‘Once in a Whale’: The Conservation Treatment of Historic Cetacean at the Oxford University Museum of Natural History By Bethany Palumbo

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Fig.2 - The whales suspended from the roof as seen on the left.

In January 2013, Oxford University Museum of Natural History (OUMNH) closed its doors for 14 months, allowing for the long-awaited and much-needed restoration of the original Victorian roof. The scaffolding required for this work allowed conservators to access several whale skeletons suspended from the roof space and conduct thorough conservation work for the first time.
The project was named ‘Once in a Whale’ and it encompassed several large articulated skeletons (fig 2) as well as a Humpback Whale skull and the huge lower mandible of a Sperm Whale, collected long before industrial whaling depleted the population of such large individuals from the oceans. These specimens had been on continuous display since the museum opened in 1860, and were in poor condition overall.
Detailed assessment identified varied types of deterioration. Foremost was the build-up of dust and dirt sticking to a dense layer of natural oil. This oil had secreted from the bone and oxidised, forming a dense, black coating. Acidic in its composition, this fatty residue was also ruining the visual aesthetics of the specimens. The museum environment had also caused deterioration to the specimens. The building itself, Grade 1 listed with a glass roof, means there is continuous light and UV exposure as well as great humidity and temperature fluctuations. Bone is extremely sensitive to environmental factors and this unstable environment had caused a loss of moisture and destruction of the bone matrix, resulting in bleaching, cracking and delamination.
With only 6 months in which to complete the conservation treatment, the priorities were to clean and stabilise the specimens, permitting them to withstand further decades on display.
The specimens were lowered in situ and a scaffold built securely around them. This became fondly known as the ‘whale tank’. The primary (and most time-consuming) phase of treatment was cleaning and this was completed in 3
phases (fig 3). Firstly, a vacuum cleaner was used to remove decades of fibrous dust and 70% ethanol was then wiped over the surface to remove any surface grease or engrained dirt. The final stage used aqueous ammonia which aimed to remove the oxidised oils and was applied in a method documented by conservators working at the University of Bergen (Turner-Walker, NiC Issue 26, October 2011). The ammonia, diluted to 5% in water, worked by the process of saponification, turning the fatty acids into soap scum which could then be wiped or vacuumed off the surface (fig 4). As ammonia evaporates completely, there is no risk of chemical residues being left behind. The treatment could also be done in situ and so was ideal for our project.
The second stage of treatment was to stabilise the specimens, internally and externally. Once the dense surface oils were removed, the bones were assessed for structure and strength. The bones of each specimen varied greatly, with some more friable and brittle than others. Many factors might have caused this including the age of the bones or the method of initial preparation; however there are unfortunately no records in the museum archives. Where bone surfaces were more fragile, they were consolidated using Butvar B98, a polyvinyl butyral resin in ethanol. This was injected into porous areas or painted onto the surface and was absorbed readily by capillary action. This resin was selected for its binding efficiency, flexibility and favourable results in UV, visible light and heat exposure studies. It also has a reasonably high glass-transition temperature (Tg) of 62-68 °C, meaning it would survive exposure to the environmental extremes of the museum’s roof space. While very high UV conditions may cause the cross-linking of Butvar B98, leading to an insoluble network (Horie 2010), we felt its application was justified.
Although it will not be entirely reversible in the distant future, it will ensure the survival of these specimens for decades to come and thus allow them to continue to serve their purpose in the museum displays.
With the bones reinforced, the final task was to re-articulate them. In many areas, the specimens were lacking scientific accuracy. This was caused either by insufficient knowledge of anatomy at the time of preparation or by
gradual, natural movement. For example, cartilage was still present in some areas and over the decades this had dried, contracting and pulling the bones into unnatural positions. Not only were some bones misaligned but in
some cases they were missing entirely. This was a common occurrence with teeth or rib bones. The existing wires used for articulation were composed of iron and copper and these had corroded, staining and weakening the associated bone.
For the safety of the museum visitors and the whales suspended over them, it was agreed to replace all accessible wiring. Through discussion with other preparators, we learnt that new skeletal mounts are usually articulated using a combination of epoxy resin and internal metal supports. However, conscious of the unpredictable museum environment, it was agreed that the risk of epoxies failing prematurely was too great. The installation of internal metal supports would also result in further damage to the bone material. For these reasons, the original wring method was reinstated using stainless steel and the existing drill holes where possible (fig 5).
Once completed, the specimens were transferred to new positions and installed higher than previous to take advantage of the vast roof space. The specimens now shine with a brightness not seen for many decades and have become a main exhibit in the museum.
The project blog, ‘onceinawhale.com’, was created to capture and convey the conservation process and it aimed to discuss the material science and treatment rationale when working on such unique materials. However, it received such positive publicity that the whales became stars in their own right, featuring in other creative disciplines. Artistic professionals and enthusiasts were inspired to join us in the ‘whale tank’ to illustrate, film and photograph the work being carried out. The skeletons also featured in the BBC4 television series ‘Secrets of Bones’ (2014) and the project was eventually awarded ‘Highly Commended’ in the Conservation and Restoration category at the 2014 UK Museum and Heritage Awards.
Overall the project was a great success. The whales have shared their own complexities and we have learnt a great deal regarding bone material and how variable its degradation can be depending on its direct environment. The project has also taught us how important it is to consider an objects purpose in relation to the treatment it receives. These whales serve the museum as educational, scientific specimens and the conservation treatment took this into consideration, cleaning and strengthening them to withstand further time on display. We expect them to be a focal point within the museum’s displays for many more decades to come.