Mass deacidification is a term used in Library and Information Science for one possible measure against the degradation of paper in old books (the so-called "slow fires").

One technique proposed was to place books in an evacuated chamber, then introduce diethyl zinc (DEZ). In theory, the diethyl zinc would react with acidic residues in the paper, leaving an alkaline residue that would protect the paper against further degradation. 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, and a range of other chemical reactions between DEZ and other components of the book (glues, bindings) caused further damage and the production of unpleasant smells. Regardless, in the 1980s, a pilot plant for mass deacidification using this process was constructed by NASA, but it was discovered in 1986 that the DEZ had not been removed in one of the deacidification runs and was pooled in the bottom of the chamber, and probably remained within some of the plumbing. DEZ is violently flammable in contact with oxygen, 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.

The chemical company AKZO made later attempts at refining the process; though the risks of fire and explosions were reduced by better process design, damage and odours remained a problem. In the end, AKZO decided the process was not a viable commercial proposition, and shut down their research at the end of 1994.

External links

• An LOC paper on mass deacidification