Charlotte, our Conservation Officer, tells us about her work on a crocodile skull in preparation for its installation in Dinosaurs: Monster Families.
The skull and jaw (lower mandible) were incredibly dirty and were covered in an extremely thick layer of soot and dust. I removed the loose dust with a museum vacuum and soft brush and then gave the bones a further clean with alcohol on cotton wool swabs to remove the thicker layer of dirt.
You can see from the photos that the recesses in the skull that the teeth sit in are generally wider and deeper than the actual teeth causing the teeth to be loose in the skull. Originally, the teeth would have been held in place by periodontal ligaments but this tissue was removed during its preparation as a skeletal specimen.
Our curator wanted the skull to be displayed in a “life-like” open jaw pose and that meant I would need to secure the teeth back into the skull to prevent them from falling out.
To do this I used Japanese tissue paper which is a type of tissue made from the inner bark of the paper mulberry tree. Conservators use this tissue for all sorts of repairs and fills. In this case I created twists of tissue which I inserted between the teeth and bone. This filled the “void” space and created a contact area between the teeth and bone.
I soaked the tissue with a solvent based adhesive and once the adhesive dried the teeth were firmly secured in place.
The adhesive I used is reversible and that means that I can reactivate the adhesive and easily remove the Japanese tissue if a curator wants to analyse individual teeth in the future.
Now the skull and jaw can be displayed the correct way up without the loss of any teeth.
You can see our cleaned crocodile alongside dinosaur remains, eggs and more in our new exhibition Dinosaurs: Monster Families that opens Saturday 13 February.