---------------- ------------------- --------------------------------------- Property NISO ISO --------------------------------------- ANSI Z39.48-1992 ISO 9706 ISO/DIS 11108 "permanent" "archival permanent" ---------------- ------------------- ------------------ ------------------- pH 7.5-10 (u)* 7.5-10 7.5-10 7.0-10 core (c)** Alkaline reserve 2% minimum 20 g/kg CaCO3 20 g/kg CaCO3 Kappa number 7 5 5 (maximum) Tear measure 5.25 mNm²/g (u) 70 g/m²:350 mN 70 g/m²:350 mN 3.50 mNm²/g (c) 25-70 g/m²:r=6w-70 25-70 g/m²:r=6w-70 r = tear resistance r = tear resistance w = weight w = weight Other physical none none MIT folding properties endurance 2.18 Other chemical paper stock - no none paper stock - if properties more than 1% lignin other than cotton, linen or ramie must state content and percent ------------------------------------------------------------------------------ * (u) signifies an uncoated paper ** (c) a coated sheet
The pH and alkaline reserve requirements ensure that the paper is not acidic and will not become acidic over time. The kappa number requirement ensures that the paper is well-bleached, and therefore less likely to deteriorate due to oxidizable functional groups. And the tear index or tear resistance (as well as the folding endurance) is a measurement of strength which seems to predict fairly well an alkaline paper's durability under accelerated aging conditions.
Continue to Appendix 4: NARA Bulletin 95-7
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