Testing Taxidermy specimens with handheld XRF

XRF


Testing for hazardous elements such as arsenic, mercury, cadmium and lead in taxidermy specimens can be easily achieved using the Tracer 5i and its advanced spectral software.

 

 

Why it is important to test collections

Knowing which specimens in a collection contain traces of toxic elements can reduce exposure and insures correct handling (gloves, dust mask and protective clothing) and storage precautions are taken. Records linking specific chemicals to particular objects or specimens are uncommon, making testing necessary. Using an instrument such as the Tracer can allow collections to create a catalogue informing which specimens contain traces of poisonous materials. Any natural history object exhibiting powdery or crystalline deposits should be tested for arsenic contamination.

Prolonged exposure to these toxins can cause serious health problems. Arsenic, for example, can be easily introduced to the body through inhalation, and absorbed through the skin or ingestion. Over time can lead to chronic toxicity, poisoning, and ulceration of the skin. Exposure to mercury compounds can similarly be easily absorbed and can cause nervous disturbances, tremor of the hands, insomnia, and loss of memory, irritability and depression.

The History of Taxidermy

Taxidermy is the art of preparing, stuffing and mounting of skins of animals with lifelike effect.

In the eighteenth century the battle to preserve and protect collections against pests, meant that further development was necessary. The eighteenth century is of particular significance as museums and galleries were becoming more common place, and there was a rise in naturalists and collectors possessing large quantities of information and material from Africa, Asia and the New World.

Early approaches of taxidermy included pickling specimens in alcohol, embalming or fixation of anatomical preparations and mounting by rough taxidermy techniques followed by drying, particularly with heat. Whilst alcohol stopped insects, the display was extremely limiting as specimens had to be kept in sealed containers.

Jean-Baptist Bécoeur (1718-1777) developed a formula for arsenical soap, which was kept secret until his death in 1777. The formula was then passed to the taxidermists of the Muséum National d’Histoire Naturelle and became the preferred method of preparation there.

Most famously, Louis Dufresne (1752-1832), a Muséum taxidermists published the process in Nouveau dictionnaire d’histoire naturelle and then in the expanded second edition of the Nouveau dictionnaire. Dufresne’s validation captivated naturalists as this was the highly regarded method of the Muséum, which had one of the largest collections of preserved birds which were known for their exceptional state of preservation. Dufresne also had a collection spanning forty years which he sold to the University of Edinburgh in 1819, which was added evidence that the arsenical soap worked.

By 1830’s arsenic, especially arsenical soap (although powders and solutions were also used) had become the standard preservative against insect attack. Historically mercuric chloride has also been used for similar purposes in taxidermy.

The lasting legacy of the use of arsenic and mercuric chloride is shown in writings of taxidermy published in the nineteenth and early twentieth centuries. The area if taxidermy shifted from a problem for collectors to a valuable technique. It also meant that an increase of writing as more specimens were available as collections became more stable and sizable.

Why was arsenic and mercuric chloride effective?

Arsenic eagerly adheres to keratins and is not easily removed, even by washing. Arsenic applied to the interior of the skin eventually migrates to the exterior most likely by mineral efflorescence. Mercuric ions bond strongly with protein, especially keratins, affording almost immediate protection for exterior of specimens.

Interestingly arsenic was used on birds at the Smithsonian collection until the early 1970s and was still recommended for mammal taxidermy as late as 1981.

The new method of case storage instead of open storage has helped to contain insect infestations. Fumigation is also used to effectively keep potential insect infestations under control. The raised awareness of health hazards from exposure to metallic poisons has greatly reduced the use of arsenic in recent years.

Resources

Hawks, CA & Williams, SL 1986, ‘Arsenic in natural history collections’. Leather Conservation News, vol. 2, no. 2, pp.1-4.

Farber, PL 1977, ‘The Development of Taxidermy and the History of Ornithology’, Isis, vol. 68, no. 4, pp. 550-566. Available from: http://www.jstor.org.ezproxy.library.uwa.edu.au/stable/230009 [19/10/2017].

Sirois, PJ 2001, ‘the analysis of museum objects for the presence of arsenic and mercury: non-destructive analysis and sample analysis’. In Collection Forum, vol. 16, no. 1-2, pp. 65-77.

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