Red decay
Red decay (also known as red decay ) is damage to leather in which the solid leather surface dissolves into dust.
In addition to nitrogen oxides and ozone , leather also adsorbs sulfur dioxide from the air , which in combination with air humidity reacts to form sulphurous acid. Acid-catalyzed hydrolysis causes discoloration and collagen breakdown . In older leathers, this can occur with tanned leathers. The damage is irreversible.
The part of the name “red” comes from a special type of damage: Some chemicals added to the tanning agents to accelerate the tanning process from the middle of the 19th century had a negative effect on the aging resistance of the leather. The resulting accelerated decay of leather results in a reddish dust. Mostly it is leather from calf, goat or sheep. The Royal Society of Arts established a standing committee to study the phenomenon in February 1900. After systematic research, the cause was discovered a few years later. The tanning process was modified in the following years.
In the case of historical book covers in libraries or furniture , the problem is that this type of damage leads to severe abrasion, which on the one hand causes soiling and on the other hand further damages the objects. In libraries with historical book holdings in this time segment, this results in costs for the maintenance of the holdings .
A certain stabilization can be achieved by means of leather fat . Due to the strong discoloration, however, this is no longer used to preserve book bindings. An alternative is the introduction of hydroxypropyl cellulose (a nonionic cellulose ether , e.g. Klucel ®), which is dissolved in alcohol. However, material dissolution and discoloration can occur. However, the discoloration is less serious because the alcohol evaporates again. Since an irreparable change is made to the leather, the use of this process must be carefully considered. In principle, however, the further decay of the leather cannot be stopped, so that currently (2020) leather care measures for book covers and archive materials are not advised.
Individual evidence
- ↑ a b Bernhard Trommer: The collagen matrix of archaeological finds compared to artificially aged leather samples from historical tanning processes . Dissertation. Techn. Univ. Bergakademie, Freiberg (Saxony) 2005, DNB 973896922 , p. 68 f . on chemical principles and the history of the discovery of the phenomenon
- ↑ marvin.iuw.h-da.de
- ↑ lederzentrum.de
- ^ Maria Kobold, Jana Moczarski: Conservation of holdings: a guide for administrations, archives and libraries . 3rd, revised and expanded edition. Darmstadt 2020, ISBN 978-3-88443-058-3 , pp. 213 f ., doi : 10.25534 / tuprints-00011407 ( tu-darmstadt.de [accessed on February 11, 2020]).
literature
- Barbara Applebaum: Guide to Environmental Protection of Collections . Sound View Press, 1991, p. 185.
- Todor Stambolov: Environmental influences on the weathering of leather . In: International leather and parchment symposium. vol May 8, 1989. Deutsches Ledermuseum / Deutsches Schuhmuseum 1989, pp. 1–5. (English German)
- Leather lexicon . Association of the German Leather Clothing Industry, Munich 1975.
- Morris Charles Lamb, Ludwig Jablonski: Leather dyeing and finishing. 1st edition. Julius Springer, Berlin 1912.
- Regulations for library bindings, decided by the Association of German Librarians on June 8, 1911. - Leipzig: Harrassowitz, 1911. - 15 S. 8 ", from: Zentralblatt für Bibliothekswesen; Jg 28, H. 7/8., S. 1f ., Pp. 8-10.
- Report of the Committee on Leather for Bookbinding . Edited for the Society of Arts and the Company of leathersellers by the Viscount Cobham and Sir Henry Trueman Wood. London, published for the Society of Arts by George Bell & Sons, 1905 (first 1901).