Exploring

Preservation Microfilming

Standards/Guidelines

Microfilming is governed by a variety of standards, but it is important to keep in mind that most of these standards were developed for commercial microfilming applications, where the microfilm being produced only needs to be retained for a limited time. Thus, certain practices may be acceptable in the production of commercial microfilm that are not appropriate in the production of preservation microfilm.

General Microfilming Standards

Preservation microfilming of paper-based collections makes up only a small fraction of the micrographics industry, so addressing preservation filming is not a high priority for standards-making organizations. The American National Standards Institute (ANSI) issues various standards pertaining to imaging materials, including microfilm, and the Association for Information and Image Management (AIIM) also issues standards for micrographics. These standards can be useful in providing general information, but it is up to the individual institution to decide what level of quality is acceptable.

Guidelines for Preservation Microfilming

For specific guidelines for preservation microfilming geared toward libraries, archives, and other institutions that hold paper collections, the Research Libraries Group (RLG) has produced three publications that have come to be considered de facto standards. The RLG Preservation Microfilming Handbook (1992), the RLG Archives Microfilming Manual (1994), and the RLG Guidelines for Microfilming to Support Digitization (2003) should be consulted by any cultural institution planning a preservation microfilming project. Another basic resource is the Association of Research Libraries' Preservation Microfilming: A Guide for Librarians and Archivists (1996). All of these publications are referenced in Additional Resources.

These guidelines specify materials and procedures that must be used to ensure the permanence of the film that is produced:

• Film type: All preservation microfilm must be produced on a polyester base. Types of film include silver gelatin (the most stable); diazo and vesicular (less expensive, but not as stable); continuous tone microfilm (a silver gelatin film that can be very stable and is used for filming photographs and similar materials), and color microfilm (Ilfochrome color film, which likely has a lifetime of several hundred years in dark storage).
• Film format: The RLG guidelines are based on the 35mm roll film format, which provides a larger, better-quality image than microfiche or 16mm film.
• Film generations: Three generations of microfilm must be produced: the camera negative (e.g., the film used in the camera); a duplicate negative; and one or more positive service copies for researcher use and interlibrary loan.
• Film quality and processing: The RLG guidelines specify requirements for reduction ratio (the number of times the original is reduced); orientation of the image on the film; the legibility of the image (background density and resolution); processing of the exposed film; and inspection of the film and correction of mistakes (e.g., number of splices allowed).