The effects of hydration on the collagen and gelatine phases within parchment artefacts

Abstract

This review discusses the need to understand the effects of relative humidity on parchment and the current understanding of parchment structure and hydration. It also provides a critical evaluation of the body of foregoing research investigating the effects of relative humidity on parchment artefacts. The critical evaluation shows that the current scientific evidence that can be used to inform the debate with regard to relative humidity guidelines for the preservation of parchment artefacts is insufficient, especially in the light of a greater understanding of parchment based documents when considered as composite materials comprising collagen and gelatine. The differential behaviour of collagen and gelatine (and consequently the effect on the interfaces between them) in terms of response to relative humidity changes, is proposed as a key factor to be considered for future studies. This review concludes with an analysis of the next steps required in parchment research in order to provide an informed advisory framework.

Variation in the sorption properties of historic parchment evaluated by dynamic water vapour sorption

“…Also included in the plot Fig. 1a is the 25 • C isotherm sorption data of Bull [11], which was also provided in a table in the review of Gonzalez and Wess [10]. In this, the collagen data of Bull shows much higher MC levels throughout the hygroscopic range compared with the data obtained herein, except at the upper RH value of 95%.…”

“…This affects the structure of collagen by its chemical modification through hydrolysis, solvation of free radicals, hydrogen bond stability, and the rate of gelatine formation [14]; therefore moisture content and the interaction of parchment with moisture is an important aspect for the preservation and storage of the parchment documents. According to the review of Gonzalez and Wess [10], recommendations for the storage RH for parchment vary considerably and there is a lack of a solid scientific foundation underpinning these recommendations.…”

“…Parchment is a complex natural material made from processed, untanned animal (goat, sheep or calf) skin. Traditionally, production of parchment involved removing of the hair in lime water molecules [10]. However, a study comparing the sorption isotherms of collagen and gelatine showed that gelatine exhibited a lower sorption capacity [11].…”

A study of the deterioration of aged parchment marked with laboratory iron gall inks using FTIR-ATR spectroscopy and micro hot table

“…At this point, the role of water should be emphasized, as it plays an extremely significant role in the stability of the entire molecule [21][22][23][24]. A significant number of water molecules, termed structural water, reside inside the triple helix and mediate hydrogen bonds between carbonyl and amino groups from one chain and hydroxyl groups of hydroxyproline units from another, while other water molecules mediate hydrogen bonding between trimers.…”

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

“…The gelatinization resulting from the action of water is accelerated by the additional energy provided by heating 2,3 . Given that gelatinization is irreversible, the major challenge for the conservation of parchment is to identify collagen in the "pre-gelatinized" state 2,3 so that suitable treatments or conservation conditions can be selected. To that purpose, Scientific RepoRts | 6:26344 | DOI: 10.1038/srep26344…”