Permanent records cannot be destroyed until you are notified that the microfilmed copy has met certification standards. The Reprographics Department of the University of Kentucky Libraries is a State-certified microfilm laboratory. Archival quality microfilm is 16mm or 35mm silver halide, polyester-base roll film. This medium will last hundreds of years if properly prepared and stored. Silver halide provides the clearest and most precise image.
Polyester is the most durable film base.
Roll format provides greater protection of the images. Other microformats include microfiche and microfilm jackets. Jackets are updateable, a particularly nice feature for offices that have records that accumulate sporadically over long periods of time. Medical records are a good example of these types of records. Neither microfiche nor microfilm jackets are considered an archival medium.