Factors Influencing the Stability of the Writing Interface on Palm-Leaf Manuscripts: Insights from a Technological System

The long-term preservation of ink-based palm-leaf manuscripts depends on the interface between the writing layer and processed leaf surface, yet the role of leaf-surface condition remains unclear. We compared original and historically replaced leaves from a Potala Palace manuscript, and conducted functional-substitute experiments using Yunnan palm-leaf material. Sanding altered water-triggered ink transfer, but the 60-s treatment showed less transfer than both the 30-s and 90-s treatments, indicating that maximum roughening is not necessarily favorable. Confocal measurements showed inconsistent changes in Sa but higher Sz and Sdr values after sanding, while nanoCT provided qualitative structural context for the superficial organization of the leaf. These results suggest that an appropriate surface state may favor ink contact while preserving surface continuity. Taken together, the results support a preliminary interface-based technological-system framework rather than a single-factor explanation, although direct causal links remain to be tested.