The Conservation of Natural History Materials

With tongue fixed firmly in cheek it has been a long standing joke in the Booth Museum that from a conservator’s perspective the ideal Natural History Museum would be situated in deep space, shielded in some way from the ravages of meteorites and other space debris.

Here, without an atmosphere, the collections would in theory be truly protected, A from light, B from dust, C from insect attack, D fluctuations in humidity & temperature, E from wear & tear.

The Museum at the end of the universe, Natural History section. ?

Situated in deep space there would be no light which as we all know causes fading by means of ultra-violet radiation. At first shielding took the form of greenhouse paint being applied to the skylights at the Booth. Later it was realised that artificial light was also a source of harmful radiation and UV filters were applied to all lights and to the case fronts. Sadly any fading is irreversible, but at least we are able to prevent further fading.

Museum dust is worse than normal dust which according to Wikipedia is as follows:-

 Dust consists of particles in the atmosphere arise from various sources such as soil dust lifted up by wind, volcanic eruptions, and pollution. Dust in homes, offices, and other human environments contains small amounts of plant pollen, human and animal hairs, textile fibers paper fibers, minerals from outdoor soil, and many other materials which may be found in the local environment.

Dirty, dusty museum objects are less attractive aesthetically and educationally. In sufficient quantities the dust can also provide a suitable nurturing environment for the development of insect pests.  The removal of this dust is inevitably harmful to the specimens. In deep space’s vacuum there would be no atmosphere and movement of atmosphere to allow the dust to circulate and settle of objects. Museum pests would of course be unable to survive in the vacuum of deep space.

Having been deprived by the Health & Safety Executive of the beneficial effects of Arsenic, Dichlorvos, Formaldehyde & Naphthalene, we attempt to reproduce the space effect, by placing vulnerable museum objects in a vacuum preferably in a freezer, or in an anaerobic container. In the Booth the most harmful pests are invertebrates misc. carnivorous beetles, moth, mites. Recently the collection received the unwanted harmful attention of a family of mice.

All museum objects are at risk from fluctuations in humidity and temperature; the two are usually linked and can be easily monitored by readings in a thermo hygrograph which plots heat against temperature.

In storage and display the movement on a molecular level caused by expansion & contraction and the change in humidity have to be minimised. In the geology and palaeontology collections increased humidity can result in harmful chemical reactions. The Booth’s fabric consisting as it does of a large amount of absorbent wood achieves a degree of natural humidity control, not however enough.

The final category wear and tear is caused exclusively by people who of course could not survive in space, neither staff nor visitors. Any movement whether for storage, cleaning or for educational purposes has an effect on specimens and must rank as the foremost source of wear and tear and damage to museum specimens of every kind.

People in the museums however are unavoidable and so, not having the deep space option we at the Booth have to make do as best as we can. It is as well to remember that even the most benign conservation treatment will impart a degree of damage. Some objects especially those made of leather, feathers and vegetable matter are particularly vulnerable to this form of harm.

Away from space but nearly as unlikely would be a form of quarantine for any specimens that leave and are returned to the museum. Ideally items that are used for loans or outreach work should be housed completely separately, to be able to avoid the introduction of insect pests to the main collections. As a general rule these items should be regarded as separate collections and as being expendable.

In the Booth the most commonly asked health and safety issue raised is the Arsenic question. Is it harmful to museum staff? Arsenic is the main reason that Booth’s collections are still with us however it has a fearsome reputation, to an extent based on Victorian hyperbole & melodrama. It has been superseded by Borax powder and to a degree by pyrethrum based insecticides making all modern specimens completely safe, but not very safe from insect attack!  Prolonged exposure to arsenic may be harmful but occasional exposure to the small quantities encountered from museum specimens will not.

Any conservation work should only be carried out by qualified staff. Any observations suggesting work required should be passed on to them, e.g. damage or evidence of insect attack. Well meaning repair work is to be discouraged firmly but politely.

Jeremy Adams, retired Assistant Keeper at the Booth Museum

At Work With…

… Lee Ismail, Curator of Natural Sciences

This is the second blog on mammal taxidermy. This time describing the processes of preparing a mammal as a posed mount rather than as a flat skin.

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The mammal used was a rabbit acquired from a local butcher’s shop which had already been semi-prepared with the belly opened up and the stomach removed. This time, there was no intention to later include the rabbit in the museum’s accessioned collections, so the usual process of weighing and measuring it was not carried out.

The removal of the rabbit’s skin was carried out in much the same way as with the fox with some differences. These differences were required for the purpose of displaying the skin as a mount rather than a flat skin. The most obvious alteration was in the preparation of the legs. In the case of the fox, each leg was cut down the entire length and the flesh was removed along with the bones. For a mounted specimen the bones need to remain as a method of support and unsightly stitch marks from incisions need to be avoided. So, with the rabbit, the skin on the legs was peeled back to the ankle joint and the flesh was removed from the bones using the scalpel. Once completed an incision was made in the sole of the foot and the muscles and tendons were removed. A sturdy wire was then fed up through the base of the foot and along the length of the bones. This wire was bound to the bone with string, before packages of wood wool and tow (plant fibres) were tied around the bones to mimic the shape of the muscles. The process was repeated on the other three legs. The position of the leg joints was recorded on an outline diagram of the carcass once the body was removed.

The preparation of the head is also different for a mounted specimen. The head of the rabbit was skinned, the same as the fox, however the central incision only went to the base of the neck. The neck and skull were then removed by turning the animal inside out. In normal circumstances the skull would be de-fleshed, then placed back inside the skin to fill out the head. However, the rabbit skull was badly damaged in this case and was not usable.

After the rest of the body was removed, the skin was washed, and any remaining flesh still stuck to the skin removed. The lips of the rabbit were sewn up to prevent the mouth opening during the drying process when the skin shrinks.

Body stuffing can either be purchased from a taxidermy retailer as a preformed plastic body or built from scratch. In our case, a body was made in the traditional way using wood wool (finely shaved wood) jute tow (used in sack cloth) and string. It was built up with wood wool, dampened with water and pesticide. This was wrapped with string at various points to secure the wool as well as to help assess the size of the body. When the body had been constructed, to the appropriate size for the skin, it was covered in a thin layer of tow and wrapped in cotton thread. This gives a smooth surface, which prevents lumps appearing in the skin.

To compensate for the lack of a skull (and Jeremy using it as a good opportunity to demonstrate how to salvage such a situation) a head was added to the body stuffing. In normal circumstances, the skull would be packed out with wood wool and modelling putty would used to fill the eye sockets and hold a pair of glass eyes in place. In this case, the modelling putty was built directly onto the head section of the body stuffing and the skull shaped by using more putty, cotton wool and string.

The whole body stuffing was then inserted head first into the skin. The wires bound to the leg bones were pushed into the stuffing material using the diagram as a guide to the position of the joints. Once the legs were anchored into place, the body was sewn up. The legs were then bent into the desired pose and the body was mounted onto a temporary wooden board to dry.

During drying the skin tightens up and sets the position of the pose. Drying involves pinning the skin into position and brushing and blow drying the fur. Once the fur looks presentable the mammal can be left to dry at room temp for several weeks. In larger mammals the skin shrinks significantly during the drying process so tanning is used to prevent it. On smaller mammals it isn’t such a problem.

At Work With…

… Lee Ismail, Curator of Natural Sciences

This article describes the processes of taxidermy.

Young Vixen

Any keen readers of the Royal Pavilion & Brighton Museums blog will know that I previously worked on bird taxidermy as part of the Monument Fellowship programme at the Booth Museum. The programme facilitates knowledge capture between retiring curators and their successors. As the fellowship draws to a close we have decided to do a series of blogs on the most complicated aspect of taxidermy, namely, preparing mammals. This first blog will examine the steps taken in the basic preparation of a mammal skin and skeleton.

Young Vixen

We start with the animal itself. In this case, we have a young (approximately six month old) vixen. She met her untimely demise following a road collision, and was brought in by a member of the public.

The procedure started in much the same way as in preparing a bird. Measurements were recorded along with the date and location of death. The animal was then weighed, which proved to be a lot messier than with a bird, as most of the blood drained from the nose when it was hung on the scales. The body was then inspected externally and examples of any parasites, such as fleas or ticks, were collected and preserved for future reference.

The next stage was to make an incision into the skin. This initial opening can be made in a number of places depending on what end result is intended. In this case, as we were aiming for an unblemished pelt, the cut was made along the centre of the chest. This was extended to the full length of the body and up to the chin. Further incisions were made along the length of each leg.

Fox Skin

Once the incisions were made, the skin was carefully removed from the body, by using fingertips and a scalpel where neccessary to free the body from the connective tissue. The body was almost entirely removed in this way. Even the tail was removed by simply easing it out, much like a very bristly sock.

Once the body was free, we moved to concentrate on the head. Again, it was skinned in much the same way, including very carefully turning the ears inside out and removing the cartilage. To finish, the gums and the flesh just behind the nose were cut through and the fur was successfully removed from the fox.

Fox Skull

A basic autopsy was then carried out, to record anything significant about the animal’s life. Our little vixen had the following injuries: shotgun pellet holes, an air gun pellet wound and a semi-healed break in her right back leg, all within her first year of life (not to mention the car accident that killed her). All these observations were recorded as part of the specimen history.

The final stage was to prepare parts of the body for skeletal preparation. This involved the removal of the head from the body as well as the broken limb. These parts were placed into a pot and simmered for two days. The pot was not allowed to boil as this fixes the fats into the bone leaving them with a permanent stain. The flesh was then removed with a combination of forceps and a toothbrush to avoid damaging any of the smaller bones. The bones were placed into a bath of petrol for a week, in order to remove any fats still present. Finally, the bones were removed, dried and then bleached in a mixture of ammonia and hydrogen peroxide.

Fox Bones

The next blog will look at preparing a mammal skin for display as a mounted specimen.