[BCMA] should we polish brass and copper?

[Moderated BCMA subscriber listserv.]

That’s great advice Nikki.  I’d just add that polishing is always a destructive process, removing metal along with the corrosion.  Even for solid copper, brass and silver, you will lose surface decoration and introduce small scratches that can be disfiguring and can actually increase the likelihood and extent of further corrosion.  Best to leave it unpolished.  If polishing is absolutely necessary, then store/exhibit with scavengers such as Pacific Silver Cloth afterward, to inhibit further corrosion.  Otherwise, once you polish, you’ll probably have to keep polishing.

Kasey
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Kasey Lee       Senior Conservator  |  Collections, Care and Conservation

ROYAL BC MUSEUM
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From: bcma-bounces at lists.vifa.ca [mailto:bcma-bounces at lists.vifa.ca] On Behalf Of Moderated BCMA subscriber listserv.
Sent: Wednesday, July 24, 2019 7:48 PM
To: bcma at lists.vifa.ca
Subject: Re: [BCMA] should we polish brass and copper?

Hello Wendy,

This is something that is often debated between conservators and curators. At some point they should not get any darker. Once an even tarnish layer or patina forms on the surface they should remain the same colour as long as they are handled with gloves and not exposed to other contaminants. Metals are very sensitive to oils from our hands and as they will etch into surface and cause localized tarnishing.
I would not polish them because I like the tarnished aged look. Every time you polish something you are stripping a thin layer of the metal off. This is not a problem if it is solid copper, brass or silver. If it is only plated then at some point you will strip away all the copper/silver leaving the base metal to show through. Polishing can be very time consuming and will increase the chances of damage due to increased handling.
Saying that, if you have something that you know never would have been allowed to tarnish in its working life then you might wasn’t to keep it polished.

Sorry it’s not a clear yes or no, but hopefully some more food for thought!

Nikki Bose
Curator of Collections
Kelowna Museum
nbose at kelownamuseums.ca<mailto:nbose at kelownamuseums.ca>


From: bcma-bounces at lists.vifa.ca [mailto:bcma-bounces at lists.vifa.ca] On Behalf Of Moderated BCMA subscriber listserv.
Sent: July 24, 2019 10:29 AM
To: bcma questions
Subject: [BCMA] should we polish brass and copper?

The Greek Heritage Project Museum in Victoria has a number of "old", as up to 100 years old, brass and copper artifacts, mostly cooking and coffee pots. They are becoming darker as time goes on. We are back and forth about whether to clean and polish them or to  allow their age to show.
Part of the issue is that the polished items tend to then be very bright and lose some of their age.
The pictures may help.

Thanks
Wendy

Wendy Smylitopoulos
Curator
Greek Heritage Project Museum
4648 Elk Lake Drive, Victoria BC V8Z 5M1
<greekhpm at gmail.com<mailto:greekhpm at gmail.com>>
250 419-3151

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