Interpreting elemental signatures at palm-leaf manuscript inscriptions through historical and experimental evidence using synchrotron XRF

Abstract Palm-leaf manuscript traditions are diverse, but many employ a common writing procedure: text is incised with a stylus and subsequently made visible by rubbing dark material into the grooves. Elevated metal signals have been reported at such inscriptions, although their origin remains uncertain. Here, synchrotron X-ray fluorescence mapping was applied to the palm-leaf manuscript collection of the Centre for the Study of Manuscript Cultures CSMC (Hamburg) and to experimental mock-ups to examine possible contributions from stylus abrasion, blackening materials, and preservation treatments. Historical manuscripts showed that these contributions may coexist. Similar elemental enrichment at inscriptions and cracks suggests an important contribution from applied materials accumulating in surface discontinuities. Conversely, apparently unblackened inscriptions retained localized metal enrichment, consistent with a contribution associated with incision. Comparisons with binding holes and edges, which are also tool-produced features, further supported a multifactorial origin. The mock-ups did not show consistently detectable enrichment from stylus use alone. However, traditionally used materials produced localized effects: neem oil increased Fe signals, and burnt candlenut increased Mn signals. Elemental signatures therefore record complex material histories including tool-derived and applied material contributions.