1.1 This guide covers offset and book papers, both coated and uncoated, used in the preparation of permanent records. Permanent records usually are expected to last several hundred years in a records repository, with little change in properties that affect readibility or handling, although some records are expected to have shorter lifetimes.

1.2 Acidic materials incorporated in paper during manufacture (for example, rosin-alum sizing) contribute to deterioration. It has been shown (1, 2, 3, 4, 5) that the life expectancy of uncoated papers is an approximate function of the pH of an aqueous extract of the paper.

1.3 The following would be expected to contribute significantly to the life expectancy of books and documents: the use of papers with controlled acidity or of papers manufactured under neutral or alkaline conditions, especially papers with a calcium carbonate filler that absorbs acidic gases from the atmosphere or can neutralize acidic materials formed in the aging of paper.

1.4 Three pH levels reflecting three levels of life expectancy are outlined in this guide. As one cannot rely on pH alone as an indicator of stability, minimum retentions of properties after accelerated aging at 90°C and 50% relative humidity are suggested for the three levels of life expectancy.

1.5 In selecting papers for permanent records, papers with acceptable durability are evaluated for life expectancy through accelerated aging.

1.6 This guide should be used in the purchase of paper for permanent records.

1.7 This guide is based on the use of fiber sources used in the production of paper that contains no more than 1% lignin for papers used in archives, libraries, and other permanent records. However, under proper conditions (see X1.8) paper containing more than 1% lignin may be employed for many other end uses in paper for records that are required to have a substantial life expectancy.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.