Lignin and paper permanence

This may not be a "more knowledgeable" comment, but it has often
interested me:

   "It has been observed that many papers containing groundwood
    exhibit poor permanence. The reason for this behaviour is *not
    clear* because wood is a very stable material and, in the
    absence of decay, is known to endure as a structural material
    for many centuries. Some modification is possible in preparation
    of groundwood because the wood is subjected to instantaneous
    high pressure and shearing action and, possible, localized high
    temperature in the grinder or disk refiner. Access of gases or
    liquids into wood is possible because it is a porous material
    and has a large internal surface area. The area available for
    reaction would be expected to increase only moderately during
    the grinding operation."

        Browning, B.L. The application of Chemical and physical
        tests in estimating the potential permanence of paper and
        papermaking materials. in Preservation of Paper and Textiles
        of Historic and Artistic Value II, ed. John C. Williams,
        Amer. Chem. Soc., Advances in Chemistry Series, 164
        Washington D.C., 1977 p. 279

Mark Clarke
London
+44 941 101 251

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                  Conservation DistList Instance 10:99
                    Distributed: Friday, May 9, 1997
                       Message Id: cdl-10-99-002
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