Faded ink

Among the responses to this inquiry it has been suggested that
ammonia fumes be used to temporarily darken faded iron gall ink;
this will not work, although ammonium sulfide will work.

C.E. Waters, in the U.S. Dept. of Commerce/National. Bureau of
Standards circular C426, "Inks," 1940, pp. 28-30 discusses the issue
and problems associated with potential solutions.  He states:

   "A disadvantage of any chemical treatment is that iron is found
    in practically everything.  Paper and dust contain it, and if
    the document has been much handled, it will have a surface
    coating, containing iron, that comes from dirty hands.  The
    chemicals are not selective in their action, and thus the
    writing is restored as dark lines upon a less dark and unevenly
    colored background.  If the entire sheet of paper is treated
    with gallic or tannic acid, it will become further stained in
    the course of time, because these acids darken by oxidation.

   "If possible, the excess acid should be washed out by immersing
    the treated paper in pure water for a short time, and then
    drying it."

Waters does not mention that iron is a common contaminant of alum,
used with rosin in sizing paper, nor does he mention staining of
paper as tannic acid reacts with the gelatin of gelatin/glue sized
papers, or that tannic acid, itself, acts as a dye.

As there is no sound solution (safe photographic ones) to this
problem, it is best to leave well enough alone.

Jack C. Thompson
Thompson Conservation Laboratory
7549 N. Fenwick
Portland, OR  97217
503-735-3942

                                  ***
                  Conservation DistList Instance 10:85
                  Distributed: Monday, March 31, 1997
                       Message Id: cdl-10-85-001
                                  ***