Brass

Terry Weisser <tweisser [at] thewalters__org> writes

>Wyatt Yeager <weyeager [at] comcast__net> responded
>
>>Have you considered a pre-soak in Sodium Sesquicarbonate or Sodium
>>Hexametaphosphate followed by a treatment with BTA or Incralac? ...
>
>Although sodium sesquicarbonate was recommended at one time for
>treatment of copper alloys, it is no longer considered safe.  This
>double-carbonate removes copper from the metal surface (as does
>ammonia).  Also, brass is vulnerable to dezincification from both
>alkaline and acidic solutions, so care must be taken with any
>cleaning product.

I am very interested in what method you would suggest for the
treatment since ruling out sesquicarbonate? We have had complete
success with sodium sesquicarbonate treatments going on 40+ years
and still stable. I have used it exclusively in cupreous numismatic
conservation where success or failure is measured on the microscopic
scale. Any recommendations would be highly appreciated.

Wyatt Yeager


                                  ***
                  Conservation DistList Instance 22:51
                 Distributed: Wednesday, March 11, 2009
                       Message Id: cdl-22-51-005
                                  ***