Magnetic closures

Searching the Cons DistList archive for information on the
durability of magnetic closures, I only found a short May 1994
thread that addressed concerns about the self-stick adhesives and
the danger to nearby magnetic media. My concern is the durability of
the magnets. Informal inquiries to conservators and manufacturers
have produced no verifiable or quantified information. Anecdotal
reports indicate that flexible magnetic material of the type
normally cut into pieces for container flaps may lose their holding
power within just a few years.

Is there any documentation of longevity tests on these materials,
with a comparison of different brands?  Is there a parameter in
standard nomenclature that addresses the durability of magnets? Does
it make a difference to longevity whether it is magnet to magnet or
magnet to metal? My concern is that in 500 years or less the
closures will not work. This information is needed both for archival
containers for existing works and in the design of new works.

Richard


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                  Conservation DistList Instance 18:23
                 Distributed: Monday, November 22, 2004
                       Message Id: cdl-18-23-028
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