Margaret Byrnes announced in the Conservation DistList that the National Library of Medicine had been prompted by Nicholson Baker's new book, Double Fold: Libraries and the Assault on Paper, to publish a description of its preservation practices. The full text is reproduced below from their website, http://www.nlm.nih.gov/psd/pcm/nlmprespract.html.
Since 1986, NLM has conducted a program to microfilm brittle books and serials in its collection. The purpose of the program is to create national preservation masters that will ensure access to the published medical literature for researchers and libraries well into the future. The program was never conceived as a space saving measure. To date approximately 93,000 of an estimated 233,830 brittle volumes have been filmed. Priority has been given to titles indexed in Index Medicus and the earlier Index Catalogue. For the most part, volumes are filmed only if pages break at or before two double folds. All volumes are reviewed for artifactual value before filming decisions are made. During filming, strict handling procedures are followed to minimize damage.
NLM's microfilm is produced to the highest technical standards. Stable polyester-based film is used. Volumes that contain important illustrations are filmed on color or continuous tone film to enhance fidelity to the originals. NLM borrows from other libraries volumes missing from its collection to ensure that filmed runs of serials are as complete as possible. This practice creates more complete runs of these titles than are available elsewhere in the country. Within copyright restrictions, copies of the film are made available for purchase by libraries and research-ers at reasonable cost. In the past 8 years, libraries and individuals have purchased 2,137 reels of microfilm. We estimate that the proportion has been 40% libraries, 60% individuals.
NLM microfilm is inspected to ensure that no pages are missing and that all images are highly legible. Camera negatives of the film are stored offsite in a temperature and humidity controlled vault to protect them from deterioration. Camera negatives are not used to produce copies for public use.
NLM does not routinely disbind volumes prior to filming. Only those volumes judged to be unusable are discarded. The discard rate is less than 1% of all volumes filmed. Most monograph and all serial volumes are returned to the shelf.
NLM inspects film made available by commercial sources and other libraries to make sure that it is complete and of acceptable technical quality. If the film does not meet current preservation standards, NLM combines its own holdings with material from other libraries and creates a new film version that is as complete as possible. We are also inspecting film produced by NLM prior to the establishment of the preservation microfilming program and replacing any reels that are of poor quality.
Acetate film was used by NLM and other libraries for microfilm produced before the 1980s. Although NLM's storage practices have somewhat extended the useful life of acetate reels, it is inevitable that they will decay. NLM has initiated an ongoing program of monitoring their condition and duplicating endangered reels onto polyester stock before they become too deteriorated for use.
NLM's commercial binder binds 30,000 volumes per year using specifications that minimize damage and maximize the possibility of future rebinding. We repair approximately 2,000 volumes from the general collection each year. Conservation treatment is performed both inhouse and by contract on an estimated 200 rare and special collection volumes per year.
NLM estimates that its collection currently includes 991,840 volumes on acidic paper that have not yet become brittle. We carefully monitor temperature and humidity in all collection storage areas to ensure that adverse environmental conditions do not hasten the deterioration of these volumes. NLM hopes to build additional storage space that will provide optimum conditions for print and nonprint materials in the near future.
In 1987, NLM began a campaign to convince paper manufacturers and publishers to use alkaline paper for all biomedical publications. A recent survey has shown that since 1980 the proportion of acidic paper being added to the collection has decreased from 80% to 12%. We are currently identifying publishers who still use acidic paper and intend to initiate discussions with them concerning the importance of converting to alkaline paper.
NLM has increased its efforts to preserve important audiovisual resources that are becoming deteriorated or are in formats that are becoming obsolete. We are working on developing preservation strategies for materials issued in electronic form. Recently we devised a rating system to indicate to users and other libraries whether NLM has made a commitment to keep specific electronic resources permanently available.
NLM does not disbind volumes for digitization projects.