ブックタイトルConservation and Restoration of Western Paper

概要

Conservation and Restoration of Western Paper

strength. Chemical pulping achieved theremoval of lignin by using caustic soda inthe process, followed by the sulfite processwhich developed in the late 19th century. 6 InEurope, surface sizing was widely used sincethe 13th century to stop the printing inkfrom bleeding. Paper was coated with animalglue at the final stage of papermaking.But the 19th century saw the start ofinternal sizing using rosin and aluminumsulfate. Sizing was thus incorporated into thepapermaking process becoming increasinglyindustrialized. 13. Deterioration of Acidic PaperIn the several hundred years in the historyof papermaking and printmaking, the use ofwood pulp and sulfite pulp evolved rapidly.The wide use of aluminum sulfate in papersizing particularly led to the disseminationof acidic paper in the 20th century. As aresult, cellulose in the paper turns acidic andgradually degrades the paper over time. Thisled to major problems in paper items such asbooks and documents.Paper is fibers bonding together givingit suppleness and strength. Paper is madeof cellulose consisting of a polymer chainof more than 2000 glucose units 6 . Duringthe sheet formation, aluminum sulfateis added to the pulp to fix the rosin sizeto the cellulose. The sulfate ions releasedfrom aluminum sulfate, in turn, generateshydrogen ions in an aqueous condition.These hydrogen ions cause hydrolysis whichbreak the bonds in the cellulose chain(Figure 1). And therefore, in an acidic paper,cellulose chains start to break slowly, leadingto the weakening of the paper. 7 Aged paperis also known to generate organic acidscaused by the carboxyl group such as formicacid, acetic acid, lactic acid, succinic acid,glycolic acid, and oxalic acid. This is believedto accelerate the break down of cellulose. 84. Japanese Paper and Acidic PaperIn the beginning of the 7th century, thecraft of papermaking was introduced toJapan from the Korean Peninsula markingthe beginning of Japanese paper. Its rawmaterials were fibers from hemp, kozo, andgampi. 9 On the other hand, western paperdeveloped in Europe would first be producedin Japan in the early Meiji period. Themanufacture of paper using sulfate pulp andground wood pulp is to come later in around1889. Handmade Japanese paper reached itshighest production around 1897. Aroundthis time, the production of machine madeJapanese paper also progressed. 5 However,Figure 1 Hydrolysis of cellulose by hydrogen ions22