Pigment analysis

Scientific pigment analysis can identify the materials used by the artist or in the construction of an object, highlighting the use of both organic and inorganic pigments. The identification of certain pigments can be used to assist in dating an artwork or artefact, placing it within a certain period. Pigment analysis can be used to ascertain the authenticity of a work. This is only possible when the pigments identified indicate a specific period or previous research has documented the certain materials characteristic to the artist in question's palette.

Currently at Grimwade Conservation Services, scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDS) and x-ray fluorescence (XRF) is available for the analysis of inorganic pigments (such as lead, cadmium, titanium, zinc, tin and cobalt-based pigments). SEM/EDS requires the removal of a minute sample from the paint layer, while XRF is non-destructive, requiring no sample removal. In both methods of analysis, the sample material is irradiated with electrons resulting in the emission of x-rays characteristic to the elements present, and therefore identifying the inorganic pigments in the sample (example of SEM/EDS spectra below, with lead predominate in the sample).

Fourier transform infrared spectroscopy (FTIR) is an analytical technique that can identify organic pigments and dyes by characteristic absorption of infrared radiation.

FTIR requires sample removal, however it is non-destructive to the sample. While the technique can give a good indication of the materials present, complimentary analysis might be required to confirm results.