Spectroscopic Investigations for the Dating of Paper from the Nineteenth Century

The knowledge of the detailed material composition of paper can help art historians, archivist, librarians, paper historians, and conservators to determine the possible age of a document or a work of art. The dating of paper by the identification of specific paper components is especially applicable to paper from the 19th century. In this era, many changes in the paper production technology occurred and new raw materials were introduced in relatively short time intervals. ATR-IR and Raman spectroscopic measurements were used to analyze the chemical composition and structure of papers from the 19th century. The infrared spectra showed the general material composition of the papers. More specific information on the different paper components and their distribution in the paper were obtained by Raman microscopic measurements. The resulting Raman images visualize the detailed chemical structure of the papers including all components such as paper fibers, filler pigments, sizing agents, and color pigments. Special emphasis was made on the spectroscopic identification of different paper fiber types, like straw, esparto, and sulphite and sulfate chemical wood pulp, which were introduced to paper production during the second half of the 19th century. It could be shown that the specific spectral differences in the Raman spectra of the different paper fiber types are related to different amounts of hemicellulose xylan compounds on or in the cellulose fibers.