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Acid-free paper is paper that, if infused in water, yields a neutral or basic pH (7 or slightly greater). It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin- and sulfur-free. [1] Acid-free paper addresses the problem of preserving documents and preserving artwork for long ...
Acidic paper is paper which was manufactured using acidic substances. [1] Widely used since the mid-nineteenth century, its pages become yellow within years, extremely brittle over decades, and eventually unreadable in the library and archive collections intended to preserve them. [ 2 ]
Stop bath is an acidic solution used for processing black-and-white photographic films, plates, and paper. It is used to neutralize the alkaline developer, thus halting development. [1] Stop bath is commonly a 2% dilution of acetic acid in water, though a 2.5% solution of potassium or sodium metabisulfite works just as well. [1]
Although acid-free paper has become more common, a large body of acidic paper still exists in books made after the 1850s; this is because of its cheaper and simpler production methods. Acidic paper, especially when exposed to light, air pollution, or high relative humidity, yellows and becomes brittle over time. [1]
Paper chemicals designate a group of chemicals that are used for paper manufacturing, or modify the properties of paper. These chemicals can be used to alter the paper in many ways, including changing its color and brightness , or by increasing its strength and resistance to water. [ 1 ]
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Litmus paper after being used. The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple. [2]
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