alkaline reserve
A buffer, or reserve, of an alkaline substance
added to a paper for the purpose of counteracting
any acid which may be introduced into it
subsequent to DEACIDIFICATION .
Soaking paper in a solution of calcium bicarbonate
or magnesium bicarbonate adds a small amount of
calcium or magnesium carbonate which neutralizes
any acid present and also provides a reserve to
counteract acid which may enter the paper at some
future time. (The bicarbonates are converted to
the carbonates during the drying of the paper,
with the liberation of carbon dioxide.) The
treatment is effective only as long as free alkali
remains. Papers which are to remain acid free for
long periods of time, e.g., 500 years, should have
approximately 3% precipitated carbonate by weight
of paper. (198 )
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