Alum mordant for paper marbling

There is a discussion going on on the calligraphy list concerning
the use of alum as a mordant for marbling paper.  Some of these
people are using the traditional carragheenan size and watercolors;
some are using methyl cellulose and acrylic paints; some are using
combinations of the above. Their concern is for the effect that the
alum may have on the longevity of the paper; questions have arisen
as to whether deacidification with Wei T'o would be of any use after
the paper has dried.  Someone has mentioned that the use of ox gall
as a dispersant may be what has counteracted the acidity of the alum
in historical papers.  Anyone who could provide a clear layman's
explanation of the interactions between paper and alum and of the
necessity or not for treating the paper after marbling would receive
the undying gratitude of 600 calligraphers.  I will forward any
replies.  In most cases the paper used can be assumed to be
acid-free but not buffered.

Anne T. Lane
Curatorial Assistant
Museum of York County
4621 Mount Gallant Road
Rock Hill, SC 29715
803-329-2121, ext 104

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                  Conservation DistList Instance 12:67
               Distributed: Wednesday, February 17, 1999
                       Message Id: cdl-12-67-015
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