Lignin

>brown color of the core paper of some acid free containers indicates it
>contains lignin.  Bleaching removes the brown -- most of it -- but not
>the lignin.  So obviously even with a light brown core, the dangerous
>lignin remains.

The color of the paper (board) is not an indication of lignin content.
Bleaching, during paper manufacturing, is a multi-stage process.
Chlorination, the first stage of most bleaching sequences, is intended
to delignify, rather than decolorize pulp. Chlorine reacts with the
non-carbohydrate component of chemical pulp to form a water-soluble
material called "chloro-lignin".  This material is removed in later
stages by the action of alkali and oxidants.  It is the later stages of
bleaching used (whether it's Alkaline extra ction, Chlorine Dioxide,
Calcuim Hypochlorite, etc.) that determines the color and brightness of
the pulp.

During chlorination, the degree of delignification depends mostly on the
nature of the cooking process.  Lignin removal is in direct proportion
to the amount of chlorine applied and cooking time.

Ralph Roessler \ Paper Technologies, Inc.

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                  Conservation DistList Instance 5:11
                   Distributed: Friday, July 19, 1991
                        Message Id: cdl-5-11-001
                                  ***