René Larsen

Degradation of collagen in parchment under the influence of heat-induced oxidation: Preliminary study of changes at macroscopic, microscopic, and molecular levels

This paper examines the impact of heat-induced oxidation for new and historical parchment with the purpose of improving diagnostic tools for use in practical parchment conservation. Oxidation was generated by heat aging at 120°C in a dry oven for 24, 48, and 96 hours, respectively. The degradation was assessed on all samples at macrolevel by measuring color changes, at microlevel by measuring the shrinkage temperature as well as by performing a visual assessment of the fibers’ morphology and determining the amount of damaged fibers, and finally, at molecular level where amino acid analysis was used to reveal changes in the oxidized collagen. The study shows that the heat-induced oxidation leads to significant color changes, decrease in hydrothermal stability, as well as changes in the amino acid composition. Surprisingly, the results show that the historical parchment is more sensitive towards dry heat oxidation on a molecular level than is the new parchment. Furthermore, for the first time, we can show that physical damage reflected in the morphological characteristics of fibers can be attributed to oxidation by dry heat.

Laser cleaning of an eighteenth‐century parchment document

Abstract Laser cleaning of a late eighteenth‐century parchment document has been carried out. A Q‐switched Nd:YAG laser emitting laser radiation at a wavelength of 1.06 μm in pulses of 10 ns duration was used to remove soiling from the surface of the document; results were compared with those obtained using more traditional methods: abrasive cleaning and wet cleaning. Thermochemical analysis (shrinkage temperature measurements) and chemical analysis (amino acid analysis) have been carried out on laser‐cleaned areas to assess any detrimental changes to the structure of the parchment resulting from exposure to laser radiation. The interaction of laser radiation with three ink types on the document is also discussed. The results of this work suggest that laser cleaning at 1064 nm offers an extremely sensitive alternative to traditional methods of cleaning parchment documents in a relatively stable condition.

Assessing the condition of the Domesday Books from the visual to the molecular

This article presents a collaborative study to determine the condition within volumes of the Great and Little Domesday Book, held in The National Archives, UK. Advances in technology in both biochemical and biophysical analysis have allowed for the first time undetectable sub milligram sampling of the five-volume Great and Little Domesday Books at nine sites in total. Visual analysis was followed by microscopic fibre assessment, hydrothermal stability (shrinkage activity), amino acid analysis and microfocus X-ray diffraction. Based on the visual examination of 887 leaves in all five volumes of the Domesday Book, 587 leaves or 66% of the leaves exhibit a degree of surface gelatinisation due in part to humidification and pressing practices carried out as part of the many re-binding campaigns carried out over the centuries. Microfibre assessment indicated the percentage of damaged fibres detected varies from 56 to 100% in the samples taken, a correlation between the sum of oxidative sensitive amino acids and the observed damage of fibres was obtained. More than 1000 X-ray diffraction patterns collected showed a significant variation in amount of visible fibrillar collagen within each sample scan. Micro analysis performed here on corium collagen, means the results represent an average of the cross section of the structure of which the surface constitutes the smallest part. As the major part of damage is on the surface of the parchment leaves, the condition is likely to be worse than that reflected by the analytical results shown here. This evidence therefore prompted a re-think of the preservation protocols required to extend the usable life of the Domesday Book volumes. To this end, the preservation environment for the volumes is maintained at 40–45% relative humidity (RH) significantly lower than the recommended parameter of 55% RH.

Evaluation of Laser Cleaning of Parchment Documents with a Q-Switched Nd:YAG Laser at 1064, 532 and 266 nm

Laser cleaning experiments with a short-pulsed Q-switched Nd:YAG laser at 1064, 532 and 266 nm were performed on new clean parchment and on artificially dirtied samples. Samples were analysed with optical microscopy, low vacuum scanning electron microscopy, shrinkage temperature measurements and colour measurements. Results show that at 266 nm, laser cleaning seems inappropriate. Laser cleaning at 532 nm showed promising results at around 0.5 J/cm2 close to the cleaning threshold. Laser cleaning at 1064 nm resulted in a yellowish discoloration and at higher fluence levels surface damage.