**3. Results and Discussion**

#### *3.1. Pigments*

We propose the use of certain pigments on the basis of qualitative observation of MA-XRF maps, hyperspectral distribution maps and associated characteristic reflectance curves. In the case of Prussian blue and cadmium red the extraction of representative spectra from hypserspectral maps supported the identification of pigments. The earliest known manufacturing dates for potential pigments (Table 1) were used to propose *terminus post quem* for the prints. XRF data can be used to calculate elemental concentrations and therefore quantitatively identify the presence of certain elements; however, in our case approximate identifications were sufficient to address research questions concerning the prints' provenance. Summaries of all proposed identifications are given in Appendix A and data supporting this study are available in the associated supplementary information file.

**Table 1.** Earliest known date of commercial availability for pigments used to date the prints in NU Special Collections.

