Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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m.m. system

A method of computing the basis weights of all grades of paper on a sheet size of 25 by 40 inches (1,000 square inches) and a 1,000 sheet count, i.e., the 1,000, 1,000 or m.m. system. The traditional writing paper basis weight of 20 pounds (17 X 22�) becomes 107 pounds on an m.m. basis (25 X 40�), while regular 60-pound book paper (25 X 38�) becomes 126 pounds, and so on. The m.m. system, which originated in the 1920s, is not in general use but printers, paper buyers, as well as others, often find it advantageous to use. In applying the m.m. system, a conversion chart is used which lists various grades with their traditional basis weights and corresponding m.m. factors. (17 , 320 , 329 )

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