Non-destructive collection survey of the historical Classense Library. Part I: Paper characterisation

Natalie Brown,Dirk Lichtblau,Floriana Amicucci,Floriana Coppola,Alberto Modelli,Matija Strlič

doi:10.1186/s40494-020-00432-w

Natalie Brown, Dirk Lichtblau + Show 4 more

Open Access

https://doi.org/10.1186/s40494-020-00432-w

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Abstract

An innovative survey was conducted of the collections of the historical Biblioteca Classense, located in the urban area of Ravenna (Northern Italy). The survey aimed to evaluate the current conservation state of the book collections, where 297 paper-based items, including incunabula, manuscripts and books, dating from the 14th to the 20th century, were selected for analysis. This innovative survey was carried out non-destructively by assessing degradation visually and by measuring NIR spectral data followed by multivariate data analysis. Chemical and physical paper properties, important for paper characterisation and implementation of conservation strategies were determined, including paper type, pH, degree of polymerisation (DP), tensile strength, lignin, protein, and rosin content. This survey provided a significant quantitative dataset for rag paper covering a 600-year period. The analysis of DP changes over time allowed the first experimental estimation of the rate constant for historical rag paper, i.e., (4.2 ± 0.6)·10−7 year−1, which was validated with predictions based on the Collections Demography dose response function for historic paper taking into account the past climate in Ravenna. Statistical methods were employed to describe the correlations between the measured variables and different features of the books, suggesting that the degree of polymerisation can be used as a general proxy for rag paper mechanical strength.

Highlights

Within Italy, there is a rich papermaking history as it was one of the first great centres of European papermaking
Two large-scale studies have previously investigated the chemical and physical properties of historic rag papers [22, 24], and the present study offers additional data which allows an in-depth analysis of rag paper degradation
The present results suggest that intrafibre bonding is the principal driver for increased tensile strength of rag papers, and inter-fibre bonding is of secondary importance, which is a significant conclusion related to the use of degree of polymerisation (DP) as a general proxy for rag paper mechanical strength

Summary

Introduction

Within Italy, there is a rich papermaking history as it was one of the first great centres of European papermaking. Commercial mills were established as early as 1268 and medieval mills in Northern Italy supplied large quantities of paper to Central and Northern Europe until the 15th century [1,2,3]. Fundamental changes were introduced compared to papermaking in the near East; including the use of stamping hammers to macerate rag fibres, the inclusion of watermarks and the introduction of animal glue as a sizing agent, replacing the use of starch. In response to this, lignincontaining wood fibres were introduced into the pulp mixture from the 19th century on, and groundwood pulp became the main fibre source for commercial paper. In the 19th century, rosin gradually replaced gelatine as the main commercial sizing agent [4], following Moritz Illig’s invention of rosin-alum sizing in 1807. Sizing with rosin-alum is rare; reactive sizing agents, Brown et al Herit Sci (2020) 8:88 such as alkylketene dimer or alkyl succinic anhydride that work under neutral or alkaline conditions, became by far more common

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