| Abstract: | CONCLUSION. For a national library with a commitment to comprehensive conservation, paper deacidification is an appropriate method to maintain usability of its collections in the original format. Mass deacidification of paper is an integral part of conservation, starting with stable library bindings and finishing with appropriate storage. The mass deacidification of paper constitutes a major added value for the SNL in both its conservation and library functions. The deacidification strategy focuses on prevention, as well as optimising the use of financial resources in the time available. Priority is given to collections that do not require extensive preselection. 98 % of modern stocks in the general collection can be de-acidified with "the papersave swiss"-process. Some 95 % of the 275,000 documents deacidified to date, have come through de-acidification without change. Changes are observed in an average of 5 % of the items treated; the majority of these are slight and moderate bleeding from the binding or printing inks or other surface changes in the binding area. Deposits or mechanical damage of the bindings have not been observed. Holdings with a percentage of changes in excess of 5 % (category A and B) are not deacidified at present. This is an incentive to optimisation of the selected procedure. To monitor the quality, the concept of Risk Key Figures has been introduced. Together with the percentage values, the Risk Key Figures enable a comprehensive quality control. There are several unanswered questions that need further investigation. The on-going "leather in paper deacidification" project will determine the selection criteria for half leather bindings. Investigations about the optimum concentration of deacidification solution will minimize the risk of alkali damage of oxidized cellulose as well as treatment costs. Alternative deacidification procedures have not been considered to date. Any action or non-action will be opened for discussion. To the present state of knowledge, the benefits of the "the papersave swiss"-process outweigh the disadvantages by far. So the SNL has decided to act and not to wait.
SUMMARIES. Since April 2000, the holdings of the Swiss National Library (SNL) have been deaddified by the "papersave swiss"-process, a liquid phase process following the Battelle method. Stock published between 1850 and 1985 is being treated. 40 tons of material are deaddified per year, the equivalent of about 2000 documents per week. The documents are packed shelf by shelf for treatment and return five weeks later to the stacks. The deaddified materials are identified in Helveticat, the online catalogue of the SNL. Resources in terms of staff are required in order to handle the amount of material and control the quality of treatment. Changes in the treated materials, such as bleeding of red colours, are documented. The extent of change is evaluated numerically and the total magnitude of risk is expressed in terms of "Risk Key Figures". The "papersave swiss"-process proves to be suitable for more than 90 % of the holdings dating from the 20th century that are in need of de-acidification, while 1 to 3 % cannot be deacidified by the "papersave swiss"-process. Acceptable levels of changes were found with 1 to 5 % of the treated documents. At the moment, emphasis is put on the optimisation of the process. Research is being carried out looking into the effect of deaddification on leather and determining optimal concentration of deaddification solution. |
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