Fig. 6: MA-XRF maps, UV images, and micrographs.

a Visible light photograph of Self-Portrait with Flowered Hat (1883–1888, Mu.ZEE), courtesy of Adri Verburg, KMSKA. MA-XRF scanning area is marked in yellow. A reconstruction of the two overpainted signatures and dates has been added in white. b–d MA-XRF element maps: chromium (Cr-K), zinc (Zn-K), and cadmium (Cd-L), all present only in later additions, such as the hat flowers and corner arches. e Lead (Pb-L) map showing its presence in both the ground and paint layers. f The cobalt (Co-K) map shows how the original background was more blue than currently visible. g, h Iron (Fe-K) and mercury (Hg-L) maps corresponding to the original dark, realistic portrait. In both images, an overpainted signature was found, indicated with a yellow rectangle. This area is shown in detail in (k). i Overview of the areas where details were taken. j Detail of the UIVFP image showing a local varnish on the face, courtesy of A. Verburg, KMSKA. k MA-XRF composite map of iron (green) and mercury (red) revealing two overpainted signatures: “J. Ensor 85” (vermilion) and “Ensor 85” (red/brown pigment). l, m Details of the visible signature and date “J. Ensor 1883” under visible light and under UV light. n Micrograph showing white-pink paint covering horizontal cracks in the paint layer below, indicating the time between the original portrait and the pink additions. o Micrograph of the cheek showing a skin-colored paint layer on top of a thick, locally applied varnish.