Editing Mass deacidification (section)

== History of research and process development ==
Mass deacidification—along with [[Microform|microfilm]] and [[lamination]]—was developed during the early and mid-20th century as a response to the chemical process of [[hydrolysis]] by which the fibers that constitute paper, providing its structure and strength, have their bonds broken, resulting in paper that becomes increasingly brittle over time. [[Environmental pollutants]] can react with paper to form acids that promote oxidation, creating more acid as a by-product, which results in a positive feedback loop of autocatalytic destruction.<ref>Library of Congress. (1994). ''An evaluation of the BookKeeper mass deacidification process: Technical Evaluation Team Report for the Preservation Directorate'', Library of Congress, Appendix E.</ref> Supported in part by grants from the Council on Library Resources, William J. Barrow conducted research into paper decay and found that no more than three percent of books published between 1900 and 1949 would survive more than fifty years. In response to this, a Standing Committee on the Preservation of Research Library Materials was formed by the Association of Research Libraries (ARL) in 1960.<ref>Marcum, D. & Friedlander, D. (2003). [http://www.dlib.org/dlib/may03/friedlander/05friedlander.html Keepers of the Crumbling Culture: What Digital Preservation Can Learn from Library History] {{Webarchive|url=https://web.archive.org/web/20080514190831/http://www.dlib.org/dlib/may03/friedlander/05friedlander.html |date=2008-05-14 }}. URL accessed April 28, 2008.</ref>

Barrow also invented an aqueous process to neutralize acid in paper while depositing an alkaline buffer that would slow the rate of decay.<ref name="Ritzenthaler1">Ritzenthaler, M. (1993). ''Preserving Archives and Manuscripts''</ref> In addition to Barrow's original method, both non-aqueous—employing organic solvents—and vaporous—the Library of Congress' DEZ (diethyl zinc) treatment—methods of achieving the same results have been researched in an attempt to reduce time, labor, and cost requirements.<ref name="ifla1">Pillete, R. (2003). [http://www.ifla.org/IV/ifla69/papers/030e-Pilette.pdf Mass Deacidification: A Preservation Option for Libraries] {{Webarchive|url=https://web.archive.org/web/20080516071808/http://www.ifla.org/IV/ifla69/papers/030e-Pilette.pdf |date=2008-05-16 }} ''World Library and Information Congress: 69th IFLA General Conference and Council''. URL accessed April 28, 2008.</ref>

One technique proposed is to place books in an evacuated chamber, then introduce [[diethylzinc]] (DEZ). In theory, the diethylzinc would react with acidic residues in the paper, leaving an alkaline residue that would protect the paper against further degradation.<ref>Porck, H. (1996). Mass deacidification. An update of possibilities and limitations. [http://www.knaw.nl/ecpa/PUBL/porck5.htm DEZ] {{Webarchive|url=https://web.archive.org/web/20080311000502/http://www.knaw.nl/ecpa/PUBL/porck5.htm |date=2008-03-11}}. URL accessed December 2, 2007.</ref> In practice, the heating required to remove trace water from the books before reaction (DEZ reacts violently with water) caused an accelerated degradation of the paper, a series of chemical reactions between DEZ and other components of the book (glues, bindings), caused further damage, and produced unpleasant aromas. In the 1980s, a pilot plant for mass deacidification, using this process, was constructed by [[NASA]] and was tested on books provided by the Library of Congress.<ref>Harris, K. & Shahani, C. (1994) Library of Congress. Preservation.
[https://www.loc.gov/preserv/deacid/proceva1.html Mass deacidification: An initiative to refine the diethyl zinc process] {{Webarchive|url=https://web.archive.org/web/20100811073926/http://www.loc.gov/preserv/deacid/proceva1.html |date=2010-08-11 }} URL accessed December 1, 2007.</ref> In 1986 it was discovered that the DEZ had not been removed in one of the deacidification runs and pooled in the bottom of the chamber, possibly remaining within the plumbing. DEZ is violently flammable when it comes in contact with either oxygen or water vapor, so the vacuum chamber could not be opened to remove the books within. Eventually, explosives were used to rupture the suspect plumbing; suspicions of the presence of residual DEZ were confirmed by the subsequent fire that destroyed the plant. In his book ''[[Double Fold]]'', [[Nicholson Baker]] discusses the failure of the NASA program at great length.

The chemical company [[AkzoNobel]] made later attempts at refining the process. The risks of fire and explosions were reduced by a better process design, however, damage and odors remained a problem. In the end, AkzoNobel determined the process was not a viable commercial proposition and shut down their research at the end of 1994.