Accelerated Ageing of Parchment: Investigation of a Photo Catalysed, Low-Heat Approach

Abstract

<jats:title>Abstract</jats:title> <jats:p>Accelerated ageing is an often-used tool in conservation research, yet difficult to apply to parchment due to the materials inherent heat sensitivity. The complexity of this organic material makes the analysis of its deterioration especially challenging. An attempt to develop a non-heat ageing protocol for parchment is described in this paper. The work was performed within the scope of a MA-thesis at the State Academy of Art and Design Stuttgart. Samples of a modern new limed goat parchment and pieces of reconstituted parchment made from bovine hide powder were subjected to a combination of light ageing and dynamic ageing at moderate temperatures. All samples were analysed with the goal to observe degradation on as many structural levels as possible: colour measurement via VIS spectrometry and light-microscopic observation of fibre damage were employed to assess visible changes. Shrinkage temperature (Ts) was measured as an indicator for the amount of intact intrafibrillar bonds and the determination of the maximum moisture absorption capacity gave an impression on the parchments overall level of hygroscopy. In addition, PMF (Peptid Mass Fingerprinting) via MALDI/MS TOF was performed on extracts from unaged and light aged goat parchment. The results of the different types of analysis showed significant degradation on different structural levels of the parchment, indicating that accelerated ageing of parchment that uses a combination of light and dynamic ageing may be a viable alternative to the more commonly applied thermal ageing.</jats:p>

Studies on the effects of mixed light-thermal ageing on parchment by vibrational spectroscopy and micro hot table method

“…On the other hand, PUV2 (corium side) showed a decrease in brightness even after short exposure time. An overall slight decrease in brightness for parchment exposed to light (low-heat approach) ageing which was more pronounced on the grain side was also reported by Kern et al [58]. The different values obtained for ΔE and ΔL between PUV1 and PUV2 could be related to the different responses to light-ageing of the protein constituting the grain and the corium sides of the parchment.…”

Spectral Features Differentiate Aging-Induced Changes in Parchment—A Combined Approach of UV/VIS, µ-ATR/FTIR and µ-Raman Spectroscopy with Multivariate Data Analysis

“…A decreasing trend in brightness is observed on the flesh side of all samples with progressing exposure time and even more prominently on the hair side of P5 H1 and P6 H2 ( Figure S4a ). This differential response to light-induced aging has been reported in the literature and is likely associated with additional, chemically less stable proteinaceous components, namely reticulin and elastin, which are more concentrated on the hair side of parchment [ 29 , 32 , 33 ]. However, this trend is not observed in all samples exposed with the hair side, as an inverse correlation between exposure time and brightness is observed for P1 H2 -P4 H2 .…”

“…These changes are more pronounced on the hair side compared to the flesh side of the samples (see Figure S2 for details). Light-aged samples show increasing ΔE* values as the exposure time progresses [ 29 , 32 ], ranging from slightly perceptible (1 ≤ ΔE* ≤ 2) to easily noticeable (2 ≤ ΔE* ≤ 10) on the hair side. Exceptions to this trend are samples P4 H2 , P5 H1 and P6 H2 , where observable changes occur only after more advanced aging.…”

“…This divergent behavior could probably be attributed to the use of chalk powder for surface treatment during production, leading to a different response to light aging. Since these parchment folios were produced over a period of ten years, this effect could also be explained by the light-induced degradation of chromophores formed during this natural and uncontrolled aging period [ 32 ]. Treatment with 80%RH results in a distinct reduction in brightness on the surface.…”

Secondary ion mass spectrometry, a powerful tool for revealing ink formulations and animal skins in medieval manuscripts

“…As far as parchments are concerned, various analytical techniques have long been used to assess their level of conservation in museum and library collections [18]. Artificial ageing [19] experiments on modern parchments have also been conducted in order to predict parchment degradation due to various environmental factors and help optimize conservation conditions as well as restoration treatments. More recently, techniques have been introduced in order to identify animal species in parchments [20][21][22].…”