Thesis: Dai

Thesis: Qingrou Dai

A Technical Study of Fish Collagen-based Binder for Architectural Polychrome Painting in Jiangsu Province: History and Application

Fish collagen binder derived from yellow croaker (Larimichthys polyactis) swim bladders has served as a ground layer adhesive and gilding binder in Jiangsu architectural polychrome painting since the Song dynasty (960–1279 CE). However, its historical application remains ambiguous due to inconsistent terminology and scarce material evidence. This thesis investigates its historical use, recipes, and conservation potential through archival research, oral histories, and experimental replication.

Replicated polychrome panel of Caiyitang, Changshu, Jiangsu Province, China (Qingrou Dai, 2025).
Documentary research provides historic recipes and confirms the long-standing role of fish collagen binder, particularly in sizing, grounding, and gilding, though its use in pigment binding remains debated due to cost and workability limitations. Experimental replication compared traditional and modified preparation methods. Adhesion tape tests and color change measurements before and after accelerated weathering showed that the traditional binder retained stronger adhesion and better durability after aging, while the modified binder exhibited reduced stability. A painted wood mock-up demonstrated the binder’s strength and reversibility but limited suitability for large-area pigment application due to rapid drying.

These findings reaffirm fish collagen binder’s historical significance and potential for future conservation, while suggesting further research and refinement for broader application.
Surface adhesion of traditional and modified fish collagen binders before and after weathering (Qingrou Dai, 2025).

Color differences after weathering: traditional vs. modified fish collagen mixtures (Qingrou Dai, 2025).

Thesis: Qingrou Dai

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