Raman spectroscopy can identify pigments (e.g. the mineral from which the pigment is derived) and with the proven micro spot Raman microscope SENTERRA II, the colorants of single fibers (Marco Leona article). Raman spectroscopy also allows the imaging of an area by “scanning” the area using a XY stage of the microscope.
In many cases, changes in the pigment structure (e.g. by oxidation) lead to complete color changes such as from red to brown in the aging of mercury based pigments. This is problematic when previous restorations were done by over-painting the area with an ochre based brown pigment instead of using the original red.
Often, it is not possible to transfer the object into a laboratory for analysis, or the dimensions do not allow using a microscope. The BRAVO is the state-of-the-art handheld Raman analyzer with benchtop performance including the patented fluorescence mitigation SSETM enabling the analysis objects in the field.
Natural History collections face other issues which can be readily addressed with HH XRF. In the past, the many chemicals used for the conservation of animal hides and taxidermy contained hazardous elements such as Pb, As, Hg and Cd. These could be released into the air or transferred to visitors who touch the objects. This also affects the health of the custodial and conservation personnel. With HH XRF, the object to be checked can be measured in situ. The HH XRF is placed in contact with a tripod and using the attached PC, the analyst can immediately identify the possible hazardous elements. Also, heirlooms such as bison head which was found in Oklahoma can be readily tested and one can rest assured.
Handheld XRF testing of a mounted red fox
Handheld XRF testing of Tasmanian devil hide