Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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calcium hydroxide

A strong alkali (Ca(OH) 2 ), which can be formed by the reaction of calcium oxide (CaO) with water. If the oxide is treated with only sufficient water to make it crumble to a fine, white, dry powder, slaked lime is produced. By slaking the paste formed from the oxide with an excess of water, a suspension called "milk of lime" is formed. A clear solution of the hydroxide in water is known as lime water. Calcium hydroxide is used extensively in a very strong solution (pH of approximately 11.4) in the LIMING and UNHAIRING of hides and skins in leather manufacture, and in the deacidification of paper. In the latter use, the resulting pH is approximately 11.0, and paper so treated is easily oxidized unless the pH is reduced by exposure to carbon dioxide or the paper is treated subsequently with a solution of calcium bicarbonate. (31 , 363 )

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