Chloramine T and stamps

I am posting this message on behalf of a colleague, Sebastian Payne.

    I'm working on a series of stamps issued by South Africa between
    1926 and 1954, many of which are a little foxed and/or generally
    a bit yellowed.  Soaking these stamps briefly (1-5 minutes) in
    water doesn't appear to damage inks or paper, but doesn't have
    much effect on the staining, which I'd like to remove because
    it's easier to look at the printing details I'm interested in,
    and the stamps look better, if the stains aren't there.

    Stamp dealer sell a product called "Foxit" which they say cleans
    stamps well without any long-term problems; the active
    ingredient is said to be Chloromine T (sic!).  I've tried this
    out on a number of unimportant stamps, and it certainly works.
    What I've been doing is to soak the stamps I'm treating in water
    first for 5 minutes, then in dilute "Foxit" for 5-10 minutes,
    and then rinse in water again for a couple of hours.  The foxing
    and yellowing disappear, and, when compared under low-power
    microscope with untreated halves of the same stamp, paper, inks
    and post-marks all appear to be undamaged.

    What I'd like to know is:

    (a)  Is using chloramine-T likely to cause long-term problems?

    (b)  If this isn't certain--if, for instance, it depends on the
    ink and/or the paper--is there any way I can test to see whether
    long-term problems are likely to happen?

    (c)  Is there a better alternative treatment?  (lots of stamps,
    but they are small, so expensive chemicals isn't a problem but
    large amounts of time spent on individual stamps would be)

    (d)  Or would it be much better not to think of treating the
    stained stamps?

    Sebastian Payne
    spayne [at] eng-h__gov__uk

Barry Knight
English Heritage
London

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                  Conservation DistList Instance 11:87
                  Distributed: Tuesday, April 28, 1998
                       Message Id: cdl-11-87-011
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