We recently brought the X-ray fluorescence spectrometer up from West Dean, for lessons with first-year students and research for second-year students at Camberwell, and two ICON workshops that I held at the V&A museum. In the evenings I used it on my 18th French book collection to further my research into pigments used in the marbling and edge decoration at that time. More spectroscopy than I've ever packed into a week; it was exciting when we got interesting results, and we opened up a few puzzles as well.
In my French books, where areas of color are large enough, I'm systematically going through to collect spectra from each color in the marbling, or paste paper in those few cases, as well as the colored edges, to look for patterns and also to compare to contemporary accounts of what colors were used where. Spoiler alert: in the Diderot Encyclopédie, brazilwood is prescribed for red edges, but I have found only vermillion. In this case the identification is very easy; if mercury is present, it's vermillion; if not, brazilwood, carmine, or red ochre are possible. In the spectrum below, which is Kim's English book from the photo above, a mix of red ochre or bole and vermillion is indicated, which is consistent with the strong red-brown color.
In our two quick ICON workshops, I talked briefly about the principles of XRF spectroscopy and how to interpret spectra, then we had a chance to use the spectrometer on all kinds of material, including brass furniture mounts, chrome-tanned leather, tooling on leather, green-dyed parchment, a painted Indian sitar, decoration on Japanned French furniture, foxing on paper, and pigments on a globe. XRF spectroscopy is non-destructive and our instrument is portable, which does have some disadvantages but in the case of this furniture at the V&A, had a benefit over their benchtop model, which though more precise in sampling area, can't get inside the nooks and crannies of the objects.