Chloramine T and stamps

Barry Knight <barry [at] eng-h__gov__uk> writes:

>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....
>    and the stamps look better, if the stains aren't there.
>...
>    What I'd like to know is:
>    (a)  Is using chloramine-T likely to cause long-term problems?

It is not  new that this list gets once in a while a request for
"how to treat this or that object and how to practice a certain
technique, etc." and this time it is how to practice stain removal from
philatelic material. Personally I feel somehow very doubtful how to
relate such requests that comes from unqualified person and this is
not the case of "keeping secrets" or so, I would like to open this
case and to hear other opinions in this matter.

However, I believe I should comment on the following issue from my
best knowledge as I take this request as a consultation.

Stain removal or bleaching with Chloramine T is a relative old
oxidizing technique which was very popular 15 years ago. It was
believed to be a better bleach than hypochlorites since it had a
milder visual effect on paper than other oxidizers (potassium
permanganates, chlorites etc.). However, research proved to show it
is very hard to get rid of some of the chlorite compounds from the
paper and this means that the chlorites in the paper are bad news!

Today, the tendency toward stain reducing is more into using
reducing agents as peroxides, borohydrides and ozonization (which
would not leave active materials and traces into the object). But, the
real fashion is light bleaching. It is important for you to know that
reducing only iron pigmentation does not provide a good result
(after a while stains can reappear as before). It is important to
block or stabilize the iron with chelating materials (EDTA--ethylene
diaminetetracetic acid) before bleaching takes a place.

Now philatelic material is a very delicate material which has is own
specialty in paper conservation. This means: the paper, the printed
colors, signatures and so, are very delicate to any optional
treatment. This suggests some experience and knowledge when decision
making takes a place . Now I strongly suggest that you address a
good paper conservator with great deal of experience with philatelic
material if your collection is dear and important to you.

Michael Maggen
Senior paper conservator
The Israel Museum Jerusalem
Israel

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                  Conservation DistList Instance 11:88
                    Distributed: Friday, May 1, 1998
                       Message Id: cdl-11-88-005
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