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Cleaning that Harman Kardon Copper

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Posted on June 16, 2020 at 12:15:07
vanmeterannie
Audiophile

Posts: 357
Location: Eastern US
Joined: September 6, 2005



I have a late '50s HK Prelude that has quite a bit of discoloration (photo attached) and I've yet to find anything that will cut it. I test on the underside where there's no printing, and haven't gone near the faceplate-I don't want to risk losing what's left of the lettering so I've not really done anything remotely aggressive at all at this point since nothing seems to be cleaning it.

What do others use to make these shine again? More asking those who have actually done this and not looking for guesses since I suspect the obvious things like Brasso would remove the black ink.

 

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RE: Cleaning that Harman Kardon Copper, posted on July 11, 2020 at 08:57:02
Br3098
Audiophile

Posts: 255
Location: Southern California
Joined: December 23, 2009
 THere used to be a product called Tarn-X that was supposed to be a wipe-on product for silver and copper. I haven't seen it in years but I believe it's still available.

The face plate is not pure copper but a copper/tin wash. It was supposed to be resistant to corrosion. If it's tarnishing now (as opposed to just being dirty) your cleaning it is just going to cause it to re-tarnish pretty quickly. If you can get it pretty clean you might want to spray a clear lacquer over it. Remove the top cover, knobs and mask off the pots, switches and mask all areas you don't want sprayed. Spray very lightly; two thin or more thin coats are better than one glob (technical term).


I would avoid anything that requires scrubbing or especially buffing if you want to have any chance to preserve the lettering.

 

RE: Cleaning that Harman Kardon Copper, posted on June 16, 2020 at 22:23:19
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 I would use Simichrome polish with a buffing wheel... or Neverdull. Simichrome is well-known by watch repairmen.
The Mind has No Firewall~ U.S. Army War College.

 

RE: Cleaning that Harman Kardon Copper, posted on June 16, 2020 at 17:30:08
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 Yes, anything remotely abrasive, including toothpaste, is out. Try lemon juice, on the reverse side. The combination of citric and ascorbic acids frequently "cuts" through tarnish to clean metal.


Eli D.

 

RE: Cleaning that Harman Kardon Copper, posted on June 17, 2020 at 07:17:40
vanmeterannie
Audiophile

Posts: 357
Location: Eastern US
Joined: September 6, 2005
 I tried lemon juice with salt last night and, while it quickly removed the tarnish, it wasn't consistent, like a swatch of glowing pink copper but right next to it a patch that didn't come clean at all, despite being rubbed the same way/amount.

I'm guessing I need to figure out a way to mix the salt better to keep it the same...I don't want to have to do any aggressive scrubbing around the lettering when I get there.

 

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