How to identify the microforms you have

Use the carrier-first test

Microfilm is roll-form film with images in sequence. An open reel has flanges around wound film; a loose roll is wound film without a reel; a cartridge houses film on a single hub; and a cassette encloses film on two cores. These names matter because loading and access are not the same for every carrier.

Microfiche is a flat transparent sheet with a readable heading area and a two-dimensional image grid. Jacket fiche is a transparent plastic carrier with channels holding cut strips of roll film. An aperture card is a card with one or more apertures holding microfilm; a common form carries a 35 mm frame and appears frequently in engineering, map, chart, and X-ray collections.

Put dimensions in context

The Library of Congress identifies 16 mm and 35 mm as common microfilm widths. Those measurements describe the film itself, not a universal document type or the size of the original paper. A label reading 16 mm should be recorded alongside carrier form, layout, polarity, and any known reduction ratio.

A common microfiche sheet is approximately 105 × 148 mm. The number 105 mm needs context: it commonly describes a fiche dimension, while cataloging vocabularies can use dimensions in other ways. Write “105 mm microfiche” when the object is a fiche sheet rather than assuming that “105 mm film” names its carrier.

Note visual clues without overdiagnosing

Polarity describes tonal direction: positive images have dark information on a light background, while negative images have light information on a dark background. A collection can be mixed. Simplex and duplex describe one-up or two-up filming layout; they do not mean a paper scanner’s front-and-back setting. Cine and comic describe orientation on roll film.

Image marks, sometimes called blips, can help a legacy system count or locate frames. They are not the underlying document image and their meaning varies by collection. Record their presence and placement rather than assuming that every mark supplies usable document boundaries.

Create an identification note that is useful later

For each homogeneous batch, write down carrier, measured width or sheet dimensions, labels or targets, polarity, layout, reduction when known, condition observations, and intended use. Photographing or transcribing labels can be useful, provided the collection’s information-sharing rules allow it. Do not infer base, emulsion, generation, or deterioration diagnosis from age alone.

Fictional example — no PII: “Drawer B, jacket fiche, visible header ‘Series 4’, six channels, mixed strip lengths, two empty channels, negative polarity, reduction not marked.” This is more actionable than “old microfilm” because it separates observable facts from unknowns.

Common questions