New analytic equipment

31 August, 2009

XRF in use
Conservator Samantha Hamilton using the XRF equipment to analyse a bird specimen.
Source: Museum Victoria

Recently purchased equipment now allows Museum Victoria’s conservation department to detect what’s in the collection on an elemental scale.

The portable X-Ray Fluorescence Spectrometer (XRF) was funded by a grant from the Victorian Managed Insurance Authority (VMIA), a statutory authority that helps protect state assets such as the museum’s collections.

“We’ll be able to use it throughout the collection,” said conservator Elizabeth McCartney, who has been using the new XRF. “It’s extremely quick and gives us an immediate yes/no answer about which elements are present.” Previously, MV had to send objects away for analysis, which was expensive and time-consuming. Another benefit is that it is non-destructive; the process does not require samples to be removed from heritage objects, which causes minor but irreversible damage.

The new machine also complements the geology department’s X-Ray Diffraction (XRD) equipment. XRD is used to identify molecular structure, and combined with XRF can provide detailed information about the composition of all kinds of materials.

Currently the XRF is being used to analyse animal specimens that will go on display in the new exhibition Wild: amazing animals in a changing world. Many of these specimens are decades old and were preserved with historic taxidermy methods. Before the advent of climate-controlled collection stores and modern pest management techniques, natural history specimens were incredibly vulnerable to attack by an army of pests including museum beetles, clothes moths and carpet beetles. To prevent these pests literally eating precious specimens to dust, taxidermists used deterrent substances such as arsenic. “It was quite common up until the 1970s and 1980s,” according to Elizabeth, “and it’s an issue for the people who handle or work on the specimens such as the collection managers and preparators.” By identifying specimens containing these old deterrents, the museum knows which objects require precautionary handling practices such as wearing gloves and masks.

Elizabeth is excited about future applications for the XRF. “We can use it to work out which metals are in an alloy, for example, and it will be great to use it for pigment analysis.” Pigment technology changed rapidly during the 19th and 20th centuries and it can be difficult to know what was used in old dyes and colouring agents. Some pigments are notoriously susceptible to fading, such as the red dyes used in the recently-acquired sugar model of Captain Cook’s cottage, and knowing exactly what’s in them will help the conservators protect objects against degradation.

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