n.a condition in which material is discolored, darkening from a neutral white shade to shades ranging from cream to brownLathrop 1980, 330The U.S. government specifies that the drafting films it purchases must not incur an increase in opacity (yellowing) of more than 5 percent after an accelerated aging test in which the material is heated at 212 degrees F. for ten hours.Roberts and Etherington 1982, 286A process or result of a gradual change from the original appearance of a material, such as paper, due to aging or environmental changes, or both. While yellowing in paper is especially pronounced in papers produced from mechanical wood pulps, it occurs to a greater or lesser degree in virtually all types of vegetable fibers. It is frequently associated with brittleness in paper (although not necessarily), and is sometimes referred to as “color reversion.”O’Connor 1984, 162Improper lighting presents a serious threat to exhibited documents. Both paper and ink undergo photochemical changes such as yellowing, fading, and accelerated physical deterioration when subjected to light; and light damage is irreversible.Roggia 1999On 29 April 1939, Barrow noted a yellowing phenomenon when he returned the laminated samples to Scribner. “A temperature of 295° F to 300° F was used on all samples with the exception of the rag book paper which was laminated at 285° F to 290° F decided yellowing occurred on the samples containing resin [sic] sizing” (Barrow 29 April 1939). Both the old papers and these modern paper samples, which had yellowed when laminated, were made from rags, that is, from cotton or linen fiber. Thus from the beginning of Barrow’s practical knowledge of the deteriorative effects of acid hydrolysis, it appeared that the yellowing was a factor of high acid and not a question of the fiber content of the paper.Cocciolo 2016a, 134Some archivists would prefer not to assign item-level metadata to large volumes of digital assets, just as some digital asset managers would rather not steward troves of yellowing papers.Harvey and Mahard 2020, 156Wood-pulp papers of the late 19th and 20th centuries are susceptible to yellowing and brittleness because of their lignin content.Harvey and Mahard 2020, 193Maintaining stable temperature is less critical than maintaining stable humidity control. Nevertheless, keep in mind that higher temperatures speed chemical reactions such as fading and yellowing.LoC 2021cOxygen promotes the deterioration of organic materials such as paper, parchment, and organic-based media including inks and other colorants. This deterioration is often visible as yellowing, embrittlement, and color fading.
