finder of these objects wasn’t an archaeologist but a badger. Deciding to make its home in a convenient mound, the badger inadvertently unearthed finds of a similar style and importance to those found with the nearby Amesbury Archer.

Selection of ceramic sherds

The group of finds include sherds from a large ceramic urn, various bone and antler tools, 2 metal objects (one a serrated blade and the other is still a complete mystery) and most significantly a copper chisel with the decorated bone handle still attached.

Copper chisel with bone handle

The owner of these objects was probably an archer as the finds included a wrist guard used for protection when shooting a bow and stone tools used for straightening arrow shafts.

Wrist guard and shaft straighteners

As the objects were damp when they were unearthed we needed to let them slowly dry out before conservation could begin. This is particularly necessary for the bone and antler finds, as with all organic material, bone and antler swell and contract depending on the moisture content of the object and surrounding air. If the objects were to dry out too quickly then cracks and other damage may be caused.

The conservation team turn detective! Part 2

on Thursday, 29 October 2015. Posted in Conservation

Curing the salt contamination in a pair of Imari vases. A serial conservation mystery, episode 2

In May we discovered that the Imari vases which had been brought to the lab from Wilton House were suffering from a case of salt contamination http://wshc.eu/blog/item/the-conservation-team-turn-detective.html. The salt had caused large cracks up the side of the vases reducing their structural stability and causing loss of some fragments and areas of glaze.

Developing a treatment

Removing salt from an object is best completed by dissolving the salts into water and removing the contaminated water from the vase taking the salt with it. If not all the contaminated water is removed during the treatment some salt will remain and the process of crystallisation will begin again, causing further deterioration.

To try out our treatment options we needed to create some test patients with similar symptoms to the Imari vases.

Undertaking clinical trials

The test patients were contaminated with salts from the base up to simulate the issue with the Imari vases.

Due to the size, weight and fragile nature of the vases treating only the affected area would be the ideal solution. We tested using a poultice made from blotting paper, cartridge paper and distilled water.

To use a poultice you apply a thin layer to the affected area and allow to dry. As the water evaporates from the surface of the poultice the salty water in the centre of the pot is drawn out and the salts are deposited in the poultice. The dried poultice can then be removed taking the salt with it.

The clinical trial turned out to prove the treatment was not effective, instead of evaporating from the poultice some of the water was drawn into the test pot and evaporated from the exposed rim leaving the salts behind.

It was clear that a plan B would have to be developed....

The Conservation Team Turn Detective!

on Friday, 22 May 2015. Posted in Conservation

Finding the cause of deterioration in a pair of Imari vases. A serial conservation mystery, episode 1

In the conservation lab we have two very large and impressive-looking vases. The vases from Wilton House, Salisbury have come to the conservation lab to be repaired as they are both structurally unstable. The conservation team turned detective in order to discover what was causing the instability. In the first episode of our conservation blog, you’ll find out how the conservators uncovered the symptoms and solved the case.

The patients

The vases are late 17th Century examples of the popular Japanese style ‘Imari’ identified from the distinctive decoration of cobalt blue under-glaze and gold and red over-glaze. This style of Japanese porcelain was produced as export for the Western market, indicated by the style sharing its name with the Japanese port from which it was transported: Imari, Saga.

The symptoms

The vases have large cracks running from the base, nearly ¾ of the way up the sides. The cracks weaken the structure and cause the significant instability. Along the edges of the cracks and round the base of the vases are missing areas of decoration and glazing. As the vases are no longer in one piece, they are not safe to display in this condition. While the cracks remain, these vases continue to be at risk of breaking apart.

 

The suspects

Although the symptoms of deterioration could be clearly identified, their cause remained a complete mystery. The conservation team could treat the symptoms. We could fill the large cracks and repair the glazing but without discovering the cause of the damage and finding a suspect, we would be taking a big risk. Further deterioration could occur in the future and the vases become irrevocably damaged.

Celebrating the 8OOth anniversary of the Magna Carta

on Monday, 16 March 2015. Posted in Conservation

The Wiltshire and Swindon History Centre have been preparing an up-coming display to mark the 800th anniversary of the Magna Carta, which is to be held at Lacock Abbey.

The display will feature three original documents: a facsimile of the 1225 Magna Carta presented to Lacock abbey after the original charter was presented to the nation; and two enrolled copies of a 1300 confirmation of the charter in the archives of the marquis of Ailesbury of Savernake and Marlborough borough which are held at the Wiltshire and Swindon History Centre.

These documents will be supported by a display illustrating life in Wiltshire in the 13th century and the impact of Magna Carta. Copies of documents will include images from the pageant in 1932 to celebrate the 800th anniversary of the founding of Lacock abbey.

The exhibition will be at Lacock Abbey in June and July and then at the Wiltshire and Swindon History Centre. The screens will then be available for display around the county.

A project to conserve and display 13th Century documents for the Salisbury Cathedral Magna Carta exhibition.

The Archive conservation team have recently been working on a project to conserve and display four 13th Century parchment documents for the 800th Anniversary of the Magna Carta exhibition at Salisbury Cathedral.

The documents are: a charter, an indulgence, a declaration of canonical obedience and an agreement of tithes.

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