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The Uptake of Calcium Carbonate in Paper: Immersion and Float Washing Compared for Selected Paper Samples

Acid-catalysed hydrolysis of cellulose is the most dominant process of paper degradation. A possible conservation treatment is an aqueous deacidification to remove and neutralize present acids and to introduce an alkaline reserve. Previous studies about the effectivity of alkaline treatments focussed on immersion washing. This research examines float washing as an alternative for papers that are too sensitive to be immersed and compares both techniques. Historic and modern papers were washed in aqueous solutions of calcium hydrogen carbonate. The efficiency of both treatments was compared in terms of achieved pH-values, deposit of an alkaline reserve, and distribution and morphology of the deposited calcium carbonate. The proposed treatment can be applied in small conservation studios and the results are therefore applicable in practice. The results show that float washing is a possible alternative to an immersion bath. Impurities in the paper, the condition of the cellulose-fibre, and treatment parameters have a strong influence on the formation of the alkaline deposit.