Fluorocarbons & Sulphur Hexafluoride: Paper deacidification

It has become important to develop mass desacidification projects to address the present problem of brittle paper that is so common to library, archive and museum collections. One technique favoured by some important Public Libraries is the Wei T'o mass deacidification technique, using a mixture of carbonated magnesium methoxide and ethoxide in alcohol, utilizing a Fluorocarbon as co-solvent. Fluorocarbons were selected, firstly because of their solvency properties, and secondly because there are non-flammable, enabling the installation directly on location, resulting in low transportation costs. Furthermore, they avoid the risk of losing definitely precious documents in the case of a fire induced by using a flammable solvent, which is the case for other proposed desacidification processes.

In 1997, Wei T'o Associates Inc. replaced CFC and HCFC formulations by an HFC-134a solution. This new formulation was found suitable for use in mass desacidification of all types and sizes of books.

The National Library of Canada has treated over 890,000 books since the start of the process. The French "Bibliothèque Nationale de France" has been using a mass deacidification facility in Sablé-sur-Sarthe.

Comparable treatment have been proposed based on HFC-227.