General Considerations
This introductory chapter deals with the materials and techniques used through the centuries for creating works of art and artefacts. The implementation of new natural or synthetic substances is concisely discussed, and the development of technical innova
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General Considerations Evangelia A. Varella
1.1 On Materials and Artefacts Abstract This introductory chapter deals with the materials and techniques used through the centuries for creating works of art and artefacts. The implementation of new natural or synthetic substances is concisely discussed, and the development of technical innovations elucidated. The gradual establishment of novel materials, as well as their multifaceted and complex applications in arts and crafts, is systematically though briefly exposed, in order to smooth identification studies, and permit chronological benchmarking of objects and monuments. The analysis encompasses constitutive core elements of objects, materials used for surface artistic interventions and all types of binding media.
1.2 Constitutive Core Elements of Objects 1.2.1 Fibrous Materials Fibrous materials have been utilised for creating indispensable artefacts and elaborate works of art since the dawn of civilisation. While wood is used as such, and leather is maintaining its distinct appearance even as parchment, textiles and paper are the result of sophisticated techniques respectively based on spinning and weaving yarns into fabrics or forming a pulp. Fibres—natural or synthetic—are typically organic,asbestos, the silicate mineral, being the sole notable exception. Whereas plant
E. A. Varella (&) Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece e-mail: [email protected]
E. A. Varella (ed.), Conservation Science for the Cultural Heritage, Lecture Notes in Chemistry 79, DOI: 10.1007/978-3-642-30985-4_1, Ó Springer-Verlag Berlin Heidelberg 2013
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fibres are composed of cellulose, those of animal origin are built of proteins, ranging from wool keratin and silk sericin and fibroin to leather collagen, elastin and keratins.
1.2.1.1 Plant Fibres They are mostly derived from the industrial crops cotton, flax and hemp. The cellulose content reaches 80–90 % in cotton and flax, compared to 70 % for hemp. Protein, pectin and wax traces are removed by scouring and bleaching. The monomer unit is in all cases the disaccharide cellobiose, and the degree of polymerisation varies from 5,000 units for cotton to 18,000 for flax. Consequently, the crystalline structure, achieved by means of hydrogen bonds, is highest in flax, hence the fibre is extremely durable with a high tensile strength. Known in archaic Mediterranean as an Oriental or occasionally African product, cotton has been for centuries largely imported from India, to be cultivated in Europe only from late antiquity on. The main plant yarn of pre Babylonian Mesopotamia and Pharaonic Egypt, flax, was later used up to the northern regions along with hemp, actually known to Black Sea Scythes since remote times. In both cases, the sprouts undergo lengthy hydrolytic decay to gain the threads, which are dried and vehemently separated from wooden remnants. Paper is produced by extracting plant cellulose fibres, allowing them to swell in water, and collecting the suspen
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