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Subject: Lead corrosion

Lead corrosion

From: Diane Charlton <d.m.charlton2>
Date: Monday, July 5, 1999
Just a few brief thoughts regarding corrosion of Lead (?) toy

    1.  As you seem to be well aware, organic acids (off gassing
        from wood, cardboard) are particularly detrimental to Lead
        and Lead alloys.

    2.  In respect of other causes:

        I don't feel that casting faults would be a major problem in
        this instance;

        In respect of composition, they are probably lead rather
        than an alloy, although pewter (Pb/Sn) for example would be
        more prone to corrosion (bimetallic;

        I suspect that the cause of corrosion patterns in specific
        groups is due to poorly or thinly applied paint (ie. the
        same person probably painted the same group of soldiers),
        this would in turn reduced any barrier protection from
        moisture and organic acids.

    3.  Personally, I would not actively treat these objects unless
        you have lots of time and a large budget. Instead, your
        display could, for example, include a short paragraph on how
        the public should store their own collection, and point out
        that this collection has suffered some deterioration and the
        also the possible causes. (The corrosion process is also
        part of the objects history!).

    4.  Preventative conservation:

        This seems the best way to ensure that the toys do not
        deteriorate any further and probably the best use of

        As you do not have any humidity control for display purposes
        (who does?), then I suggest that you consider ways to buffer
        the objects from the environment. For example, select a
        display case (not wood) which is or could be sealed in some
        way. Create a false bottom (an inside compartment) and
        ensure that you include sufficient self-indicating silica
        gel, and a humidity control strip which is visible without
        having to continually open the case. Try to ensure that the
        RH is below 20%.

That all I can think of at present. I hope my thought are of some

Diane Charlton
Honorary Research Assistant
Conservation Unit
Department of Archaeological Sciences
University of Bradford

                  Conservation DistList Instance 13:6
                  Distributed: Wednesday, July 7, 1999
                        Message Id: cdl-13-6-004
Received on Monday, 5 July, 1999

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