Harrow and Hillingdon Geological Society

NHM Palaeo Conservation

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NHM Palaeontology conservation Unit

We had a truly wonderful conducted tour around the Palaeontology Conservation Unit of the Natual History Museum, and our thanks go to the staff who put in so much effort to make our day memorable.

The department has a huge range of work in conservation, much of which is to ensure that specimens are stored properly and will not deteriorate. Many specimens at the museum have been stored for very many years and not always in the best possible way. The PCU finds better ways of conserving the specimens for the future. This includes environmental controls, monitoring of vibrations and pest control.

We were allowed to take pictures so they can speak for themselves.

Environment testing

Adrian Doyle showed us a demonstration of environmental control testing. The box on the left is the environment and a sample of bone (see close-up below) has been mounted with a strain guage connected to it. This gives a read-out on the black box above. The silver box to the right is an air-conditioning unit that can be programmed for temperature and humidity, and is connected via tubes to the environment cabinet. With this apparatus any changes in the environment can be correlated with movements in the bone.

It is important to do these experiments so that quantitative measurements can be taken. Some specimens can tolerate fairly large changes but others are very sensitive to minor changes. When conserving specimens it is important from a cost point of view to know how critical is the environment to the specimens in question.

Environment testing close up

Close up of the sample bone with the strain guage attached.

Sorry, no larger picture!

Fossil Storage

Much of the work of the department is placing specimens in storage in such a way that they are safe from damage. This specimen has been placed on a supporting cushion to prevent uneven pressure which could cause cracks to develop.

The labels are the original ones and these too need to be conserved.

Morrocan fish
This fossil fish is from Morroco. It was bought for a large sum of money and later donated to the museum. It can be seen that the back half of the tail is in fact false, and aparantly very well done. The fossil itself is being used for research purposes and, as it cannot be spoiled by removing the front, the conserver is cutting into the matrix at the back of the fish to expose the relevant bones that way.
Morrocan trilobite
This trilobite, also from Morroco, was collected by Richard Forte, author of the Earth. This one is a perfect specimen.

This slab of stone is Archaeopteryx, yes the REAL one. It is having a big makeover at the moment. It can be seen that the slab of matrix is quite thick. The specimen, together with its wooden case, weighed 48 kilos; a bit difficult to manage. As the case was in need of repair it was decided to reduce the thickness of the slab. Everything that can possibly be done to remove vibrations has been done. The slab is mounted face down on a supportive matrix (green). This in turn is on a layer of pink foam on a supportive board. The board in on sandbags.

Lorraine is demonstrating the delicate tool used to cut small piece by small piece. The pieces already removed can be seen in the plastic box at the front. This box is already heavy.

Fortunately Lorraine had a copy of Archaeopteryx to show us so we had a view of what the real thing looks like.
Acid etching

This specimen is being prepared using acid etching. This is done using 5% acetic acid (vinegar to you and me). The specimens are put into a bath of acid for three days during which the carbonate matrix is slowly dissolved. The bones dissolve at a much slower rate.

After three days the specimen is then washed repeatedly for another nine days to remove the salts that the acid has formed. It is then dried thoroughly and any visible bone is covered with a protective layer. Then it's back to the acid bath for the next round.

A time consuming process...

A nightmare job in acid etching
This is a nighmare specimen that is being slowly acid etched. It ismade up of tightly packed shells; extemely delicate ones with long thin protuberances, that are all tangled up together. As any become detatched (bottom left corner) they are collected, but the tangle may be too difficult to seperate. Only time will tell.
Glass Cephalopod
The PCU also does conservation on things other than fossils. This beautiful Cephalopod was made in Victorian times from glass. Over time glass too corrodes so, as well as producing boxes with supporting foam for the specimens, the Conservation Unit is finding means of minimising this corrosion.
More glass Cephalopods
Some more beautiful glass Cephalopods.
Glass Radiolarian

This is a glass Radiolarian. It was constructed from drawings made when they were first studied under a microscope. Some of the drawings had small errors and so these Radiolarians have the errors too.

The glass spicules all have to be stuck onto the glass sphere one at a time with exceptional care. Not a job to do after a heavy night out...

Glass Radiolarian under repair

This Radiolarian is in the process of being repaired. The glass spicules are in the box at the front.

It can be seen that there is a glass sphere within the outer sphere. Modern glass blowers are at a loss to explain how this was done.


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