Charles Steinmetz (csteinmetz@redneck.efga.org)
Mon, 22 Feb 1999 06:10:16 +0000
It's the lignin in wood-pulp papers that causes yellowing, brittleness, and
the destruction of images applied to the paper, by decomposing into acids
and peroxides. No treatment has proven fully successful at preventing this
decomposition, and removing lignin from existing paper is a practical
impossibility. Buffering tries to mitigate the damage by providing a
reserve of alkali to neutralize the acidic decomposition products as they
form. Some alt processes may accidentally have a positive effect on paper
life, but if you use lignin-bearing paper there will be trouble in the
future.
Some wood-pulp papers are said to be lignin-free. Much, if not most, Ag
photo paper is made on lignin-free wood-pulp paper these days. I don't know
whether any sulfite papers make this claim, but it is certain that not all
sulfite papers are lignin-free.
So: if you are making images on paper and care about longevity, be sure to
get lignin-free paper. The surest way is to use 100% cotton paper.
Charles
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