An X-ray fluorescence handheld spectrometer (hh-XRF) is adapted for real-time qualitative and quantitative elemental analysis in scanning mode for applications in cultural heritage. Specifically, the Tracer-5i (Bruker) is coupled with a low-cost constructed computer-controlled x–y target stage that enables the remote control of the target’s movement under the ionizing X-ray beam. Open-source software synchronizes the spectrometer’s measuring functions and handles data acquisition and data analysis. The spectrometer’s analytical capabilities, such as sensitivity, energy resolution, beam spot size, and characteristic transition intensity as a function of the distance between the spectrometer and the target, are evaluated. The XRF scanner’s potential in real-time imaging, object classification, and quantitative analysis in cultural heritage-related applications is explored and the imaging capabilities are tested by scanning a 19th-century religious icon. The elemental maps provide information on used pigments and reveal an underlying icon. The scanner’s capability to classify metallic objects was verified by analyzing the measured raw spectra of a coin collection using Principal Components Analysis. Finally, the handheld’s capability to perform quantitative analysis in scanning mode is demonstrated in the case of precious metals, applying a pre-installed quantification routine.
Thin gold leaves were frequently used to embellish post-Byzantine religious panel paintings. Measuring their thickness using non-destructive methods is essential for understanding the technology behind their creation and developing effective preservation strategies. This study describes a method for non-invasively measuring the thickness of these gildings using large-scale imaging micro-X-ray fluorescence (µ-XRF) spectroscopy. The method relates the intensity of the Au Lα X-ray characteristic transition to the thickness of the gold layer. The method offers precise measurements of gold layer thickness in the submicrometer range on gilded surfaces, while traditional methods based on the intensity ratio of the same element prove ineffective. The method was initially validated on a mock-up sample created using traditional gilding techniques. Subsequently, the gilding was examined on two case studies of Greek religious icons. The analysis accurately measured the thickness of individual gold leaves, approximately one hundred nanometers, and identified regions with multiple overlapping layers, corresponding to structures with up to four leaves. The findings confirm that this technique offers valuable quantitative insights into the materiality and artistic techniques of these cultural heritage artifacts.