Analytical methodological adaptations for sampling ancient pigments in provenance research

Mineral pigment provenance is a promising direction in cultural heritage particularly in ancient polychromy research. The analysis of trace elements and Pb-isotopes can provide clues about the origin of pigment raw materials. While previous investigations already showed great potential for provenancing archeological-historical mineral pigments, sampling methods and reference data collections need to be developed further to evaluate the potential and limitations of this type of research. This work tests a new sampling method for pigment provenance research that collects sample material with easily available (suffused) cotton swabs for analysis by mass spectrometry. Three artifacts decorated with Egyptian blue and red pigments were selected for comparing sampling with cotton swabs to sampling with a scalpel. All three artifacts date to the 1st century BCE: The first is a colossal marble head from Lazio, Italy, which probably belonged to a seated cult statue of Zeus, and with extensive remains of ancient red paint. The two artifacts (a slag and a fragment of a terracotta vessel) were recovered during Petrie's excavations of an Egyptian blue production facility in Memphis, Egypt. The new results are consistent with previous studies, which provides the necessary quality control for the cotton swab sampling method. This work contributes to improving sampling methods for pigment provenance analysis as well as to a better understanding of past pigment production and trade networks.