Week 4 – 3rd to 7th October – Steneosaurus obtusidens

The Natural History Museum concentrates its conservation efforts on preventative conservation. My supervisor Gill manages the environmental monitoring of the museum. Although any conservator must prefer remedial conservation, the practice of preventative conservation is a priority because it can prevent a specimen requiring interventive treatment. I started week 4 with a crash course in environmental monitoring in the museum – with a museum of this scale the problems are endless, but it’s fair to say that all museums pose a unique set of challenges to overcome. It seems impossible to perfect the environment in the museum which is a real headache as it would be a priceless protection to the collection. Relative humidity and temperature are the most important factors measured, but there are many more. Some factors, like power and flood are specific to single rooms, but absolutely imperative to the safety of the collection in that area. The museum uses the Darca 2 Heritage database and Eltek radiotelemetry system to collate information from the departments within the London and Tring museums.

This week we decided upon my main project piece – or rather my supervisor Gill and Head of Conservation Chris settled upon an appropriate challenge for me. Steneosaurus obtusidens –  a 1.5 metre long Jurassic marine crocodile skull from the Oxford Clay in Peterborough. The specimen poses multiple conservation issues – none of which I was familiar with having never worked on fossilised material before. The specimen was mounted in polyurethane form on a wooden board – the foam was brittle and is a known carcinogenic. The specimen had a number of fills from previous conservation work – but since this time (unknown) it has cracked and fractured extensively. This would initially seem to have been caused by the failure of the mount but after investigation the specimen was suffering with pyrite oxidation. Pyrite oxidation is common in specimens from the Oxford Clay and is “fuelled” by high relative humidity – so it may appear that the specimen deteriorated as a result of the environment, but this would be investigated at another time.

Steneosaurus obtusidens

To start my project I needed a work request form from the curator and then I was able to proceed with a condition report and conservation work plan – this would take me some time as I didn’t know what work needed doing, but after imposing on my colleagues I was able to draw up a plan and get an idea on what I would be doing. The week (and weeks to come) would be taken up by the project. I sketched the specimen as well as photographing it. Many people don’t understand what drawing can offer that photography cannot supply – I believe it enables the drawer to focus on morphology, structure and line – to show what is important in the context of its use, or to show the specimen in its entirety by “fixing” the perspective to prevent the focus on one area more than another. I love to photograph but I do believe drawing is a special skill that is at risk of being lost.

Preliminary sketch of Steneosaurus obtusidens

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