Old, tarnished copper hookup wire - Page 1
Forum section: electronics / projects

author: mcovington
author_rank: Regular Contributor
timestamp: March 15, 2021, 11:23:17 pm
content: Much of my stock of copper hookup wire is 20 to 40 years old and is often visibly tarnished. My impression is that the tarnish makes the wire harder to solder and makes me distrust using it in any kind of solderless connector. Tinned wire is not affected. Should I get rid of the tarnished copper wire and replace it with fresh wire?

author: TimNJ
author_rank: Super Contributor
timestamp: March 16, 2021, 12:28:41 am
content: You can try some fine grit sandpaper, maybe about 1000. That’s worked well for me. Or, if you have any of those brass shavings/wool used for cleaning soldering iron tips, that might work okay.I’d just recommend against coarse grit sandpaper, as it may make the surface too rough, cause scratching/damage to your breadboard.

author: bob91343
author_rank: Super Contributor
timestamp: March 16, 2021, 05:25:36 am
content: Soldering flux, rosin type, works well.

author: archil
author_rank: Contributor
timestamp: March 16, 2021, 10:22:57 am
content: mechanical cleaning is important, before soldering.

author: mcovington
author_rank: Regular Contributor
timestamp: March 16, 2021, 01:44:25 pm
content: I know how to solder it if I have to, by using sandpaper and/or more flux. I am wondering if I want to keep putting up with this or replace some of my stock of wire. Is the conductivity of the wire itself impaired? I need to see what happens if I cut off a few feet of wire -- see whether it has tarnished a long way under the insulation or only near the ends.

author: SeanB
author_rank: Super Contributor
timestamp: March 16, 2021, 02:22:23 pm
content: Cut back a few feet and see, though likely it will be slightly tarnished. I had a lot of this, so took a pair of small cheap flat pliers and stuck a small strip of 800 grit wet and dry sandpaper to the jaws, so that you could simply take the tarnished wire, place in the jaws, grip lightly and pull it out, giving you clean copper wire again. Also had a small steel rod, old disk drive head guide, that had a similar small sandpaper dick glued on the ends, to clean battery terminals deep in cases, where storage would result in the PVC leaching out, and giving the copper rivets a green film. 3 seconds on each side and away they went, clean and making good contact again.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 16, 2021, 04:32:39 pm
content: Sandpaper is awkward, Scotchbrite works way better. Not the kitchen kind, but the stuff machinists use. I use that whenever I need clean leads for a good connection. Grey for mild tarnish, one of the more aggressive grades for worse.

author: bob91343
author_rank: Super Contributor
timestamp: March 16, 2021, 05:17:25 pm
content: The conductivity is impaired if the corrosion is deep. Otherwise it's not a problem.

author: m3vuv
author_rank: Super Contributor
timestamp: March 16, 2021, 09:27:09 pm
content: if you can get some concentrated hydrochloric acid,add some zinc to it until it stops reacting,then dip the wtre in that before soldering,it works a treat,i make it often,its comonly called spirits of salts here or killed spirits,basicaly strong zinc chloride,for the zinc i normaly use the outer case of cheap dry cell batteys.take the regular saftey measures when working with acid etc blah blah.