Massive Deacidification
Since 1999 an extensive conservation measure has been running on the books of the DLA library: the books in question are subjected to the non-aqueous deacidification process in batches. In this process, the paper is impregnated with an alkaline reserve that counteracts future acid formation. Approximately 85 % of the library’s holdings can be deacidified, while 10 % of the holdings do not require deacidification. The exclusion criteria developed by the DLA show that a further 5% of the holdings are unsuitable for the selected deacidification process. The most important criterion for deacidification treatment is the condition of the paper. The DLA classifies this using a four grade scales (Fig. 1).
The data collected in the context of the volume deacidification project show that about 86 % of the volumes evaluated are suitable for deacidification treatment, while 14 % are not suitable for the chosen process. Among the materials that have already been deacidified, the majority of the materials evaluated so far (78% on average) can be categorised under Paper Condition Classes 1 and 2. These paper grades are potentially suitable for deacidification treatment and the process results in long-term deacidification and buffering of the paper.
Only about 6 % of the papers are already so severely damaged by acids (Class 3), that, while deacidification treatment is possible, it does not represent a sustainable measure as it cannot introduce a significant buffer. Approximately 10 % of the papers are categorised under Paper Condition Class 0 and do not require deacidification treatment.
Selection of the acidic papers is mainly carried out via a visual inspection, which requires a high degree of expertise and experience. In some cases, the assessment of the papers is supplemented with a spot test using the Abbey pH-Pen and visual classification of the colour change against a colour scale (Fig. 2).
The preservation of the heterogeneous original materials in the manuscript holdings of the DLA through the implementation of paper deacidification is currently being evaluated internally.
Contact
Enke Huhsmann, Restorer
Preservation of Holdings Consultant
Telephone +49 (0) 7144 / 848-160
Telefax +49 (0) 7144 / 848-191
Email enke.huhsmann@dla-marbach.de