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Best way to clean Copper?  Heavy Tarnish.
Best way to clean Copper?  Heavy Tarnish.
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Old 13th March 2018, 05:09 PM   #1
TankAudio is offline TankAudio
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Default Best way to clean Copper? Heavy Tarnish.

Hey Everybody,

I have a great product called Simichrome, made by Happich, that I use to remove surface oxides and to clean frets on stringed instruments. I recently experimented with its use on an old Eico Amp face plate. Take a look at the pictures, they say more than I can.

The Simichrome does remove the golden color, which I would have been happy to leave if it weren't for the dark black tarnish spots. These black tarnish spots appear to reside in the metal on a deeper level. Can I wet sand with the grain? How about a clay bar, typically used to remove surface oxides from automobiles? Any suggestions from prior experience would be appreciated. I will likely decide to clean the cage as well, since the color of the face plate will look foreign after it has been refreshed.
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Old 14th March 2018, 02:04 AM   #2
chrisb is offline chrisb
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No matter what product / process you find successful in removing tarnish, I think your prime challenge will be to do so without damage to silk-screened lettering etc
You’ll often find they’re not as durable as you’d like
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Old 14th March 2018, 02:53 AM   #3
boswald is offline boswald  United States
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Best way to clean Copper?  Heavy Tarnish.
Simichrome is a very mild abrasive, in ancient times we used it to 'run in' new cones and races for track and race bikes.
You might want a reducing agent, anything from cleaning strength vinegar to phosphoric acid or oxalic acid.. Lime-a-Way is phosphoric, Barkeepers friend is oxalic. Bon Ami is milder than simichrome, it is feldspar powder, just a little stronger than toothpaste.
Your photo does not look like copper, it looks like a brass-coloured steel, funny lighting?
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Old 14th March 2018, 07:54 AM   #4
TankAudio is offline TankAudio
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About the lighting, I chose this photo as it didn't accent the glare from the polish. I'll take another and re-post.

The silkscreen is embedded in recessed engraving grooves, if I'm careful I think there won't be any friction from polishing cloths and grits, etc. The chemicals may still affect the silkscreen.
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Old 14th March 2018, 10:47 AM   #5
tapestryofsound is offline tapestryofsound  Scotland
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Quote:
Originally Posted by TankAudio View Post

The silkscreen is embedded in recessed engraving grooves, if I'm careful I think there won't be any friction from polishing cloths and grits, etc. The chemicals may still affect the silkscreen.
Hi TankAudio,

You could try using white vinegar (acetic acid) or CocaCola (phosphoric acid) to remove the tarnishing. Painted lettering within the engravings can be retouched with black boot polish.

An alternative, depending on aesthetic sensibility, is to simply clean off the surface grime with a damp cloth then leave it as it is :-)

Kindness tapestryofsound
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Old 14th March 2018, 11:42 AM   #6
Maupastor is offline Maupastor  Portugal
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I second the suggestion in the previous post, it looks beautiful as it is.
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Old 14th March 2018, 11:44 AM   #7
scottjoplin is offline scottjoplin  Wales
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What they call patina, or verdigris in the trade
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Old 14th March 2018, 07:48 PM   #8
russc is offline russc  England
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Option 1 - If it is copper or brass, you could abrade until the marks were out.
Trouble is, the pitting may be as deep as the lettering.
Option 2 - Spray paint the panel then re-highlight the lettering.
Option 3 - live with it.

I suspect it's an aluminium panel.
Aluminium corrodes in contact with steel - witness the high corrosion around the steel screw.
Look up aluminium cleaning on the web and decide how extreme you are prepared to go.
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Old 15th March 2018, 02:44 AM   #9
PRR is offline PRR  United States
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I have not touched an EICO plate in decades.

I do recall they were getting blemishes even then.

Is it really Copper/Brass? Try the magnet. I'd bet a steel nickle they were steel with a light copperish flash. Any attempt to "make new" will probably have to go all the way through the coppertone, start in on the iron rust, then be re-plated. You will surely lose the graving fill; without great care you may damage the engraving.

But wait for somebody with more EICO experience before you give up and apply the belt-sander. There may even be different techniques over the EICO years.

If it IS copper, my usual brew is vinegar and salt. The exact electrochemistry turns out to be obscure, but it will remove copper tarnish over time. Flood a paper towel with vinegar, salt it heavily, slap it on the copper, rub a bit. Let set an hour. Rinse, examine, repeat. Any clear-coat probably has to come off first.

When you get gleaming Copper, DRY WELL QUICKLY! Raw copper will tarnish in hours if damp.

Flitz is another respected copper polish (after you get the yuck off).
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Old 15th March 2018, 10:09 AM   #10
lowtherdream is offline lowtherdream  Canada
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Check the everbritecoatings web site. They compare different diy options and give results. They have a great line of products for different metals, from cleaning to protecting.
Give them a call and send pictures
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