microforms

Microforms are a family of information storage methods that reproduce documents at a reduced scale on film or other substrates. By compressing pages, large collections such as newspapers, journals, and archives can be stored compactly and preserved against deterioration. The main formats are microfilm, microfiche, aperture cards, microcards, and microdots.

Microfilm is typically a long strip of film carrying a sequence of reduced pages, most often in 16mm or 35mm widths. Microfiche are flat cards containing a grid of miniature images, allowing many pages to be viewed on a single sheet. Aperture cards mount a frame of film in a card that can be fed to specialized readers; microcards are pocket-sized cards with small images; microdots are tiny photographic representations of pages. These formats are read with dedicated viewers or reader-printers, sometimes alongside reprographic capability.

Creation and materials: Microforms are produced by photographic reduction of existing documents using film cameras or duplication units. Base materials have evolved from early cellulose nitrate or cellulose triacetate to modern polyester safety film. Archival formats aim for long-term stability under controlled storage conditions; older nitrate materials are flammable and require special handling. Reduction ratios vary but typically reproduce full pages legibly at reduced size.

Use and equipment: Libraries, archives, government agencies, and financial institutions have used microforms to preserve and transport records. Retrieval relies on microfilm readers or microfiche viewers, with indexing and pagination essential for locating materials, since full-text search is not intrinsic to the medium.

Digital transition: In recent decades, microforms have been complemented or supplanted by digital imaging and online access. Many institutions digitize microforms to improve access while preserving the originals as a preservation copy. Microforms remain in use where long-term preservation and compact storage are priorities.