Advanced photonic techniques for the analysis of the composite French folding fan

Folding fans are complex artifacts that include a variety of materials that have been processed and assembled to produce very small supports and decorations. Unfortunately, due to their fragility, as well as the lack of suitable non-invasive and non-destructive analytical techniques, the constituent materials and stratigraphies of historic folding fans have been rarely studied so far. This work aimed to develop and demonstrate a suitable analytical methodology for characterizing a French fan and to establish manufacturing techniques employed in its production. To this goal, advanced non-destructive and micro-destructive photonic techniques were employed to gather compositional and processing information with a non-invasive approach. This artifact provided the opportunity to evaluate the potential of different techniques: Portable Raman spectroscopy (with excitation at 785 nm) was used for identifying the pigments of the painted leaves and the gemstones; particle-induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were employed to quantify metal alloy compositions and stratigraphy of the decorations; portable laser-induced breakdown spectroscopy (LIBS) allowed the measurement of elemental depth profiles of metal decorations which were congruent with those provided by PIXE. Finally, additional stratigraphic information on metal decorations, in terms of gold distribution and state of conservation, was achieved through selective laser ablation.