Academic thesis

Annine Wöllner:	To what extent does the grinding degree / degree of polymerization affect the stability and aging resistance of leafcasted historical papers? - empiricism and first systematic experiments	back
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Abstract:	Leafcasting is a restoration method to fill in losses as well as to strength the sheet structure of historical papers. The method is used because of its similarity to the pumping process in paper making, both in graphic, as well as in archive and library restoration. The homogeneity of results through the use of consubstantial materials convinces not only aesthetically, but also materially. It leads to more satisfying results than other complementary methods in paper conservation. The diversity in methods and materials is great. This raises the question of how one can influence the results of a restoration in terms of ageing resistance and stability. The type of fiber used becomes important and can be influenced by the selection of material and how it is processed. The processing is primarily determined by the degree of fiber grinding. It seems likely that a mixture of high and low capillary fibers – those with a high and those with a low degree - forms a strong and resistant sheet structure. The combination of a high surface-bonding and single fiber bonding trough the mixture of two different processed fibertypes should combine the good properties of both capillarities. Therefore, the question of the bachelor thesis is: To what extent does the grinding degree / degree of polymerization affect the stability and aging resistance of leafcasted historical papers? In the procedure of this thesis the literature research was followed by an experimental test series establishing a first empiricism. The preparation of the four pulps took place in a classic smock mill- three different degrees of grinding and a mixture were produced. Subsequently the test-objects were filled in with these four pulps using a leafcasting-box. The objects used in the test were all rag papers. Artificial aging was conducted on half of the test objects. The number of doublefolds, tensile strength , elongation and tear resistance had been determined for all the papers under the same conditions. Through the experimental results the strengths of the individual fibers could be comparatively evaluated. By these values it was possible to determine the so-called “endurance-factors”. On the basis of these factors each individual fiber was finally fit into an “endurance-class”, which describes the aging resistance of papers. The analysis of these experiments shows that the mixed pulp performed better compared to the pure pulps, both in the evaluations of the mechanical tests as well as defined in “endurance-classes”. Thus, the mixture of high and low capillary fibers shows greater strength and resistance to aging than those of pure pulp. The outcome of the first empirical tests can serve as a good basis for further scientific research. Because the quality of leafcasting is determined not only by the pulp and processing alone. Also, the initial degree of polymerization of the fiber used, the sizing and other additives during manufacture such as alkaline reserves can significantly affect the aging resistance and strength. The extent of the impact of these factors, however, must be proven in further studies. The inclusion of such research and experimental results would be important to gain an overall picture of the strength and aging resistance factors influencing the choice of material for leafcasting. Top
Details:	academic institution: HAWK Hochschule für angewandte Wissenschaft und Kunst Hildesheim/Holzminden/Göttingen kind of theses: Bachelorarbeit main Tutor: Prof.Dr. Henrik Schulz assistant Tutor: Dipl.-Ing. Gangolf Ulbricht date: 2014 pages: 67
DOI (Digital Object Identifier)	https://dx.doi.org/

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