ANSI AIIM MS23-2004 pdf download PRODUCTION, INSPECTION, AND QUALITY ASSURANCE OF FIRST-GENERATION, SILVER MICROFORMS OF DOCUMENTS
4.3 Life expectancy At one time, film life was divided into two categories, archival and non-archival. The term “archival” was used to mean forever, and “non- archival” was used to mean something short of forever. A more meaningful designation, “life expectancy”, often shown as “LE”, has been devised and specifically refers to the number of years that filmed information can be retrieved under a certain set of manufacturing, processing, and storage conditions. At present, only properly processed and correctly stored silver halide film on polyester base has an LE rating of 500 years (LE 500), whereas acetate- based silver halide film can have LE ratings of 1 00 years. A responsible decision-maker will use the desired LE rating as a critical factor in selecting system characteristics. International, federal, state, and local regulations as well as commercial contracts and specifications may dictate that specific LE requirements are met.
4.4 Number of generations Each successive film copy of a document, beginning with the film produced in the camera, is referred to as a specific generation. For example, the camera master is referred to as the first generation. A copy made directly from the camera master is a second generation. A copy made from the second generation is a third generation, and the like. The film produced in a camera is given any of several names: camera master, camera negative, original master, camera original, original camera negative, and preservation master. Frequently this first- generation film is stored as a master from which copies are produced. Although maximum protection must be given the first-generation master, a small number of copies (fewer than five copies) may be produced from it. If a large number of copies are needed, then an intermediate (second-generation) version should be produced. Multiple copies can then be printed from this second-generation printing negative. However, as the number of generations increases, image quality deteriorates and contrast increases rapidly. Producing more than four generations proves neither practical nor desirable. As the number of generations to be produced increases, overall quality level of the camera master must increase.
Regardless of polarity, with each generation the side of the film through which the image can be properly read (right-reading) alternates. See figure 1 . Images in the first generation are readable through the shiny base side of the film. The second generation reads correctly through the dull emulsion side of the film. The third generation can be read through the base side. Correct identification of emulsion sides is critical when succeeding generations are produced because proper duplication is only possible with emulsion-to-emulsion contact.