Down to the wire!

The next exciting new chapter in our ‘Once in a Whale’ conservation project involves the re-articulation of the cetacean specimens. This includes (where appropriate) removing old, corroded wiring from between bone and cartilage joints, consolidating the bone and re-articulating the skeletons with new wire. This blog entry gives an insight into this process and our experiences gained so far.

Bottlenose Dolphin skull dearticulated into upper and lower mandible

Bottlenose Dolphin skull, with lower mandible removed

Consolidation and repairs
Once the bones are individually removed, we assess their structure and strength. The specimens appear to be extremely varied in both their texture and structural integrity. Some skeletons are more friable and brittle than others, which could be due to variety of reasons, including their age or initial method of preparation. Unfortunately, we have no record of the latter.

Where bone surfaces are more fragile, we are consolidating the bone with Butvar B98 (polyvinyl butyral (PVB) resin ) in ethanol. This consolidant was selected for its binding efficiency combined with flexibility. With a reasonably high glass-transition temperature (Tg) of 62-68 °C, as well as favourable results in UV, light and heat exposure studies, Butvar B98 was deemed suitable for use on these specimens, as it would survive exposure to the environmental extremes of the museum’s roof space. It also dries with a matt finish to look natural against the bone.

B. Palumbo injecting consolidant before covering bone with clingfilm

B. Palumbo injecting consolidant before (experimentally) covering bone with cling-film to slow solvent evaporation

While very high UV conditions may cause cross-linking of Butvar B98, leading to an insoluble network (Horie 2010, P.145-7), we felt it’s application was justified. Although we won’t be able to remove it entirely 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 as display specimens in the museum. We are applying the consolidant by injection into pores in the bone, or by painting directly onto the surface.

Fractures in the bone, are being re-adhered with Paraloid B44 (ethyl methacrylate co-polymer resin) in acetone.

Repaired bone fracture in Bottlenose Dolphin's skull

Bone fracture and wiring before and after treatment on Bottlenose Dolphin’s skull

Repaired fracture on Bottlenose Dolphin's vertebrae

Repaired fracture on Bottlenose Dolphin’s vertebrae

While Paraloid B72, a Feller Class A material, has excellent ageing properties, its Tg is only 40°C. Working with the same group of resins, we selected Paraloid B44, which due to a slight composition ratio variation, has a Tg of 60°C (Horie 2010, p.159-160) and is therefore more suited to our museum environment.

Challenges and opportunities
We thought we had a dilemma on our hands when some of the old, corroded copper wiring had become stuck, particularly in cartilage joints, causing the wire to snap during attempts to remove it with pliers. Who knew what nuggets of knowledge entomologists have when encountered over a cup of tea in the staff room? When faced with mounted insects, whose metal pins have developed verdigris, entomology staff at OUMNH run an electric current through the pin to heat it, thus slightly melting remaining fats in the insects’ body, allowing the pin to slide out of the specimen.

Heating the corroded copper wire before it can be pulled out

Heating corroded copper wire on the Bottlenose Dolphin’s pectoral fin before it can be pulled out

We tried the method first using a battery, before being presented with a soldering iron- which worked like magic- just heating the copper wire sufficiently, to slightly melt the surrounding cartilage, enabling the wire to be pulled free. It really helps to talk to colleagues about your work- you never know what ideas and gadgets they may have!

Reference issues
While the bones guide the re-articulation process to some extent (e.g. spacing of ribs), working on intuition has not always proven anatomically accurate. Sourcing reliable reference material has also been surprisingly challenging. Questions such as: how inflated should the rib cage be? At what distance from the vertebrae should the floating pelvis hang? How should phalange digits be spaced and how many bones were there originally?

Left and right phalanges on Bottlenose Whale, showing spacing between digits

Left and right phalanges on Bottlenose Whale, showing spacing between digits

To answer some of these questions, we have been in touch with a number of specialists, from Alaska to Scotland. Slowly the information we need is being assembled, allowing us to articulate our specimens as accurately as possible.

Team work
While we conservators feel to some extent protective over our own ‘adopted’ specimens, this project stage encourages us to work together. Given the size and weight of ribs, sternums and skulls etc. we rely on each other to help position, support, check for symmetry and tighten joints made.

Working as a team re-articulating the Orca Whale

Working as a team re-articulating the Orca Whale (G. Aboe, N. Crompton, B. Palumbo)

Work in progress
Ribs- The Bottlenose Dolphin’s (Tursiops truncatus, Montagu, 1821) ribcage was crying out for re-wiring and re-shaping and to ensure its preservation and improve its scientific accuracy. Following the dismantling, consolidation and re-assembly with new wires, its shape was improved and strengthened with an additional wire cross-link at its widest point, the 7th rib (Post, 2012).

Bottlenose Dolphin's ribcage and wiring before and during treatment

Bottlenose Dolphin’s ribcage and wiring before and during treatment

Skull- While rewiring the Bottlenose Dolphin skull, we took the opportunity to open the mouth slightly, partly to ensure its teeth didn’t abrade each other as well as to allow visitors to study the teeth in more detail. Doesn’t he look happy now?

Bottlenose Dolphin skull before and after rewiring and widening of mandible opening

Bottlenose Dolphin skull before and after rewiring

We are under continued pressure to complete our ‘Once in a Whale’ conservation project before the scaffolding is due to be taken down, following the completion of roof repairs. Alongside that, we also have pieces of a Humpback Whale ((Megaptera novaeangliae (Borowski, 1781)) skull to address- check out our next blog entry, to see our enormous challenge ahead!

Further readings:

  • Horie, V. 2010. Materials for Conservation. Organic consolidants, adhesives and coatings. 2nd edition. London: Butterworth-Heinemann.
  • Post, L. 2012. The Whale Building Book. A Step-by-Step Guide to Preparing and Assembling Medium-sized Whale Skeletons. Self published.

Gemma Aboe, Assistant Conservator
Reviewed by Bethany Palumbo, Conservator of Life Sciences

Objects of intrigue- a relative of Moby Dick’s?

As part of our cetacean conservation project, we have recently been treating the lower mandible of a Sperm Whale (Physeter macrocephalus Linnaeus, 1758), the largest of the toothed whales. This specimen originally  came to the Museum from Christ Church Anatomical Museum in Oxford (Malgosia Nowak-Kemp, Collections Manager). Our specimen’s jaw, measuring 4.56m in length, is thought to have originated from an ‘88 foot long’ (26.82m) Sperm Whale from the pre-industrial whaling period (pre 1840), far exceeding contemporary species sizes (Malgosia Nowak-Kemp, Collections Manager). It is rumoured to be one of the largest held in a museum collection. Do you know of any larger Sperm Whale mandibles out there? 

Sperm Whale mandible below and above scaffolding platform

Sperm Whale mandible below and above scaffolding platform

The lower mandible, consisting of dense bone and cone-shaped teeth, rests upright against an architectural column at the entrance of the museum, yet is currently surrounded by a scaffolding network and a horizontal platform in the upper third of the jaw. The areas readily accessible to human touch, were visibly stained with a dark grease, while teeth showed dusty water drip marks- all of which could be reduced through treatment.

G. Aboe degreasing surfaces with ammonia

G. Aboe degreasing surfaces with ammonia

Surface areas before (dark) and after (light) treatment

Surface areas before (dark) and after (light) treatment

As conservators working beneath this imposing structure, or at a considerable height, we are made to feel very small and the work conjures up images of Moby Dick, a mythical albino Sperm Whale, immortalized in Herman Melville’s 1851 novel Moby Dick, or the Whale.

Moby Dick book illustration, p510

Moby Dick book illustration, p510

Moby Dick upon being harpooned capsized a fictional boat, killing all but one of its men, the story of which has inspired numerous adaptations and illustrations, (four of which the illustrator in me has selected for visual indulgence).

Moby Dick illustrations (R. A. Forshall, L. Pearson, Book Covet, Kiss my Shades)

Moby Dick illustrations (R. A. Forshall, L. Pearson, Book Covet, Kiss my Shades)

Interestingly, Herman Melville’s novel is based on a true story about a Sperm Whale that attacked and sank the American whaleship ‘Essex(from Nantucket, Massachusetts) in the southern Pacific Ocean in 1820.
One of the survivors, a 14 year old cabin boy at the time, Thomas Nickerson, later wrote an account of the sinking titled ‘The Loss of the Ship “Essex” Sunk by a Whale and the Ordeal of the Crew in Open Boats’, eventually published in 1984.

The Essex being struck by a whale on November 20, 1820 (sketched by Thomas Nickerson)

The Essex being struck by a whale on November 20, 1820 (sketched by Thomas Nickerson)

Both fictional and factual accounts of encounters with unsuspecting Sperm Whales, provided us with plenty of thought, while working our way up and down the jaw.

Sperm Whale hunting
During the 18th and 19th century, whalers were drawn to Sperm Whales for their ivory-like teeth (18-24), weighing up to 1kg each, embedded in the lower jaw. The teeth were crafted into practical as well as decorative pieces, such as when decorated with inked engravings, known as scrimshaw. Herman Melville, in Moby-Dick, refers to “lively sketches of whales and whaling-scenes, graven by the fishermen themselves on Sperm Whale-teeth, or ladies’ busks wrought out of the Right Whale-bone, and other skrimshander articles” (Melville, 1851, ch57).

Whaling scene carved by Edward Burdett (Nantucket Whaling Museum)

Whaling scene carved by Edward Burdett (Nantucket Whaling Museum)

Spermaceti (from the spermaceti organ) and sperm oil (from blubber) were also much sought after by whalers, since these substances were heavily relied upon for commercial applications (including soap and leather waterproofing), with increased demand caused by the beginnings of the Industrial Revolution. Sperm Whale oils were used for public lighting (including lighthouses) and for lubricating machinery, (including cotton mills), before the discovery of mineral oil.

Sperm oil bottle and can (New Bedford Whaling Museum)

Sperm oil bottle and can (New Bedford Whaling Museum)

Ambergris, another popular product with whalers, is produced in the digestive system of the Sperm Whale, and was highly valued as a perfume ingredient.

While we can only ponder on the previous life story of our Sperm Whale, we endeavour to do our best to document its museum life from hereon.

Do visit our blog again, for an update on how we’re doing with re-articulating our cetacean specimens – an exciting new phase of the “Once in a Whale” project!

 Further readings:

Gemma Aboe, Assistant Conservator

How to ‘wire a whale’ workshop

The end is in sight for the completion of the cleaning phase of our five cetacean skeletons. Next we aim to address the wire connections originally used to articulate the individual bones, since the existing wire is negatively impacting the skeletons in a number of ways.

The wires (with iron and copper inclusions) have in places badly corroded, weakening the wire and causing the deterioration of adjoining bone. The wire has already snapped in some areas.

Copper corrosion staining on bone

Copper corrosion staining on bone

Other areas such as the transverse process of the vertebrae are currently too fragile or damaged to be re-wired, as seen on the Northern Bottlenose Whale. These areas will need consolidating and in some cases infilling prior to re-articulation.

Porous and damaged transverse processes on vertebrae

Porous and damaged transverse processes on vertebrae of Northern Bottlenose whale

Where wire has been used to connect broken bones, aided with an adhesive (now brittle and discoloured), we also aim to remove this and re-adhere the sections using suitable materials.

Old repair on vertebrae (wire and adhesive)

Old repair on vertebrae (wire and adhesive)

Re-articulating the cetacean skeletons also gives us the opportunity to question their anatomical accuracy and modify angles and poses where appropriate and possible.

Bethany Palumbo, Conservator of Life Sciences gave Assistant Conservator, Gemma Aboe and Conservation Intern, Nicola Crompton a crash course in articulation methods, focusing on drilling and wiring, in preparation for working on re-articulating the whale skeletons. This blog aims to share our workshop experience.

Tools/equipment used:

  • Dremel drill
  • Pliers
  • Wire cutters
  • Mechanical pencils
  • Dust masks
  • Galvanised steel wire (0.5mm -1.25mm Ø)
  • Practice bones

    Tools and equipment used

    Tools and equipment used

How to re-articulate skeletons: drilling bone

  • The first step is to find the natural position for two bones to be joined, e.g. rib heads will sit comfortably against their associated vertebrae.

    Finding natural position for two bones to join (Nicola Crompton on left)

    Finding natural position for two bones to join (Nicola Crompton on left)

  • Next, decide on the angle of the drill hole. It is important to drill in an area of bone which is strong enough to support the wire joint but is also relatively concealed, so the wire doesn’t negatively impact the aesthetics of the specimen.
  • Pencil an entry spot and desired exit spot on the first bone, this will help to control your drilling (pencil marks may be erased later if necessary).
  • Decide on a drill bit of a suitable size. We used 1mm-2.5mm drill bits for our practice.
  • Drill the hole with gentle force, careful to not break the surrounding bone which may be fragile.
  • Use an extended pencil lead to mark a suitable entry spot through the drilled hole on the second bone (to be joined).

How to re-articulate skeletons: wiring techniques

  • Twist two wire ends to secure fastening using pliers.

    Twisted wire end fastening

    Twisted wire end fastening on practice bone

  • Loop single wire ends to secure fastening, using small long-nosed pliers.

    Wire ends looped

    Wire ends looped on practice bones

  • If working with a broken bone, cross two wires and twist ends to secure fastening, (a useful technique where extra strength is required).

    Wires crossed and twisted on repair

    Wires crossed and twisted on repair on practice bone

  • We are looking into the possibility of using (jewellery) wire crimps to secure fastenings.

Comments and conclusions of workshop:

  • Drilling bone does not smell pleasant, drilling cartilage is worse, so be prepared.
  • Drilling bone produces a fine dust, so wearing a dust mask is recommended.
  • Although we looked at alternative options for wire, such as monofilament thread, we decided to work with galvanised (zinc) steel wire for its strength, corrosion resistance, affordability and fire resistance. The whales will eventually be articulated with Grade A galvanised steel wire.
  • Conduct your drilling and wiring of bones at a desk if possible, where you can manipulate and rotate bones and wires freely, (an easier challenge than working in situ on fragile and complicated joints). We will take apart the specimens where appropriate and work on each section individually before re-assembling the specimens.
  • Over tightening the wire fastening on the bone is easily done, leading to potential cracks and tears in the bone. Examples of this can be seen on the Minke Whale and Northern Bottlenose Whale. We will have to be careful that this does not reoccur.

    Torn original drill holes on

    Evidence of tears in bone surface from over tightening of wire

  • We practised using wire diameters ranging from 0.5mm to 2mm. These sizes will be used on the cetacean skeletons, in order to match existing drill holes. We will only re-drill holes where completely necessary.

If any of our blog readers can recommend other re-articulation techniques, particularly wiring methods, we’d love to hear from you!

In the meantime, we are in the process of completing (degreasing) work on our Sperm Whale jaw (Physeter macrocephalus, Linnaeus, 1758) – do visit our blog again for what may be a Moby Dick themed post…

Gemma Aboe, Assistant Conservator
Reviewed by Bethany Palumbo, Conservator of Life Sciences