Silver Halide Film

• Silver Halide is the film type used in the camera to make the master film.
• Silver Halide is the most light sensitive of all the films used, hence it can record a greater variance of density and contrast in the original image.
• Silver Halide is the only film that is considered archival.
  • Silver-halide print films are of two types: Polarity reversing and direct-duplicating.
  • Silver-halide film should not be stored with other kinds of film.
  • Best film type for census records.

Diazo Film

• The Diazo process is used exclusively for making copies of the master film. It is not sensitive enough to be used as a camera negative film. The process has been used since the 1920's.
  • Diazo is a polarity maintaining copy. (i.e. negative to negative.)
  • Do not use in strong sunlight. Sunlight contains ultraviolet light and will ruin the film even after processing.

Vesicular Film

• Vesicular films became popular not only because of the ability to reverse the image but also because it can be handled in daylight and process using a dry thermal process. The image is comparable to silver when projected on a reader screen.
  • Image reversing
  • Can be handled in daylight.
  • Best film type for newspapers.

Heritage Microfilm, Incorporated
1450 Boyson Road, Building B
Hiawatha, Iowa 52233