Structural Life and Tetra-Homologous Decision-Making in Dry Lacquer Conservation: An Operational Framework for Layered Textile–Lacquer Composites

Dry lacquer objects made through textile reinforcement, bulked ground layers and successive lacquer applications are layered organic composites whose stability depends on interfaces, material states and environmental history. This conceptual and practice-oriented paper proposes structural life as a descriptive model for reading those objects as products of fabrication, curing, use, ageing, previous intervention and continuing change. Building on – rather than opposing – established principles of compatibility, minimal intervention, retreatability, documentation and preventive conservation, it develops tetra-homologous decision-making as an operational risk screen. The four dimensions are material homology (physicochemical, mechanical and hygroscopic behaviour), technical homology (alignment with layered and staged construction), modal homology (material state during and after treatment), and temporal homology (future ageing, legibility and retreatability). Each judgment is linked to an evidence category – object-specific observation or measurement, mock-up or treatment trial, published analogue, or explicit assumption – and recorded as pass, conditional, fail or unknown. A high-risk failure is not averaged against favourable dimensions; it requires redesign, further testing or non-intervention. The framework is applied to lifting and delamination, curved-shell cracks, loss compensation and previous repairs, and is then illustrated through a secondary analysis of published lacquer treatment records. This application shows how named materials and procedures become appropriate only in relation to a specific substrate, delivery mode and monitoring plan. The paper does not present new object examination, experimental ageing or computational prediction. Its contribution is a transparent decision pathway that helps conservators and conservation scientists make assumptions, evidence and future risks explicit.