Faded ink

With regard to the question put forth by Kathie Bordelon regarding
darkening of faded iron gall ink:

There were several methods employed in the nineteenth century to
darken faded iron gall ink; however, they are injurious to the ink
and the paper.

One method that is not injurious to the document is the ammoniacal
vapour chamber (using only analytical grade ammonia).  In some
cases, the vapour may induce the interaction of trace tannins and
trace metallic salts to the extent that darkening does occur.  This
approach causes only temporary darkening; however, it may allow
enough time to photograph the information of the text before the
darkened text once again fades.

In the nineteenth century, it was a common practice to spread tannic
acid (usually gallnut solution) on the surface of a faded document
using a feather to deliver the solution.  The metallic salt (usually
ferrous sulfate) was often present in excess in the faded writing.
When the solution of tannic acid met with the excess metallic salt
in the handwritten text, darkening occurred.  The down side,
obviously, is that the tannic acid is injurious to the paper system!
No one would recommend treating a document in this way.

It is also important to note that there were many experimental ink
formulations in the United States during the second half of the
nineteenth century.  Iron gall ink, though common, is only one
possible ink formulation.  There are a variety of other black, blue
and violet ink colorants of that period that are vulnerable to
fading.  If the ammoniacal chamber does not darken the ink, it is
possible that you are dealing with something other than iron gall
ink.

Rachel-Ray Cleveland
Conservation of Paper
Baha'i World Centre
PO Box 155
31 001 Haifa, Israel
+972 4 835 8057
Fax: +972 4 835 8591

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                  Conservation DistList Instance 10:84
                  Distributed: Friday, March 28, 1997
                       Message Id: cdl-10-84-004
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