Removing Black Coating from Copper Wire

[dt4134]

Inspired by the recent threads on shorepower I had a quick check. There's about 2.9V between the Neutral and Earth within the boat (that is at a point where it is easy for me to use the multimeter safely to make the measurements which is actually at the junction box for the input to the shorepower unit, so after the RCD).

Anyway a bit of an inspection shows that some bits of copper wire have a black coating, presumably copper oxide. I've a few bits of spare tinned mains cable that I can use to replace some of the shorter sections, but I don't want to get involved in a major project so I need to clean some of the other bits. Sandpaper is a bit hit and miss on multi-core cable.

So the question is, is there an easy chemical way of removing the copper oxide so I can use a soldering iron to tin the ends of the copper wire?

 

[sailorman]

Inspired by the recent threads on shorepower I had a quick check. There's about 2.9V between the Neutral and Earth within the boat (that is at a point where it is easy for me to use the multimeter safely to make the measurements which is actually at the junction box for the input to the shorepower unit, so after the RCD).

Anyway a bit of an inspection shows that some bits of copper wire have a black coating, presumably copper oxide. I've a few bits of spare tinned mains cable that I can use to replace some of the shorter sections, but I don't want to get involved in a major project so I need to clean some of the other bits. Sandpaper is a bit hit and miss on multi-core cable.

So the question is, is there an easy chemical way of removing the copper oxide so I can use a soldering iron to tin the ends of the copper wire?

the discolouration could be a long way up the cable, that is why tinned cable is recommended for marine use but mow many of us use it

 

[ostell]

The 2.9V is nothing to do with the state of the conductors. Neutral will be grounded at the substation, quite some distance away, and the ground wire taken to ground close to the local distribution box. This leaves a lot of neutral cable to get a voltage drop across, depending on the current flow.

On a positive note you can run your lighting on the 3V!

 

[chewi]

So the question is, is there an easy chemical way of removing the copper oxide so I can use a soldering iron to tin the ends of the copper wire?

yes, but don't ask me what!
20 yrs ago I worked with a chemist and he gave me an eggcupful of a blue chemical that I can use to dunk a corroded wire in. that strips the oxides and allows me to make a connection. Hopefully a chemist will explain what it might be, 'cos I'm running out now!

 

[dt4134]

The 2.9V is nothing to do with the state of the conductors. Neutral will be grounded at the substation, quite some distance away, and the ground wire taken to ground close to the local distribution box. This leaves a lot of neutral cable to get a voltage drop across, depending on the current flow.

On a positive note you can run your lighting on the 3V!

I'm expecting that to be the case, but when I'm on the boat and there's a dry spell I'll set up some way to measure it on the pontoon to confirm it.

 

[lenseman]

. . . . Hopefully a chemist will explain what it might be, . . . . .

Queue VicS?

The only blue things I can think of are Copper Sulphate crystals?

 

[VicS]

Queue VicS?

The only blue things I can think of are Copper Sulphate crystals?

I can think of a few other blue things but nothing that will clean the oxide off copper as far as I know.

The salt and vinegar or citric acid often used would not be advisable as I think that will wick up the wire and give worse trouble in the future.

I used to give a colleague ammonia for cleaning the military buttons he collected but I dont know how he used it!

 

[chewi]

Queue VicS?

The only blue things I can think of are Copper Sulphate crystals?

It's been a liquid for 20yrs. The chemist was an industrial chemist for a PCB fabrication plant, so eating copper was his business. I only left wires in long enough to lose the oxide, then removed & rinsed.

 

[SAMYL]

Try nitric acid if you can get it from your local friendly chemist, thats what they used to use for printed circuits years ago. Or try Cillitbang (or however you spell it).

 

[VicS]

Try nitric acid if you can get it from your local friendly chemist, thats what they used to use for printed circuits years ago. Or try Cillitbang (or however you spell it).

If anything corrosive like nitric acid, or even Cillit Bang, wicks up the cable it could be storing up problems for the future

 

[chewi]

If anything corrosive like nitric acid, or even Cillit Bang, wicks up the cable it could be storing up problems for the future

I'll send it to the head of science at Mrs Chewis's school. He might Id it for us, but won't know till weekend.

 

[Tintin]

Try coka-cola - I am constantly amazed at the things it cleans.

 

[Ruffles]

I just use fine emery paper. Works ok for multi stranded cable.

 

[Bobobolinsky]

It's been a liquid for 20yrs. The chemist was an industrial chemist for a PCB fabrication plant, so eating copper was his business. I only left wires in long enough to lose the oxide, then removed & rinsed.

That would be Ferric III Chloride, but as Vic says anything like that will wick up the wire. Why not just tin the wire ends, dip in number 3 flux and then tin, preferably with a small heated bath

 

[maby]

Many years ago, when I was a young engineer in a machine shop, when we needed to get copper very clean for soldering or brazing, we used to get it quite hot, then drop it into alcohol - always came up lovely and pink!

 

[danielefua]

Many years ago, when I was a young engineer in a machine shop, when we needed to get copper very clean for soldering or brazing, we used to get it quite hot, then drop it into alcohol - always came up lovely and pink!

Very hot + alcohol...
...KABOOOM!!!!

Do you mean that you used to come up lovely and pink????

 

[PCUK]

Plumbers acid flux - From plumbers.

 

[VicS]

Plumbers acid flux - From plumbers.

Dont use anything corrosive which will wick up the cable and cause problems due to corrosion at a later date

 

[maby]

Very hot + alcohol...
...KABOOOM!!!!

Do you mean that you used to come up lovely and pink????

It was a small quantity of alcohol in a jar - and hot, but not red hot... we never had any fires or explosions, but I'm sure the practice is frowned upon these days!

 

[danielefua]

It was a small quantity of alcohol in a jar - and hot, but not red hot... we never had any fires or explosions, but I'm sure the practice is frowned upon these days!

I was kidding, of course! Yes, I do believe you and will try it; if it works it is probably the best alternative to using corrosive liquids.

Daniel