Cassy Cutulle
Objects Conservation Portfolio
The Wallace Collection Internship
September 2013-February 2014
The second year of the MSc degree in Conservation for Archaeology and Museums consisted of two five-month internships. The first of these took place at the Wallace Collection in central London in the metals conservation workshop. The placement was specifically focused on the conservation of Oriental Arms and Armor, however, I was fortunate to also be a part of a range of conservation and wider museum activities such as object marking, conference organization, instrumental analysis and innovative research. The summaries below discuss several of the projects that I participated in while an intern at The Wallace Collection. Full reports of the work undertaken is available below.
Reports #1 and #2
©The Horniman Museum, London. Reports #1 and #2 may not be reproduced.
TREATMENT OF A 19th- CENTURY TURKISH SCABBARD
BEFORE FRONT
AFTER FRONT
CONTEXTUAL INFORMATION
This scabbard is Turkish in origin and was produced by Haji Sunghar in the early 1800sAD. It was collected by one of the Marquesses of Hertford in the 19th or early 20th century. The scabbard is constructed of a wooden substrate with a velvet layer on top with metal fittings. The locket, chape and metal mounts are all silver-gilt and chased in relief with foliage motifs and a groundwork stippling pattern.
PRE-TREATMENT CONDITION
The scabbard was in fair condition. The silver-gilt areas were tarnished and there was movement of the chape along the substrate. Movement of these pieces along the velvet caused darkening, loss of fibers and matting of the velvet on both sides. The velvet was also discolored from UV/Light damage over time. There were green, waxy corrosion products in several of the metallic areas. The cordage tied around the mounts was darkened and dirty and fibers were actively falling out of the cordage, even during light handling.
REASON FOR TREATMENT
Cleaning and brightening of the metal on the scabbard were requested in preparation for catalogue photography of the Oriental Arms and Armor collection. The aim was to stabilize the scabbard while aesthetically improving its appearance.
CLEANING TREATMENT
The silver-gilt areas (locket, mounts, and chape) were cleaned using 1:1 Stoddard Solvent:acetone swabs. Some Stoddard Solvent swabs were used for particularly dense waxy accretions and ethanol swabs for more dirt-based accretions. In larger areas, a dampened cotton ball was run over the surface to pick up initial dirt, and swabs were then used to clean in the crevices created by the relief decoration. Goddard’s Silver Cloth® was utilised to reduce the tarnish on the silver-gilt areas. Testing showed that the cordage was not robust enough for cleaning since the fibres were too loose.
CONDITION AFTER TREATMENT
As a result of the treatment, the scabbard appears cleaner and the metal is brighter. The removal of the waxy corrosion products and tarnish has also stabilized the scabbard.
MY EVALUATION
This treatment provided me with an excellent introduction to the conservation of historic metal objects-both in terms of the approaches undertaken and the materials used. As a result, my understanding of conservation processes became more well-rounded as I gained an understanding of how treatments may be focused differently in varying museum contexts.
Treatment of a 19th-Century Turkish Scabbard, The Wallace Collection.
Photographs by Cassy Cutulle
© Trustees of the Wallace Collection, London. Images may not be reproduced.
DRY ICE CLEANING THE ORIENTAL HELMETS COLLECTION
(Above) Several of the helmets stored in the conservation workshop in preparation for dry ice cleaning.
CONTEXTUAL INFORMATION
The Wallace Collection houses a stunning group of Oriental helmets, which currently numbers seventy-four. The helmets were collected by the Marquesses of Hertford throughout the 18th-20th centuries. The helmets predominantly originate from Pakistan and India, among other countries.
PRE-TREATMENT CONDITION
Originally the helmets were situated on display in the Oriental Arms and Armor gallery. They contained a large amount of greasy and waxy accretions alongside dirt and dust that had accumulated over time. The helmets—including the mail—had been coated in petroleum jelly at some point in the past. For many helmets, the interaction between the ageing petroleum jelly and copper alloy rings of the mail produced a green, waxy corrosion product. Out of the seventy-four helmets, ten were considered clean and not in need of dry ice cleaning. Therefore most of the mail contained greasy accretions and waxy corrosion products to some degree and was in need of dry ice cleaning. Only the mail portion of the helmets was dry ice cleaned; the bowls of the helmets were cleaned using solvents.
REASON FOR TREATMENT
Dry ice cleaning was undertaken on the Oriental Helmets Collection as a part of the larger Oriental Arms and Armor catalogue photography project. Metalwork Conservator Seoyoung Kim and I endeavored to assess, document, clean, wax and mark the entire collection of Oriental helmets. Most importantly, our work was helping to preserve the entire helmets collection for an extended amount of time.
Conservators at The Wallace Collection had tested dry ice cleaning in the past and wanted to utilize the machinery to clean the mail in an efficient and timely manner. The Cold Jet® i3 Microclean dry ice blaster was delivered to The Wallace Collection by the CryoGenesis© team for a week.
Images of the conservation workshop displaying the dry ice machinery and equipment setup (above left) and the mounting of helmets during cleaning (above right).
CLEANING
This machinery works through shaving down a block of solid CO2 and blasting it at high-speeds through a designated nozzle at various pressures and mass flows. Dry ice cleaning in this instance was conducted at a mass flow of 0.45 kg/min. and a pressure of 0.5 bar. Heat provided through a hot air dryer on low settings was used in conjunction with the dry ice cleaning to prevent the freezing up of the mail or the condensation of the ice. In all, approximately twelve dry ice blocks were used. Throughout the cleaning process, personal protective equipment such as goggles, gloves, ear defenders, respirators and lab coats were used.
The methodology constantly evolved as we tested the dry ice cleaning process and its efficiency. When the mail was only dry ice cleaned, we noticed that the result was not sufficient—greasy accretions were still present on the mail even after cleaning for more than thirty-five minutes. To save time, we then altered the plan to include the use of Stoddard Solvent. Brushing or quickly immersing the mail in Stoddard Solvent and drying with paper towels would remove and further loosen up the greasy and waxy accretions lodged between the rings of the mail, while dry ice cleaning would provide a secondary removal of any superficial corrosion products or accretion remnants. After discussion and testing, Seoyoung and I agreed that this would be the most effectual methodology because it allowed us to work more efficiently. Aside from aiding in the cleaning of the mail, I was responsible for the photographic and written treatment documentation.
CONDITION AFTER TREATMENT
As a result of the combination of dry ice and Stoddard Solvent cleaning, the mail of the helmets appear much cleaner making the ring patterns on the mail more visible and aesthetically pleasing. Additionally, the removal of the waxy corrosion proudcts has stabilized the rings and no new corrosion has been noted. The application of Renaissance Microcrystalline Wax has further protected the metal rings from corrosion in the future.
MY EVALUATION
This experience was an informative and valuable one which advanced my professional development by allowing me to acquire knowledge of a new cleaning method emerging in the field of conservation. I have since been able to conduct research on this method which I hope to develop further in the future.
Dry Ice Cleaning the Oriental Helmets Collection, The Wallace Collection.
Photographs by Cassy Cutulle
©Trustees of the Wallace Collection, London. Images may not be reproduced.
SCANNING ELECTRON MICROSCOPY OF AN ENAMEL
(Above) Image of the enamel plaque.
RESULTS
SEM-EDS analysis was conducted in variable pressure mode with the beam set to 20keV and a working distance of approximately 10mm-11mm. Seven different areas on the plaque were analysed, and a total of twenty-three spectra obtained. INCA software was used to extract the data to a Microsoft Word document.
Several details were gleaned from this analysis: the composition of the metallic stars and figurines within the enameled area of the plaque were not bronze, but copper and therefore the corrosion products represent copper oxides and not bronze disease. A copper-gilt frame is attached to the enameled plaque with nails and the presence of mercury indicated that it was mercury gilded. It is possible that the metal areas on the enameled plaque are also mercury gilded but the only trace of this is the presence of gold on the first star analysed with a weight percent of 18.3%.
This analysis proved immensely useful and because the light-green corrosion products were not characterized as copper oxides, mechanical removal was decided as appropriate and chemical treatment for bronze disease was deemed not necessary.
REASON FOR ANALYSIS
This bronze enameled plaque was produced in Florence, Italy in the early to mid-15th century and is decorated with a scene of the annunciation. It was brought to the Metals Conservation Workshop at The Wallace Collection for analysis and treatment. Light green corrosion products had formed on the metallic stars and figurines and instrumental analysis was needed to identify the corrosion products prior to treatment to help determine the appropriate course of action.
The plaque was brought to UCL's Institute of Archaeology for Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) analysis on the Philips XL30 FEG machine, equipped with high vacuum and partial pressure capabilities, which was especially useful for objects such as this one which could not be carbon coated.
(Above) SEM image of the light-green corrosion products on the enamel plaque.
MY EVALUATION
This project allowed me to understand the value of instrumental analysis in deciding conservation treatments. In a situation such as this one, it is important that we understood what we were trying clean/remove prior to intervening on it. Since we were able to discover that the corrosion products were only copper oxides, mechanical removal was appropriate and chemical treatment not necessary.
Scanning Electon Microscopy of an Enamel, The Wallace Collection.
Photographs by Seoyoung Kim and Cassy Cutulle
© Trustees of the Wallace Collection, London and University College London. Images may not be reproduced.
CLEANING A SUIT OF MAIL
REASON FOR TREATMENT
A shirt and collar of mail that had been on display in the Oriental Arms and Armor gallery was due for a cleaning. The suit of mail is made of steel and brass rings constructed in diaper patterns. On the mail there was an accumulation of green, waxy corrosion products from the interaction between the brass links and the previous petroleum jelly coating. My primary responsibility for this project was to aid Seoyoung Kim in the removal of the accretions from the links on the mail and to coat the links with Renaissance® microcrystalline wax (Cosmolloid 80 hard and BASF A waxes) to prevent corrosion.
CLEANING
Stoddard Solvent was decided as the best solvent for cleaning the mail since it would be most effective at breaking down the grease-based accretions. Immersion and gentle brushing in a Stoddard Solvent bath was decided best in terms of our time constraints.
The suit was placed in a plastic tubs and Stoddard Solvent poured in. For the first bath, a total of 5 liters of Stoddard Solvent were poured into the tubs and the mail brushed with synthetic soft-bristle brushes. When the first baths became exhausted, the Stoddard Solvent was disposed of and a second bath was created with a total of 4 liters of Stoddard Solvent. Again the links were brushed and the suit was left to soak in this bath for twenty-four hours. After this time, the mail was taken out of the bath and allowed to air dry on paper towels in a ventilated extraction room. The mail was then hot waxed using Renaissance® microcrystalline wax applied with an impregnated cotton cloth, warmed with a hot air blower and buffed with another cotton cloth. Throughout the cleaning processes, personal protective equipment such as gloves, lab coats and heavy duty respirators were utilized.
CONDITION AFTER TREATMENT
The Stoddard Solvent bath proved successful in removing the greasy accretions on and within the mail links. The cleaning and waxing treatment has further revealed the pattern of the rings. Additionally, the removal of corrosion products and the application of wax has stablized and prevented the formation of corrosion products.
(Above) Image of the green waxy corrosion products present as a result of the interaction between the aged petroleum jelly and the copper alloy rings.
(Above) An image of me cleaning the corrosion products from the suit of mail in a Stoddard Solvent bath.
(Above) Image of the suit of mail before cleaning.
Cleaning a Suit of Mail,The Wallace Collection
Photographs by Seoyoung Kim and Cassy Cutulle
© Trustees of the Wallace Collection, London and The Portland Hospital for Women and Children. Images may not be reproduced.
ANALYSIS OF "THE EXECUTIONER" SCULPTURE
Photograph of 'The Executioner'"sculpture (above left) and the x-ray image (above right).
RESULTS
The CT-scan images revealed that “The Executioner” figurine is thickly constructed of porcelain, but ultimately hollow. The sculpture is set on top of a porcelain base which is inset into wood. There is a plaster section as well, which is most likely connected to the wooden and porcelain bases. The coloring of the porcelain material within the base indicates that it is of a different quality to that of the porcelain used to make the figurine. A denser element showing up in the X-ray images of the belt around the waist of “The Executioner” suggests the use of either metal wiring or a lead glaze.
MY EVALUATION
Through my involvement I gained an understanding of X-radiography analysis and Computed Tomography imaging, how they are conducted and what information can be gained from such methods of instrumental analysis. I also learned a great deal from Dr. Robert Hill about the mechanisms of CT-scanning. The collaboration between healthcare and museum professionals was also truly inspiring and highlighted the value of such cooperative work.
REASON FOR ANALYSIS
As a part of an auxiliary research project at The Wallace Collection, instrumental analysis was requested for a porcelain sculpture (“The Executioner”). X-ray images and CT-scans were needed to assess the interior constructions of each, non-destructively. This work was conducted for curatorial research interests.
Analysis was carried out at The Portland Hospital for Women and Children in London. The X-radiography and CT-scanning machines were hospital-grade equipment utilized in the healthcare of patients at the hospital. The general brands for the equipment are General Electric© for the X-ray machinery and Siemens© for the CT-scanner.
The X-rays and CT-scanning were conducted with the object horizontally positioned on the table, face-up. Images were then digitally enhanced and assembled by Dr. Robert Hill.
(Above left) Image of the sculpture being CT-scanned and the resulting CT-scan (above right).
X-ray and CT-Scanning of 'The Executioner' Sculpture, The Wallace Collection
© Trustees of the Wallace Collection, London and The Portland Hospital for Women and Children. Images may not be reproduced.