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 Forum index » DIY Hardware and Software
removing rust/corrosion from copper key contacts
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patrickvf1976



Joined: Aug 08, 2011
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PostPosted: Mon Mar 04, 2013 5:52 pm    Post subject: removing rust/corrosion from copper key contacts
Subject description: what works best?
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I'm trying to fix up an old synth (Realistic/Moog MG-1) and half of the thin metal contacts are extremely corroded. I'm hoping that someone can suggest/recommend some easy/safe methods (other than scratching it off and permanently ruining the contacts that way) that provide some reasonably good results. Thanks ahead - Patrick
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scriptstyle



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PostPosted: Mon Mar 04, 2013 8:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

I used a a good No.2 pencil eraser to clean the poly6 contacts
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patrickvf1976



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PostPosted: Mon Mar 04, 2013 9:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

hmm dunno if that's gonna work in my case because the gunk/corrosion is very stubborn and the ends of the contacts that actually touch the wire seem very delicate. That's why I'm looking for an alternative method to minimize the risk of damaging the contacts, but at least it beats scratching it off with a screwdriver.

Would it work if I soak them in vinegar overnight? Maybe it'll make things easier? Or would it actually attack the metal?
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EdisonRex
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PostPosted: Tue Mar 05, 2013 1:09 am    Post subject: Reply with quote  Mark this post and the followings unread

patrickvf1976 wrote:
hmm dunno if that's gonna work in my case because the gunk/corrosion is very stubborn and the ends of the contacts that actually touch the wire seem very delicate. That's why I'm looking for an alternative method to minimize the risk of damaging the contacts, but at least it beats scratching it off with a screwdriver.

Would it work if I soak them in vinegar overnight? Maybe it'll make things easier? Or would it actually attack the metal?


The salt-and-vinegar method for copper will actually make the problem worse as it strips the copper to such a clean state that it will very quickly oxidize again. You would need to immediately treat the copper with antioxidant more or less as soon as you got it out of the wash.

gunk is not necessarily corrosion, either. Old beer, cigarette smoke, etc can make a right mess. For gunk removal, try 99% isopropyl (the kind you get as a cleaning solvent, not the drugstore kind), it is not likely to damage the copper itself.

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patrickvf1976



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PostPosted: Wed Mar 06, 2013 6:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

hmm sounds like the vinegar would make it easier to clean up if I don't soak it for too long. Would something like CLR work for breaking up/loosening corrosion without external force? Glass cleaner? What else may or may not work and is in the $2-$10 range?
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scriptstyle



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PostPosted: Wed Mar 06, 2013 11:49 pm    Post subject: gb Reply with quote  Mark this post and the followings unread

if it is already that corroded i would stay away from vinegar, vinegars Ph level fluctuate and I don't trust that. I would use Iso 99% if possible and a teflon pad. then move on to a good eraser.
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kkissinger



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PostPosted: Thu Mar 07, 2013 7:16 am    Post subject: Reply with quote  Mark this post and the followings unread

EdisonRex wrote:
For gunk removal, try 99% isopropyl (the kind you get as a cleaning solvent, not the drugstore kind), it is not likely to damage the copper itself.


As an alternative, he could probably use Everclear (180 proof grain alchohol) to clean the contacts.

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EdisonRex
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PostPosted: Fri Mar 08, 2013 4:38 am    Post subject: Re: gb Reply with quote  Mark this post and the followings unread

scriptstyle wrote:
if it is already that corroded i would stay away from vinegar, vinegars Ph level fluctuate and I don't trust that. I would use Iso 99% if possible and a teflon pad. then move on to a good eraser.


The other bigger problem is you can't just use vinegar, you don't get the proper chemical reaction, you need salt (sodium chloride); the chemical reaction involves converting copper oxide into positively charged copper ions in the solution; so you're actually removing some of the copper, which you can't put back on with the same solution you use to take it off. This is why I'm seriously not recommending this method. In addition, the negatively charged surface of the copper after this treatment will oxidise very quickly, so it doesn't even do much good.

Kevin is also correct, in fact, any solvent should help, Everclear being a decent all-purpose solvent that won't evaporate quite as fast as Isopropyl/Isopropanol or 1,1,1 Trichlorethane. Plus you can probably find a small bottle of the stuff more easily than the others.

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analog_backlash



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PostPosted: Fri Mar 08, 2013 7:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Ah, I finally feel like I'm in my comfort zone, being a chemist (admittedly a non-working chemist at the moment). Very Happy

EdisonRex wrote:
The other bigger problem is you can't just use vinegar, you don't get the proper chemical reaction, you need salt (sodium chloride); the chemical reaction involves converting copper oxide into positively charged copper ions in the solution; so you're actually removing some of the copper, which you can't put back on with the same solution you use to take it off. This is why I'm seriously not recommending this method. In addition, the negatively charged surface of the copper after this treatment will oxidise very quickly, so it doesn't even do much good.


Any method of cleaning copper, whether it is chemical or mechanical will result in the loss of copper from the surface. The only way that you can convert an oxide coating (if it is an oxide coating, that is) into copper again, would be to reduce it (e.g. by heating it in a stream of hydrogen). Apart from the total impracticality of this method, it's also very dangerous if you don't know what you're doing!

I would agree that aggressive chemical methods lead to a surface which will re-oxidise very quickly. This is because a chemical clean will lead to a greater surface area of copper being exposed to the oxygen in the air (mechanical cleaning only exposes the very top surface, whilst chemical methods will expose more of the microscopic "nooks and crannies" not reached by your buffing cloth).

Most organic solvents will help to remove the residue, but not have any chemical effect on the copper, so use whichever you prefer, have handy etc. I wouldn't use a chlorinated compound (e.g. 1,1,1-trichloroethane) partially because of their alleged carcinogenicity (it depends on who you believe) but mainly because most were banned under the Montreal Protocol because of their ozone depleting properties Twisted Evil I used to produce safety data sheets in my last job, so I was dealing with this kind of thing all the time (God, it was tedious).

Gary
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prgdeltablues



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PostPosted: Fri Mar 08, 2013 7:22 am    Post subject: Reply with quote  Mark this post and the followings unread

One thing you might consider if you do end up with a chemically clean copper surface, that would therefore re-oxidise quickly, is to silver plate it. There are various solutions available to do this, such as:

http://www.kernowcraft.com/products/silversmithing-and-tools/sundries/silver-solution-C125/

Not cheap, but will do a lot of surfaces - including household cutlery, jewellery, etc (which is what I use it for). Note this isn't just your usual silver polish, which removes oxide, it adds pure silver to the surface.

Peter
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analog_backlash



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PostPosted: Fri Mar 08, 2013 8:27 am    Post subject: Reply with quote  Mark this post and the followings unread

prgdeltablues wrote:
One thing you might consider if you do end up with a chemically clean copper surface, that would therefore re-oxidise quickly, is to silver plate it. There are various solutions available to do this, such as:

http://www.kernowcraft.com/products/silversmithing-and-tools/sundries/silver-solution-C125/

Not cheap, but will do a lot of surfaces - including household cutlery, jewellery, etc (which is what I use it for). Note this isn't just your usual silver polish, which removes oxide, it adds pure silver to the surface.

Peter


That's a possibility, although even silver tarnishes (mainly due to sulphide formation). Gold plating would be great, but horrendously expensive! I've thought about nickel plating but never got round to experimenting with it. Nickel salts are also suspected carcinogens and toxic to the environment, so they're not very green either (except that they usually are green).

Gary

P.S. I used to order stuff from Kernowcraft years ago (whilst I was still at school), as I used to be into gemstone polishing/minerals/fossils etc. I'm still interested in geology, but I prefer to make weird noises now...
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