Towards a diagnostic protocol for the study of modelling pastes in monumental terracruda sculpture

• Diagnostic protocol for studying modelling pastes of monumental terracruda sculpture is proposed. • Circular workflow integrates archaeological, analytical, textual, ethnographic data. • Organic compounds in modelling pastes reveal clay-processing technological strategies. • Findings support a “clay alchemy” enhancing raw earth for durable sculptural modelling. • Step forward for conservation diagnostics and understanding technological variability. This paper presents an emerging diagnostic protocol for the study of modelling pastes in monumental terracruda sculpture, a distinctive technological tradition of monumental sculpture in air-dried clay. The study combines some newly acquired analytical data from Uzbek case studies with previously published results, integrating them with textual and ethnographic evidence to establish a diagnostic framework for material characterization and conservation decision-making. The proposed approach builds on a circular process of comparison and feedback between different sources of knowledge (archaeometric analyses, historical textual evidence, and traditional practices) each informing and refining the others. This interdisciplinary synthesis allows the identification of functional and compositional variations within historical examples and provides the basis for interpreting regional and chronological patterns in the production of terracruda sculpture. By formalizing this integrative workflow, the paper aims to define a reproducible methodological framework for future studies and conservation strategies concerning monumental terracruda sculptures preserved in archaeological and historical contexts, as well as dispersed fragments held in museum collections worldwide.