What do you do with an object, purchased as a central part of an exhibition, which is corroding on display? This was the question conservators were faced with at the Pitt Rivers Museum at the University of Oxford (where I have been completing part of my third year internship) when deciding what to do with a tattooing instrument which was exhibiting signs of deterioration while on display.
The tattooing instrument (2001.41.1) was made by a tattoo artist and donated to the Pitt Rivers Museum for its Body Arts display in 2001. Since the object’s installation, it has been displayed along with other components of modern western tattoo application such as different colors of ink in plastic bottles, tracing paper, and needles. A museum guard noticed its corrosion in the winter of 2011 and drew the attention of conservation to it.
The Body Arts display with the tattooing instrument in the upper left corner.
The tattooing instrument consists of the body of the instrument, a needle, and the power cord. There is a coiled wire around the power cord where it attaches to the instrument’s body. This coil had developed loose white needle-like corrosion crystals covering most of its surface.
The object before treatment
Detail of corrosion on tattooing instrument.
The conservators reviewed the object’s condition and decided that it would be best to try and analyze the corrosion that had separated from the tattooing instrument before deciding to remove it because of the central role it played in the display. The loose white powdery corrosion below the object was collected and brought back to the lab. Spot tests for chlorides and carbonates were conducted using the protocols in Odegaard et al. (2005). The corrosion products tested negative for carbonates and positive for chlorides.
A lead spot test was conducted using the Plumbtesmo papers, which produce a pink color in the presence of lead. However, the area around the sample turned orange. A known sample of lead turned the paper a pink color, indicating that the orange result was not due to issues with the test paper but to the sample.
The Plumbtesmo papers with the known lead on the left and the unknown sample on the right
Due to the inconclusive spot tests, the tattooing instrument was removed from display for analysis with XRF. The coil and corrosion products were examined with X-Ray Fluorescence spectroscopy (XRF) (Bruker Tracer III-V). Based on the XRF results, the coil is composed of iron coated with cadmium. The corrosion product, when analyzed on its own, had a strong cadmium peak indicating that it was the cadmium that was corroding. When the exhibition case was opened to remove the object, it smelled strongly of pesticides like dichlorobenzene or naphthalene. There is a possibility that the organic acids from the pesticides or other materials in the case reacted with the cadmium, as discussed by Scott and Derrick (2007).
Portable XRF spectrum showing the presence of cadmium.
Once the corrosion product was identified as cadmium, which is hazardous to our health, we took additional health and safety precautions by wearing particulate masks in addition to gloves and lab coats when handling the object and samples. The corrosion product was removed from the object with a scalpel and brush and kept inside a glass jar for later analysis that might be able to indicate the cause of the corrosion. After removal of the loose white corrosion, the coil had a dull fogged silver-white appearance consistent with cadmium corrosion (Scott and Derrick 2007). The surface of the coil was slightly uneven in sheen and not uniform in appearance.
The object after treatment.
Detail of the coil after treatment.
After deliberation, we decided to place the object back on display even though the exhibition environment may be contributing to its corrosion. The tattooing instrument comprises a central part of the exhibit and was made and donated for the purpose of being displayed in it. These factors were weighed against the fact that the object had taken ten years to develop the corrosion we had just removed and therefore we expect that it will take several more years for the corrosion to return. Its condition will continue to be periodically monitored for the growth of additional corrosion. Now after examination and treatment, the tattooing instrument can be viewed again within the context of various components used for Western tattooing and enjoyed by visitors to the Pitt Rivers Museum.
The tattooing instrument back on display after treatment.
Bibliography
Odegaard, Nancy, Scott Carroll and Werner S. Zimmt. Material Characterization Tests for Objects of Art and Archaeology. London: Archetype Publications Ltd, 2005.
Scott, David A. and Michele R. Derrick. “Deterioration of Cadmium-Coated Instruments in Museum Storage.” Studies in Conservation 52 (2007): 59 – 68.
Robin Ohern (’12)
All text and images on this blog are © Pitt Rivers Museum, University of Oxford. The posting is the opinion of Robin Ohern and doesn’t necessarily reflect the Pitt Rivers’ position, policies or opinions.
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