{{Short description|Phenomenon with acid in paper pulp}} {{Globalize|article|Poland|date=July 2023}} '''Acidic paper''' is paper which was manufactured using acidic substances.<ref>{{Cite book|last=Sutermeister|first=Edwin|title=Chemistry of Pulp and Papermaking|publisher=John Wiley & sons|year=1929|edition=2|location=London, Chapman & hall|language=english}}</ref> 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.<ref>{{Cite journal|last1=Zou|first1=X|last2=Uesaka|first2=T|last3=Gurnagul|first3=N|year=1996|title=Prediction of paper permanence by accelerated aging. I. Kinetic analysis of the aging Process|journal=Cellulose|volume=3|pages=243–267|doi=10.1007/BF02228805|s2cid=136945352}}</ref> This process has been called ''slow fire''.
== Causes of paper degradation == thumb|A book printed in 1920 on acidic paper, having visibly disintegrated In the mid-nineteenth century, a method of paper production became popular in which resin-alum glue was added to the paper pulp,<ref>{{Cite book|last=Barański|first=Andrzej|title=Problem kwaśnego papieru. Koncepcje badawcze, uwarunkowania i działania praktyczne|year=2001|location=Cracow|chapter=Kwaśny papier}}</ref> and the aluminum sulphate remaining in the paper, in reaction with water, forms acids. The long chains of plant cellulose, the structural material of paper, naturally decompose upon exposure to air, but this process is greatly accelerated by acids, which catalyze the decomposition (acidic hydrolysis). As the cellulose chains are cut apart, this reduces the tear resistance of the paper, and at the same time increases their cross-linking, making the paper stiff and brittle.<ref name=":0">{{Cite book|last=Wasilewska|first=J.|url=http://www.bu.kul.pl/chora-ksiazka-starzenie-sie-papierow,art_10735.html|title=Chora książka. Starzenie się papierów|year=2004|language=polish}}</ref> Parallel to the degradation under the influence of water, the cellulose chains react with oxygen, also cutting the chains.<ref>{{Cite journal|author=J. Łojewska, A. Lubańska, T. Łojewski, P. Miśkowiec, L.M. Proniewicz|date=2005|title=Kinetic Approach to Degradation of Paper. In Situ FTIR Transmission Studies on Hydrolysis and Oxidation|url=https://www.researchgate.net/publication/26413662|journal=E-Preservation Science|volume=2|page=1-11}}</ref> The lignin in the paper is also oxidized, which yellows the paper.
The gradual and eventually complete deterioration of the paper as the cellulose chains disintegrate is known as ''slow fire''. Paper acidification may be accelerated by environmental factors, especially nitrogen and sulfur oxides in polluted air.<ref>{{Cite book|last1=Havermans|first1=J|url=http://www.science4heritage.org/papylum/Papylum%20Book%20WEB.pdf|title=Air pollution and its prevention|last2=Steemers|first2=T|last3=Strlič|first3=M|last4=Kolar|first4=J|publisher=National and University Library|year=2005|location=Ljubljana|pages=153|language=english|chapter=Ageing and stabilisation of paper}}</ref>
== Consequences for archiving == thumb|left|Document showing brown stain damage after long-term storage in an acidic cardboard box The process of self-degradation of paper causes fundamental difficulties in safeguarding the collections of archives and libraries. For example, an analysis of the book collections of the Jagiellonian Library, Adam Mickiewicz University in Poznań, Książnica Cieszyńska, the AGH University of Science and Technology and the Cracow University of Technology showed that as much as 90% of the documents published up to 1996 are in the process of acidic degradation.<ref>{{Cite journal|last1=Sobucki|first1=W|last2=Drewniewska-Idziak|first2=B|date=2003|title=Survey of the Preservation Status of the 19th and 20th Century Collections at the National Library in Warsaw|url=https://doi.org/10.1515/REST.2003.189|journal=Restaurator|volume=24|issue=3|pages=189–201|doi=10.1515/REST.2003.189|s2cid=95347605|via=De Gruyter|url-access=subscription}}</ref> This means that these institutions, established to care for the documented heritage of the past, are failing this mission.<ref>{{Cite book|last=Nichols|first=S|url=https://www.clir.org/pubs/reports/pub103/contents/|title=The Evidence in Hand: Report of the Task Force on the Artifact in Library Collections|publisher=Council on Library and Information Resources|year=2001|location=Washington, DC|pages=20|language=english}}</ref>
Although the degradation of paper cannot be undone, only slowed, mass deacidification offers hope for conservation. Unfortunately, due to the difficulty of applying this technique and the rapid pace of paper degradation, it is not possible to save all the documents from the 19th and 20th centuries, and it seems necessary to select the most valuable among the endangered documents. Digitization and microfilming are other methods of rescue. Meanwhile, careful sharing and storage practices can prolong the paper's life, such as the use of acid-free storage materials and limiting exposure to light, especially in the UV range.<ref>{{citation|author=B. Zyska|title=Ochrona księgozbioru przed zniszczeniem v.2 Czynniki niszczące materiały w zbiorach bibliotecznych|date=1993}}</ref> {{-}}
== Paper de-acidification in Poland == A large-scale de-acidification project was carried out in Poland, the Acidic Paper Multiannual Government Program<ref name="bn.org.pl">{{Cite web|url=http://www.bn.org.pl/inne/wpr/kwasny.html|title = WPR Kwaśny papier}}</ref> of 2000–2008. In 1998, it was proposed jointly by librarians from Jagiellonian Library and chemists from the Faculty of Chemistry of Jagiellonian University, "to save the heritage of Polish culture in the library and archives of the 19th and 20th centuries".<ref>{{Cite book |last1=Barański |first1=Andrzej |url=https://issuu.com/archi725/docs/arch_xcix |title=Memoriał o potrzebie ratowania dziedzictwa kultury polskiej w zbiorach bibliotecznych i archiwalnych XIX i XX wieku |last2=Grochowski |first2=J. |last3=Manikowski |first3=A. |last4=Nałęcz |first4=D. |last5=Zamorski |first5=K. |publisher=Archeion |year=1998 |pages=21–35 |language=polish |access-date=2021-11-25 |url-status=dead}}{{dead link|fix-attempted=yes|date=January 2026}}</ref>
The American Bookkeeper technology was chosen, using a deacidifying agent of fine crystalline magnesium oxide suspended in an organic liquid perfluoroheptane, neutral to inks, paints and dyes. The technology allows for recycling of the perfluoroheptane. Books are immersed in a de-acidifying bath, allowing the magnesium oxide to penetrate. The bath is vertical for typical-sized books and horizontal for large or heavy items such as magazines or archives.<ref name="bn.org.pl" /> The Paper Clinic of the Jagiellonian Library in Krakow opened in 2005,<ref>{{Cite web|url=http://www.bj.uj.edu.pl/klinika-papieru/papier|title=Papier - Biblioteka Jagiellońska - Uniwersytet Jagielloński|access-date=2021-11-25|archive-date=2017-10-29|archive-url=https://web.archive.org/web/20171029150134/http://www.bj.uj.edu.pl/klinika-papieru/papier|url-status=dead}}</ref> and can de-acidify 35 tons of library materials annually.<ref name="bn.org.pl" /> A second facility has been operating at the National Library since 2007, with a capacity of 50 tons.<ref name="bn.org.pl" /><ref>{{Cite journal|last=Potrzebnicka|first=Ewa|date=2014|title=The Deacidification of Library Materials at the National Library of Poland|url=https://polishlibraries.bn.org.pl/upload/pdf/94598_Ewa_Potrzebnicka_The_Deacidification_of_Library_Materials_at_the_National_Library_of_Poland_214-224.pdf|journal=Polish Libraries|volume=2|pages=214–224}}</ref>
== Acid-free paper == {{Main|Acid-free paper}} In recent years, most books have been printed on acid-free paper, meeting ISO standard 9706.<ref>{{Cite web|url=http://papiery.archiwalne.eu/Norma-ISO-9706.html|title=ISO 9706 | Norma ISO 9706|website=papiery.archiwalne.eu |archive-url=https://web.archive.org/web/20160305104041/http://papiery.archiwalne.eu/Norma-ISO-9706.html |archive-date=5 March 2016 }}</ref> The use of long-life paper has many benefits, especially for valuable cultural documents.
== References == {{reflist}}
== External links == * [https://web.archive.org/web/20151104122754/http://www.bj.uj.edu.pl/klinika-papieru Klinika Papieru Biblioteki Jagiellońskiej] * [http://www.bn.org.pl/inne/wpr/kwasny.html Wieloletni Program Rządowy „Kwaśny papier"]
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Category:Printing and writing paper Category:Paper products