Brass polishes

Clint Fountain inquired about which proprietary brass/metal polishes
to recommend to the general public.  This requires a long answer and
may spark some controversy, since we have to give the public some
straight answers or else we lose credibility.  On the other hand, we
should also encourage people to know when they have a historically
valuable object and it is in poor condition that they should find a
professional conservator who is available to assess and treat the
objects.  I would be willing to discuss this off list.

My short answer is that I use Simichrome polish as a final polish on
polished metals, after initial cleaning with other tarnish/corrosion
removal chemicals.  I remove the Simichrome residue with acetone
and/or mineral spirits.  It does contain approximately 13% ammonium
oleate, which is responsible for the ammonia odor.  Two other
paste-type metal polishes, Peek and Solvol Autosol, essentially
contain the same ingredients; only the colorants used differ.  My
decision to use this product was based on published silver polishing
research, evaluation of the MSDS and product literature, and
empirical experience.  I most damage done to metals by ammonia-based
polishes is due to the fact that people do not rinse them off and
completely remove the residues.  Perhaps a conservation
scientist/metallurgist has research data that elucidates how and
when the damage occurs: immediately upon application of the ammonia,
or over a period of time if allowed to seep into the porosities of
the alloy.  I suppose the effect would depend upon the alloy
composition, degree of surface damage, etc..

Paul S. Storch
Objects Conservator
John and Martha Daniels Objects Conservation Laboratory (JMD-OCL)
B-109.1, Minnesota History Center
345 Kellogg Blvd West
St. Paul, MN  55102-1906
612-297-5774
Fax: 612-297-2967

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                  Conservation DistList Instance 11:59
                  Distributed: Friday, January 9, 1998
                       Message Id: cdl-11-59-004
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