Cassy Cutulle
Objects Conservation Portfolio
UCL, Conservation Studies
2012-2013
The first year of University College London's MSc in Conservation for Archaeology and Museums program was comprised of two lecture-based components-"Conservation Materials Science" and "Conservation Processes"-to complement practical laboratory work (termed "Conservation Studies") undertaken three days out of the week. My laboratory work centered around the treatment of twelve objects, which included ceramic, clay, glass, metal, ivory, wood, stone and rubber. For each treatment, students were responsible for undertaking technical analyses, consulting with stakeholders and owners, providing appropriate justifications and options for treatments, producing detailed photographic and written documentation and constructing appropriate packaging and labels for each object by the end of the laboratory year. The summaries below describe several of the treatments I conducted during my laboratory year. Full treatment reports for the objects listed below can be provided upon request.
TREATMENT OF A MODEL WIGWAM
BEFORE FRONT BEFORE REVERSE
AFTER FRONT AFTER REVERSE
DECONSTRUCTION
After a thorough assessment of the condition of the model and the treatment options available, it was determined that the best option for improving the stability and overall condition was to undertake deconstruction to properly re-structure. This was done by detaching the birch bark panels surrounding the interior support system. The panels were held in place with vegetable fibre ties which were unoriginal to the model. The wooden base and hide were all cleaned of dust and dirt after the deconstruction process [See Images at Right].
(Above Left) Image of the Japanese tissue paper ties applied to the junction between the interior support ring and the stick-supports. These ties added stability to the the newly restructured interior support system.
(Bottom Right) Image of the Japanese tissue paper repairs being added to the rehumidified hide.
RECONSTRUCTION
The final part of the treatment included cleaning the birch bark panels with Smoke Sponge (vulcanized natural rubber) and tying them to the interior support structure. Each panel was situated on the structure and placed according to their placement in previous photographs. Tiny holes were available on each panel that had been used in the past to tie them in place. These holes were reused to tie the panels. A needle and brown thread (Williams® Linen Thread) were passed through one of the holes and around the adjacent stick support on the inside of the wigwam and through the other hole. The string was then cut and tied off on the exterior.
CONDITION AFTER TREATMENT
Following treatment, all aspects of the model have become much more stable. The stick-supports were stabilized through reconstruction, and the interior support system was fixed in place at the top and bottom, providing a more robust structure for the birch bark panels. In sum, the total condition of the object and all of its component parts were greatly improved.
MY EVALUATION
This treatment was a complex one that provided me with a range of skills, and in particular, technical skills that advanced my manual dexterity. Delicate and careful tasks like the tying of the stick-supports and the birch bark panels were both challenging and fulfilling. Additionally, the ethnographic nature of the object provided the me with a new conceptual context from which to work. Furthermore, this treatment allowed me to understand the importance and value of consistent and justified treatment work.
CONTEXTUAL INFORMATION
The model was retrieved from a native group somewhere in Central or Eastern Canada around the late 19th-century by Professor William Saunders, who worked for the Canadian government in Ottawa. It arrived in the Kew Economic Botany Collection in 1888 and was stored as an exemplary artefact. It is possible that the model was purposefully constructed as a souvenir for a non-native audience. Research showed that the structure is most likely classified as a wigwam—a specific type of housing utilised by the Eastern Woodlands Native communities.
PRE-TREATMENT CONDITION
The stability of the structure was in poor condition prior to treatment. The interior support-system was failing because the wooden stick-supports were not secured at the base or top of the structure and were falling out of place. The birch bark was also unstable because it was moving with the unstable interior supports. A piece of hide was precariously hanging by a thin string within the structure and appeared dry and stiff.
REASON FOR TREATMENT
It was requestedthat the model be conserved to ensure its future stability while in storage and on display at the Kew Economic Botany Collection. This model was also utilized for handling and research purposes, therefore improvements on the overall condition were essential. Continuous contact with Mark Nesbitt-Economic Botany Manager at Kew-aided in the development of the treatment approach for this object. Of primary concern was the structural integrity, which needed stabilization.
(Above Left) Image of the interior support system of the model immediately after the removal of the birch bark panels. Cotton tape was used to gently hold the stick-supports in place.
(Above Right) Image of the interior support system after the restructuring of the stick-supports.
STABILIZATION
First, the interior support system was restructured to restore stability to the model. To do this, it was necessary to determine the original locations of the stick-supports and restructure them accordingly. If it was not possible to determine the original location, the stick was kept in the area it was found or in a hole close to that which provided that best structural stability. After this was completed, the interior ring support was adjusted so that it was parallel to the base platform. This further stabilized the interior support system by maintaining the positions of the sticks. To increase the support, Japanese tissue paper (Tengujo white wove J1002) strips tinted with watercolor pigments and impregnated with Mowital®B30H (polyvinyl butyral) 5% v/v in ethanol were adhered at the junction between each stick-support and the interior ring.To add further stability, more tinted Japanese tissue paper ties impregnated with Mowital® B30H 20% w/v in ethanol for strength (all light brown in colour) were twisted and tied over the same areas as the previous ties adhered on [See Images at Left].
Three of the wooden stick-supports were also treated. Old adhesive was cleaned off of the join edges of one of the sticks where a previous reconstructed had occurred and Mowital® B30H 10% v/v in ethanol was used to adhere the pieces. A filling material made of Mowital® B30H 20% w/v in ethanol and microballoons tinted with dry pigments (raw sienna and burnt umber) was used to fill the void in the reconstructed stick and to enhance the stability of the reconstruction. Bark relaying was done using ethanol to break the surface tension and Mowital® B30H 5% and 10% v/v in ethanol on three of the stick-supports.
After the interior support system was restructured and fixed in place, treatment began on the animal hide. First, the hide was rehumidified in a Perspex® (polymethyl methacrylate) chamber. The hide was first placed in the chamber with a saturated salt solution and covered with polyester wadding (polyethylene terephthalate) for a period of approximately 30 minutes at 60-70 % relative humidity (RH) with no weighting to observe the changes. It was noted that the hide became more flexible and no negative effects were observed. The hide was then maintained in the chamber for three days in the same conditions with a higher RH of around 80-90% and with wooden boards adding weight to help flatten the hide slightly. After the successful rehumidification and reshaping of the hide repairs were done to the upper, torn area of the hide using Japanese tissue paper ties (Gampi Silk Tissue J626101) adhered using Mowital® B30H 5% w/v in ethanol.
(Above) Image of the model wigwam as the birchbark panels were being re-attached.
Model Wigwam
UCL Lab Numer: 8957
Photographs by Cassy Cutulle
© University College London. Images may not be reproduced.
TREATMENT OF A BRONZE RING
BEFORE FRONT AFTER FRONT
CLEANING AND STABILIZATION
Prior to the cleaning of the ring, the accession number was removed with a cotton wool swab dampened with acetone. The ring was cleaned through immersion in an ethanol bath for approximately one minute and then brushed gently with brushes slightly dampened with ethanol. Powdery corrosion products were removed under the microscope using a no. 15 scalpel.
The copper alloy ring was immersed in a benzotriazole (BTA) 3% w/v in ethanol solution for twenty-four hours to complex the copper ions on the ring and prevent corrosion processes from occurring in the future. The ring was then coated with ParaloidTM B-72 (ethyl methacryalte methyl acrylate copolymer) 3% w/v in acetone to protect the BTA film and further inhibit corrosion [See Upper Right Image].The accession number was re-applied using white ink and ParaloidTM B-72 20% w/v in acetone as a base and top coat. White ink instead of black ink was used so that the accession number was more visible against the dark metal substrate
CONDITION AFTER TREATMENT
Following treatment, the ring appears stable and no new corrosion has formed.The immersion in BTA and coating with ParaloidTM B-72 3% w/v in acetone created and sealed a film on the ring which prevented new corrosion from forming.
(Above) Image of the ring after immersion in BTA and coating in Paraloid B-72 3% w/v in acetone.
MY EVALUATION
The treatment of this bronze ring greatly aided my understanding of treatment processes for copper alloys and the conservation approach to cleaning archaeological metal objects. The delicate removal of the thin corrosion products with a scalpel provided me with mechanical skills critical for the treatment of metallic objects and conservation in general. The use of X-ray images and pXRF data demonstrated the value of such analyses before treatment. Overall, my knowledge of metals conservation was greatly enhanced through this treatment.
CONTEXTUAL INFORMATION
This object is a bronze ring excavated from the site of Verulamium in 1955 with an approximate date of around the mid-first century AD. Based on the research, it is possible that the ring was originally used as a functional object to hold together straps or to create a pulley. Presently it is accessioned in St. Alban’s Museum and the Verulamium Museum, both of which are situated on the excavation sites.
PRE-TREATMENT CONDITION
The object was in a fairly robust condition. The majority of the surface was covered in an orange-brown patina. In raking light, the bronze substrate was visible under the thin layers of malachite, vivianite, iron oxide and cuprous oxide corrosion products. The heaviness of the ring and x-ray images indicated that most of the original metal still remained. There was a pit on the exterior where blue-green intergranular and purple corrosion were apparent.
REASON FOR TREATMENT
This object was received by the St. Alban’s and Verulamium Museums for treatment. The blue-green corrosion on the surface of the piece presented a potential problem which prompted the desire for conservation treatment
(Above) X-ray image of the ring at 80 kV for 90 seconds.
ANALYSIS
X-rays were done at 80 and 90 kV for 90 seconds. The x-ray images revealed that most of the original metal remains in the ring and there is no extensive intergranular corrosion present.
Portable X-ray Fluorescence (pXRF) was used to analyse the front and reverse sides of the ring for metal compositions. The machine was a Delta InnovX Premium handheld pXRF calibrated to alloys and calculating weight percentages. Acquisition time fell between 15-18 seconds.
Fe-1.37%
Cu-70.64%
Zn-1.30%
Sn-16.12%
Sb-0.14%
Pb-10.43%
Copper Alloy Ring
UCL Lab Numer: 8916
© University College London. Images may not be reproduced.
BEFORE FRONT
CONTEXTUAL INFORMATION
This object is classified as a basalt lithic flake, which was created in the process of making a hand-axe. It was excavated in Olduvai Gorge, Tanzania with an age of 1.4 million years. It is attributed to the Homo erectus species and thus represents the material culture of Acheulean tool technology, which followed and was probably contemporaneous with the Oldowan culture of the Homo habilis species. Since this flake has the potential to show the transition between the Oldowan and Acheulean technologies, it is a very important piece of material culture that provides crucial information about hand-axe technology and prehistoric humans throughout time.
PRE-TREATMENT CONDITION
The flake was in a somewhat stable state. It was broken into three larger pieces and several smaller pieces during excavation and was reconstructed by archaeologists using a combination of adhesives that included ParaloidTM B-72 20% w/v in acetone and HMG ParaloidTM B-72 , Alteco Super Glue® (cyanoacrylate) and Paleo-Bond™ PB002, PB40 and PB100 (Phenol 4,4’ 1-methylethylidine). There was an excess of adhesive and sediment that extended out of the joins and disfigured the stone surfaces on both sides. This excess adhesive and sediment was also affecting the closeness and stability of the joins.
TREATMENT OF A BASALT HAND-AXE FLAKE
AFTER FRONT
REASON FOR TREATMENT
To ensure the stability of the flake for future research, it was requested that the flake be cleaned of the old adhesive and sediment, the joins to be deconstructed and realigned and areas of loss stabilized through filling, if necessary. Any areas that were filled should be tinted so that that the appearance of the flake is accurate and informative. This flake—along with the others allocated to the MSc group—were to be returned to Olduvai Gorge in July where further research and display would occur.
DECONSTRUCTION, CLEANING AND RECONSTRUCTION
The attached pieces were deconstructed using an acetone atmosphere in a Stewart® (polyethylene) container. The accession number on the front of the stone was covered in cyclododecane (volatile sealing wax) to prevent the solubilization of the ink. Cleaning of the old adhesive was done using a no. 15 scalpel, acetone and brushes under a microscope. Four detached pieces were reconstructed with ParaloidTM B-72 50% w/v in acetone.
STABILIZATION
Stabilization of the flake occurred through the filling of the top left corner with ParaloidTM B-72 50 % w/v in acetone tinted with dry pigments (bone black, titanium white, fuller’s earth). This area was filled to increase the stability of the reconstructed pieces which had unsupported, overhanging edges. This reduced the risk of accidental breaks or detachment of the pieces in the future.
(Above) Image of the top corner of the flake after filling with ParaloidTM B-72 50% w/v in acetone tinted with dry pigments. Ultimately, this fill provided further stability to the reconstructed area.
(Top) Image of the basalt flake immediately after deconstruction in an acetone atmostphere.
(Bottom) Image of the flake during reconstruction.
CONDITION AFTER TREATMENT
Following treatment the stone surfaces and join edges were thoroughly cleaned of the old adhesive and sediment, enhancing the aesthetics of the stone. Removal of the adhesive also allowed closer, more stable joins to be achieved. The filling has provided added structural stability for the future. In all, the stone flake and all of its parts were successfully stabilised and the total condition improved as a result.
MY EVALUATION
This treatment provided me with an understanding of the importance of conservation in the preservation of contextual information. Through reconstructing the flake and stabilizing the joins, it was possible to save valuable information about Acheulean hand-axe technology that might otherwise be lost. Alongside this, this delicate treatment further cultivated my reconstruction, cleaning and in-filling proficiencies.
Basalt Handaxe Flake
UCL Lab Numer: 8931
© University College London. Images may not be reproduced.