Damage function for historic paper. Part III: Isochrones and demography of collections

Abstract

Background: In the context of evidence-based management of historic collections, a damage function combines aspects of material degradation, use, and consideration of material attributes that are important for satisfactory extraction of benefits from user interaction with heritage. In libraries and archives, it has been shown that users (readers and visitors) are mainly concerned with loss of textual information, which could lead to degradation being described as unacceptable, at which an object might become unfit for use and therefore damaged. The contribution explores the development of the damage function for historic paper based on data available in the literature. Results:We have modelled the dose-response function taking into account 121 paper degradation experiments with known T, RH of the environment, and pH of paper. The function is based on the Arrhenius equation and published water absorption isotherm functions for paper. New isoperm plots have been calculated and isochrones have been developed. These are plots linking points of equal expected 'lifetime' , i.e. time until an object is expected to reach the state of threshold fitness-for-use. We also modelled demographic curves for a well-characterised research collection of historic papers, exploring the loss of fitness for use with time. Conclusions:The new tools enable us to evaluate scenarios of management of the storage environment as well as levels of access, for different types of library and archival paper. In addition, the costs and benefits of conservation interventions can be evaluated. The limitations of the function are the context of use (dark storage and reading), exclusive focus on the properties of an average paper type, and de-prioritised effect of pollutants; however, the latter can be considered separately. This work also demonstrates that transparent and publically accountable collection management decisions can be informed, and challenged by, effective interaction with a variety of stakeholders including the lay public.

Characterisation of 19th and 20th century Chinese paper

“…Paper acidity/alkalinity is a crucial parameter regulating the mechanisms and defining the rates of degradation of cellulose [12]. Overall, the pH of the reference collection averaged at 7.6 ( Fig.…”

“…It is also an important variable in the damage function for historic paper [12,38,39]. As papers with a high lignin content cannot be dissolved in cupriethylenediamine, a number of samples (83) from the reference collection could not be measured.…”

“…These depend on environmental conditions as well as on material composition [12]. Within this study, traditional destructive analysis was carried out to explore pH, degree of polymerisation (DP), zero-span tensile strength and lignin content.…”

Moisture sorption and diffusion in historical cellulose-based materials

“…The data on water sorption can be further used in equations describing the rate of cellulose degradation through the hydrolysis reactions, which critically depends on the water content in paper, next to temperature and concentrations of acids (Strlič 2015).…”

“…Research into climate-related issues of the preservation of paper materials has so far predominantly focused on hydrolysis and oxidation of cellulose (Strlič 2015), as well as risk of microbiological activity starting above 60% RH (Sedlbauer 2002). However, there are two further important consequences of paper's capacity to gain moisture when the RH is high, or losing moisture when the surrounding air is dry.…”