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Paper has been used in Europe since the 12 th century and is still a key material, as proven by the ever-growing production of printing paper. Its affordable cost, natural origin and recyclability take part in this success. At the digitization era, the durability of paper is also of major importance. Permanent paper produced according to ISO 9706 standard should last a few centuries and be a good complement to digital storage for long-time archiving of documents. Determining its usable lifetimeis essential for such applications, yet this is conditioned by its mechanical strength. [1]Paper is a multi-scale structured material mainly made of plant fibres, such as wood or cotton, that are essentially composed of semi-crystalline cellulose. The ageing of paper induces the degradation of fibres through cellulose chemical scissions and chemical modifications that can lead to lack of interfiber bonding. [1] This work aims at understanding how chemical degradation leads to mechanical damage by investigating the link between microscopic structure and macroscopic behaviour of paper. The present study combines experimental testing with image analysing and numerical modelling.We obtained different stages of degradation by artificially ageing a permanent paper at 90° C and 50% relative humidity in air during 2 to 25 weeks. Mechanical measurements such as tensile and zero-span tensile strength were carried out according to TAPPI standards. The fracture surface was observed under scanning electron microscope and the bulk material was analysed before and after the mechanical tests by X-ray microtomography. [2] The images are used to determine characteristics of the fibrous network such as fibre length and bounding. These values feed a digital model of the paper, whose parameters are adjusted to match mechanical data.

Les bâtiments abritant d’anciennes collections de livres et de documents sur papier ont de tout temps subi des incendies dont l’impact est souvent désastreux. C’est notamment le cas des bibliothèques et des archives « victimes » de conflits armés. Une grande partie du patrimoine écrit endommagé par les bombardements de la Seconde Guerre mondiale a ainsi été abandonnée à son triste sort, au point de ne plus pouvoir être consultée ni même manipulée. Au cours des dernières décennies, des protoco...

Degradation of paper initiates at the molecular level and propagates along several length scales, from the fibre and the network levels towards the macroscopic, sheet scale. In particular, the scission of cellulose molecular chains and the consequent reduction of Degree of Polymerisation (DP) is a key phenomenon influencing the decay of the mechanical properties of the material. From a conservation perspective, this decay in mechanical properties is a critical factor for the handleability of paper artefacts. By considering naturally-aged paper samples made between 1840 and 1960, the current study focuses on experimentally establishing the relation between the mechanical properties of cellulose fibres, DP and age. In paper degradation studies it is common to perform zero-span tensile tests to obtain an estimation for the tensile strength of paper fibres. This method is based on the extrapolation of a few small-span tensile tests to attain a theoretical zero-span tensile strength, under the assumption that the fibre-fibre bonds take a negligible part of the load with respect to the fibres. Despite that this is an intelligent strategy, it is based on over-simplifying assumptions. Therefore, the authors recently proposed a novel methodology for the direct measurement of both strength and elastic properties of single cellulose fibres, based on optical profilometry and Digital Image Correlation (DIC) [1]. This method is also employed in the current contribution in order to accurately assess the mechanical properties of single cellulose fibres extracted from historical paper samples. Additionally, the viscosity-average degree of polymerisation of the historical papers is measured. To this aim, small pieces of each naturally aged sample are dissolved in cupriethylenediamine (CED) and the viscosity of the dilute solution is measured using a rheometer. This rheometric measurement results in dynamic viscosity of the solution from which the intrinsic viscosity of cellulose and consequently the viscosity average DP is evaluated. Such accurate measurements of both the mechanical and chemical properties of naturally aged paper samples shed light on the changes of these properties with age, and allow for directly identifying the contributions of the underlying micro-scale constituents. The obtained insights can be useful for kinetic studies and multi-scale numerical models for paper degradation. [1] An in-depth insight on the mechanical response of cellulose fibres by means of optical profilometry techniques.

In the last decade, applications of X-rays to the study of manuscripts significantly spread in both diversity and extent. They range from writing material analysis, mostly with X-ray fluorescence (XRF), permitting non-invasive characterization of inks and pigments used [1], to the investigation of the origin of writing supports [2]. In addition, XRF mapping has proved to be an invaluable tool for recovering erased text [3]. Finally, computed-tomography (CT) has shown potential in virtually unrolling rolls, making text readable without using-damaging mechanical methods [4]. Despite their growing use, little attention has been paid to the side effects of such analytical tools. We observed irreversible parchment colour changes during some experiments on dead-sea scrolls with synchrotron radiation sources. Furthermore, partial photo-reduction of iron under high intensity beam during X-ray absorption near edge structure spectroscopy (XANES) measurements of iron-gall ink on paper has been reported several times [5,6]. Such phenomena have mostly been overlooked so far, although there is an increasing awareness of the necessity to study them. We conducted experiments at the Deutsches Elektronen-Synchrotron (DESY) facilities to investigate X-ray induced structural alteration of paper and parchment to see whether the presence of absorption centres (ink and pigments) has an impact. In addition to better understanding degradation processes, we are aiming to define an appropriate methodology of analysis of manuscripts with a tolerable risk of damage. The first results concerning X-ray induced damage of cellulose materials have already been presented at the Synchrotron Radiation and Neutrons in Art and Archaeology (SR2A) [7]. We are focusing here on the results on parchment materials. References [1] - O. Hahn, B. Kanngiesser, and W. Malzer, Studies in Conservation 50, 23-32 (2005). [2] - I. Rabin and O. Hahn, Analytical Methods 5, 4648-4654 (2013). [3] - L. Glaser and D. Deckers, Manuscript Cultures 7, 104-112 (2015). [4] - W. B. Seales, C. S. Parker, M. Segal, E. Tov, P. Shor, and Y. Porath, Science Advances 2, e1601247 (2016). [5] - B. Kanngie��er O. Hahn, M. Wilke, B. Nekat, W. Malzer, and A. Erko, Spectrochim. Acta, Part B 59, 1511-1516 (2004). [6] - G. Banik, G. Kolbe and J. Wouters, Actes des quatri��mes journ��es internationales d�����tudes de l���ARSAG, 205���217 (2002). [7] - A. Gimat, S. Schoeder, M. Thoury, S. Paris-Lacombe, V. Rouchon, I. Rabin, L. Glaser, and A.-L. Dupont, SR2A (2018).

A total of 868 historical wooden archival boxes from the municipal and regional archives as well as from the French National Archives were studied by archaeodendrometrical techniques. The boxes were shown not to be airtight and to emit moderate concentrations of volatile organic compounds. The interactions between their content and the indoor environment were studied to investigate whether the emitted volatile organic compounds can impact the stability of the cellulosic documents and metallic artefacts they contain. Regardless of their age, results have shown that the boxes do not seem to represent a particular risk for cellulosic materials nor metallic artefacts., Les interactions entre d’anciennes boîtes en bois utilisées pour le conditionnement des archives, leur environnement et leur contenu ont été étudiées. L’objectif était de déterminer si les composés organiques volatils (COV) émis par les boîtes peuvent contribuer à diminuer la stabilité des documents cellulosiques ou des objets métalliques contenus. 288 boîtes provenant d’archives municipales et départementales ainsi que des Archives nationales de France ont été datées par dendrochronologie entre le XIVe et le XXe siècle. Ces boîtes ne sont pas étanches à l’air, les faibles concentrations en COV et leur distribution qualitative montrent que, quel que soit leur âge, elles ne semblent pas présenter de risque particulier pour les objets cellulosiques ou métalliques.

A pasteboard skinned horse made mid 19th century by Doctor Auzoux presents a sophisticated polychromy, realised with a reduced palette and a protein binder implemented in order to create depth and brilliance effects, characteristic of Auzoux models. A consolidation method was developed, supported by a stratigraphic study. It uses a porcine gelatine with a high Bloom degree G1890 (Sigma ®). Of a similar chemical nature than the paint layer binder, this adhesive proved very effective for the paper/paper gluing as well as for the consolidation of the polychromy. It could also be used on other damaged Auzoux models. This work highlights the importance of the type A and B gelatine's physical and chemical properties for conservation-restoration treatments., Un desollado de caballo en cartón piedra fabricado a mitad del siglo XIX por el Dr. Auzoux presenta una policromía sofisticada realizada con una paleta reducida y un ligante protéinico aplicado de tal modo que cree efectos de profundidad y brillo característicos de los modelos de Auzoux. Apoyado en el estudio estratigráfico, un método de fijación fue elaborado, utilizando la gelatina porcina de alto grado Bloom G1890 (Sigma ®). De la misma naturaleza química que el ligante de la capa pintada, el adhesivo elegido se mostró muy eficaz no sólo para el encolado papel/papel sino también como consolidante de la policromía. Podría utilizarse sobre otros modelos de Auzoux deteriorados. Este trabajo saca a la luz la importancia de las propiedades físico-químicas de las gelatinas de tipo A y B para los tratamientos de conservación-restauración., Un écorché de cheval en carton-pâte, fabriqué à la moitié du xix e siècle par le Dr Auzoux, présente une polychromie sophistiquée réalisée avec une palette réduite et un liant protéinique créant des effets de profondeur et de brillance caractéristiques des modèles Auzoux. Étayée par l'étude stratigraphique, une méthode de refixage a été mise au point, à partir de la gélatine porcine à haut degré Bloom G1890 (Sigma ®). Elle a permis d'opérer sans avoir recours à la mise sous poids. De même nature chimique que le liant de la couche peinte, l'adhésif choisi s'est montré très efficace pour le collage papier/papier et comme consolidant de la polychromie. Il devrait pouvoir être utilisé sur d'autres modèles Auzoux détériorés. Ce travail met en lumière l'importance des propriétés physico-chimiques des gélatines de type A et B pour les traitements de conservation-restauration.

International audience; Acidity is the main factor in the deterioration of paper, resulting in a loss of material and of the information conveyed. Current methods for the stabilization and mass treatment of paper are based on the neutralization of acids and deposition of a mineral buffer, called alkaline reserve, in the fibrous network. This treatment helps the paper fighting future acidity arising during the natural aging process. The aim of our research is to develop a stabilization methodology allowing simultaneous deacidification and fiber strengthening. This novel preservation strategy for acidic and fragile paper especially targets documents that are currently banned from public access because of their poor physical condition. In previous publications, a multifunctional solvent phase process based on various polysiloxanes with amine functionality (aminoalkylalkoxysilanes) was studied as an alternative for libraries and archives. Deacidification is ensured by the amine function and reinforcement is effected by in-situ polymerization in the paper of the polysiloxane in ambient conditions. In this work we propose the use of a di-alkoxysilane (AMDES, aminopropylmethyldiethoxysilane) and a tri-alkoxy aminosilane (APTES, aminopropyltriethoxysilane), both bearing an amine function, as well as their copolymer (polyAPTES/polyAMDES) as fibers strengthening agents in a model paper made of pure cellulose.

Paper (books, manuscripts and graphic art) has conveyed artistic expression and knowledge for several centuries. The need to preserve paper-based cultural objects housed in museums and archives is ever more urgent. In order to propose adequate preservation solutions, the physical and chemical long-term behaviour of paper was investigated. Different complementary approaches that allow for a close examination of considerations such as chemical stability and conservation of paper-based artefacts are presented. Outcomes of research conducted with the aim of better understanding the reactive phenomena that unfold during the natural and artificial ageing of paper are discussed, as well as the development of analytical methods for a precise and accurate appraisal of degradation processes and levels. The impact of the collections environment and the development of preservation strategies through novel preventive and remediation processes are uncovered., Les documents sur papier (livres, manuscrits et œuvres d’art) sont les véhicules privilégiés de l’expression artistique, et de l’acquisition et la dissémination de la connaissance. La nécessité de préserver le patrimoine sur papier, constitué à travers les siècles dans les collections muséales et archivistiques n’a jamais été aussi pressante. Afin de proposer des solutions de préservation il est important de mieux connaître le comportement physique et chimique du papier à long terme. Différentes approches complémentaires permettant un examen des problèmes majeurs afférents à la stabilité et à la conservation des documents graphiques du patrimoine culturel sont abordées. Nous évoquons les travaux menés sur la compréhension des phénomènes réactionnels se déroulant au cours du vieillissement naturel et artificiel du papier et le développement de méthodologies analytiques permettant d’apporter des informations précises et nouvelles sur les processus de dégradation et les niveaux d’endommagement. Les questions relatives à l’environnement des collections et au développement de stratégies de préservation par des procédés préventifs et curatifs nouveaux sont également présentées.