Degradation Characteristics of Blocked Paper Artifacts: The Chinese <i>Great Storage of Scriptures</i> from the Ming and Qing Dynasties

Blocked paper artifacts are historical papers that have become tightly bonded (sometimes partially mineralized) through combined chemical, physical, and biological degradation, making them a frequent problem in archaeological and archival holdings. To support conservation decision-making, this study aims to characterize the properties of degraded and blocked papers, and subsequently propose a mechanism for the blocking process. The Chinese Great Storage of Scriptures, dating to the Ming and Qing dynasties, is a significant Chinese Buddhist canon. A systematic approach, including microscopic observation (OM, SEM), phase composition (XRD, FTIR), and DNA sequencing of ITS amplicons, was used to analyze morphology, ageing characteristics, adhesive composition, and microbial influence on blocked paper-based objects. The results show that the blocked paper exhibits reduced cellulose crystallinity and severe acidification. The adhesive between the layers consists of inorganic deposits (quartz, muscovite, annite) and organic residues (lipid-based material, proteins). Fungal colonization contributes to the adhesion through the accumulation of hyphae and metabolic secretions within the fiber network. The dominant fungal species identified include Aspergillus sp., Cladorrhinum sp. and Acremonium sp., with Cladorrhinum sp. and Acremonium sp. being reported for the first time in ancient blocked papers. Overall, blocked scriptures result from the combined effects of inorganic, organic, and microbial agents, which form dense interlayer composites. These findings inform the development of integrated conservation strategies by addressing the specific synergies between inorganic, organic, and microbial components in blocked paper artifacts.