RE: Coating brass mounts

["Steve Short" <Steve.Short@pam.org>]

Hi Ben,

I like the natural brass sometimes, too, if the mount won't be out for a
long, long time.  Keep in mind, though, that if there is an electron
transfer between the solder and the brass, you'll get an ugly fluffy
growth on the surface of your mount.  That will happen faster in cases
with artifacts that have been in the ground or under the ocean, or if
there is any moisture in the air around the mount.  Essentially --
moisture and salt, which act as an electrolyte will help this process
along.

I have had good results using B-72 to retard any salt and/or moisture
from reaching solder joints.  If you can manage to remove any roughness
or pitting on the surface of the metals, you will be able to get a
pretty good seal.  You won't have to coat the entire mount, either, if
you want to allow the surface of the brass to patina naturally.  An
all-over coating of B-72, however, will keep your mount looking like new
brass for a long time.

I hope that helps.

Steven Short
Associate Preparator
Portland Art Museum
1214 SW Park Ave
Portland Oregon, 97205
503.276.4269

-----Original Message-----
From: pacinlist-bounces@pacin.org [mailto:pacinlist-bounces@pacin.org]
On Behalf Of Benjamin Peters
Sent: Friday, July 13, 2007 8:56 AM
To: pacinlist@pacin.org
Subject: Coating brass mounts

Hello,

What are people's thoughts and knowledge about the need to coat brass 
mounts.   For our last exhibit we decided to leave all our brass mounts 
their natural brass color rather than painting them with acrylics.
There 
was no direct contact between the mount and the artifacts.  We always
use a 
barrier of either Polyolefin tubing, felt or Volara.  However, some
people 
have expressed the concern that the mounts should still have at least
been 
sealed with a clear coat of something like B-72.  Our thought had been
that 
the reason we were using brass is for its high corrosion resistance and 
besides it darkening slightly from when it was first made it would pose
no 
threat to the artifact.

We would like to continue to not have to paint the mounts if possible.
Any 
light on the subject would be helpful.

Thank you,
Ben




Benjamin Peters
Principal Museum Preparator
Phoebe Hearst Museum of Anthropology
bpeters@berkeley.edu
510-643-1191 ext. 2
http://hearstmuseum.berkeley.edu