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.
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.
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.
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.
- Dremel drill
- Wire cutters
- Mechanical pencils
- Dust masks
- Galvanised steel wire (0.5mm -1.25mm Ø)
- Practice bones
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.
- 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.
- Loop single wire ends to secure fastening, using small long-nosed pliers.
- If working with a broken bone, cross two wires and twist ends to secure fastening, (a useful technique where extra strength is required).
- 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.
- 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