This specification covers bond and ledger papers used in the preparation of records and documents that are expected to have maximum, or substantial, life expectancy.
It has been shown (1, 2, 3, 4, 5)(Footnote 2) that life expectancy is at least an approximate function of the pH of an aqueous extract of the paper. Three pH levels, reflecting three levels of life expectancy, are specified.
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 and can neutralize acidic materials formed in the aging of paper.
This specification is based on 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 X1.5), paper containing more than 1 % lignin may be employed for other end uses in paper for records that are required to have a substantial life expectancy.
As indicated in Appendix X1.4 and X1.5, this specification may be used as a guide.
Footnote 2 - The boldface numbers in parentheses refer to the list of references at the end of this specification.