• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Best Way to Clean Stranded Copper Wiring Before Soldering

CJR

NAXJA Forum User
Location
PA
We all know that if surface oxidized STRANDED copper wire is not cleaned right, solder won't stick/coat properly. So, I decided to start this thread to list all the possible ways of prepping older, surface oxidized STRANDED copper wire before soldering. Hopefully the best technique will emerge to help those who want to keep their old XJs running longer. Maybe a sticky will evolve.

We all know that when a solid copper wire gets dirty and/or badly surface oxidized, the procedure is to simply clean and sand the wire before soldering. With stranded copper wire, that approach doesn't work well, unless each strand is tediously separated, sanded, cleaned and soldered. Not a practical or fast approach. So it appears that some type of chemical cleaning is the way to go. Let me start things off by listing some chemical cleaners I'm aware of:

1. A weak Muriatic (HCL) acid solution to dip the stranded wire end in till bright copper appears. Neutralizing acid with a baking soda solution (BSS), cleaning with brake cleaner(BC) or Iso-Propy Alcohol (IPA), soldering.
2. A vinegar + salt solution to dip the wire end in, BSS to neutralize acid , BC or IPA, soldering.
3. Lemon juice + salt solution to dip the wire end in, BSS to neutralize the acid, BC or IPA, soldering.
4. Tri-Sodium Phosphate (TSP) solution to dip wire end in, water rinse, soldering.
5. Phosphoric acid solution to dip wire end in, BSS to neutralize the acid, soldering.
6. Citric acid (readily available for canning) solution to dip wire end in, BSS to neutralize the acid, BC or IPA, soldering.
7. Commercial contact cleaners?

Ok, please add your comments/suggestions/best cleaning experiences so the best cleaning technique for surface oxidized stranded copper wire can evolve.

Best regards,

CJR
 
Sure. Just how will sandpaper effectively clean stranded conductors? That'll work fine for solid, but that's not the point of the thread.

If I have to work on a wire that's oxidised, if I've got enough slack, I'll just trim the end back just past the insulation and re-strip to get clean wire.
 
In most cases a good soldering flux will displace the corrosion and yield a good connection. If it is a very large gauge such as a starter cable, the best thing is to cut it back about an inch to get to clean wire. Never use an acid based flux as the electrical connection will go to crap in short order.
 
In most cases a good soldering flux will displace the corrosion and yield a good connection. If it is a very large gauge such as a starter cable, the best thing is to cut it back about an inch to get to clean wire. Never use an acid based flux as the electrical connection will go to crap in short order.
100% agreed. I find that good rosin core solder (I'm partial to Kester 44RA) and enough heat will displace all but the worst corrosion.

Applying any actual acid solution will make things worse, it will wick back into the wire and behind the insulation and corrosion will fester for years.
 
While acids are effective copper cleaners, I would avoid them, as it is difficult to ensure the acid that wicks up inside the insulated part is washed out and neutralized. I would also stay away from salt, the chlorides are bad.

401 or Fantastic, which is based mostly on a glycol ether EB polar-no-polar solvent mixed with water, that wets and cleans most anything, and has a basic pH is a better choice and can be rinsed off with IPA or DI water.

Ammonia is also a good choice (I think, I have tried it recently... with mixed results).

I have recently found that a SS wire brush works wonders on stranded wire cleanup!!!!!! Followed by a solvent wash that dries fully.
 
Personally, I cut the wire back until good copper is found. It is a sad fact of life that sometimes you just have to replace the wire in order to fix the problem. I could tell you stories...

Try repairing the wiring on a 1948 CJ-2a as an example. Now I remember, I just used the original loom as a build example and made a new harness. It was impossible to repair. And, yes, I used cloth wrapped wire to replicate the original...

That being said, I would never use an acid for the exact reasons given above. The solution will wick up the strands and you will never get it all neutralized.
 
Easiest way to clean stranded copper wire? Replace if corroded. There's no real easy way to clean it reliably, you're better off just scrapping it and starting over.

Anything else is likely to just cause you trouble later on down - if it strips corrosion off of copper, it's going to wick up into the wiring (as mentioned,) and cause you trouble later.
 
I have always used baking soda and water. I let it bubble up like peroxide then scrub with a small wire brush. It has done me well for battery terminals connectors and some wire. Like mentioned by 5-90 if they are that bad replace em.
 
Ecomike,

I seem to recall that ammonia causes inter-granular stress corrosion on copper and brass;i.e. it affects the grain boundaries and slowly eats them away. Likewise, I read that citrus acid does not affect grain boundaries to weaken brass. Also, does 401 or Fantastic dissolve the copper oxide coating or just do a good surface cleaning?

Very interesting comments from all those who responded with their experiences. The comment on best rosin cored solder was interesting. I normqally just buy any rosin core solder for electrical wiring. That may be a big mistake.

Also, comments on just replacing wires was interesting. Replacing single run wires would not be a problem, but replacing wires into connectors and/or connectors becomes another ball of wax. But if that's what has to be done, so be it.

Best regards,

CJR
 
I think how much cleaning is required depends a little on how secure a mechanical and electrical connection you need. I've had good results just spreading the strands out flat and scraping them with a knife. Obviously this doesn't get all sides of every strand, but it gets enough to take solder. I don't think I'd want to do this on a connection that I know is going to need a hundred percent of its current capacity, but if the wire is tightly twisted together and soldered this way, I've found that enough solder hits enough shiny metal to make a nice tight splice, and it's always been adequate. I think with the skimpy wires our Jeeps come with, a good stout solder joint of that sort is probably the least of my worries.

edit to add: I have tried various rosin core solders, which from all appearances were identical in composition, yet some have worked better than others. This may be one of the few things for which I would recommend Radio Shack. For some reason their solder seems to be just a bit more consistently reliable.
 
Ecomike,

I seem to recall that ammonia causes inter-granular stress corrosion on copper and brass;i.e. it affects the grain boundaries and slowly eats them away. Likewise, I read that citrus acid does not affect grain boundaries to weaken brass. Also, does 401 or Fantastic dissolve the copper oxide coating or just do a good surface cleaning?

Very interesting comments from all those who responded with their experiences. The comment on best rosin cored solder was interesting. I normqally just buy any rosin core solder for electrical wiring. That may be a big mistake.

Also, comments on just replacing wires was interesting. Replacing single run wires would not be a problem, but replacing wires into connectors and/or connectors becomes another ball of wax. But if that's what has to be done, so be it.

Best regards,

CJR


There is a difference between NH3 ammonia and ammonium hydroxide. I think household ammonia, is actually ammonium hydroxide sometimes with a surfactant added, a very strong base that cleans the hell out of copper and brass, and was used for decades in metal and electronic plating operations in various formulas for cleaning copper alloys. I don't think a brief 2 minute soak cleaning with ammonia hydroxide would damage the base, core metal, if it is still any good. Ammonium hydroxide will remove the hard oxide scale IIRC, buy dissolving some copper underneath the oxide, thus exposing clean copper. But I prefer the SS wire brush and an IPA rinse best, unless I need to degrease the wire first.

The 401 and Fantastic is just a good ionic and non-ionic cleaner with the cleaning properties of soap, water and a strong hydrocarbon solvent all in one cleaner. I do not think it cleans hard oxide scale, but would remove oil, grease, road salts, and loose oxide corrosion, which should be followed with a clean SS wire brush to remove the remaining hard surface oxide scale, and then rinse with IPA as the final step.
 
This is making me think of getting one of those little wire wheels for my Dremel for cleaning stranded wire. Just have to make sure it's combing the strands instead of trying to ram them back into the insulation :laugh2:
 
Matthew, Ecomike, Kastein,

Excellent comments! I just used to assume that "rosin is rosin", so what's the difference. From comments here, it appears that the solder manufacturers maybe adding something else to the rosin to help breakdown the copper oxides. If that's the case, then the brand of rosin+solder is very important. Good info to know!

Also, an interesting comment on the use of ammonium hydroxide in plating operations. Ammonium hydroxide would then seem to be the better choice over dilute Muriatic acid when cleaning stranded copper wire.

Using a Dremel small wire brush sounds like a very good approach, providing one doesn't get carried away with too much brush pressure on the copper wire.

Also, I agree with the statements that a wire should be replaced if badly corroded. But I've seen cooper wire with a black oxide coating that was not corroded. Getting through/removing that protective oxide coating is the key to a good solder joint.

Hands on experience is worth it's weight in gold!

Best regards,

CJR
 
What you do not want to use is an acid core solder.

The Ammonium hydroxide has the added benefit of neutralizing any acid vapors from the battery that have attacked the copper. But 401, Fantastic, and IPA are mildly basic, will also neutralize any strong acid, but they take way too long to neutralize any remaining weak acid residue.

Sulfuric acid has 2 protons, a weak acid (slow reacting, HSO4-) and a strong acid, fast reacting, H-HSO4 (H2SO4). You need to kill both, and a string base will do that, ie. Ammonium Hydroxide, NH4OH.

Sodium Bi-carbonate is a both a weak acid and a weak base at the same time!!! A great Hazmat neutralizer for acid or caustic spills!!!!
 
Sodium Bicarbonate = Arm & Hammer Baking Soda.....
I generally add this with a little deionized water to the corrosion build up on the battery terminals or when there is a acid spill.
Great stuff.....
 
Sodium Bicarbonate = Arm & Hammer Baking Soda.....
I generally add this with a little deionized water to the corrosion build up on the battery terminals or when there is a acid spill.
Great stuff.....

If the acid is lead sulfate/sulfuric acid from a battery, the NaHCO3 ( A&H Baking soda) is great for immobilizing the highly water soluble lead ions as a water insoluble lead carbonate.
 
The responses so far have prompted me to do further technical reading. Here's what I found;
1. Ammonium hydroxide does an excellent cleaning of copper. Unfortunately it prevents passivation of the copper,i.e. the formation of a protective oxide layer on the copper wire next to the soldered joint. That means that the copper wire in the soldered joint will be protected from corrosion by the solder, but the un-passivated copper wire next to the soldered joint will corrode.
2. Hydrogen peroxide is also used to clean copper in the printed circuit industry. A big benefit is that after the hydrogen peroxide cleans the copper it promotes passivation which protects the copper against corrosion. Some additional benefits are no chlorides and safe residuals of Hydrogen and Oxygen. Anyone ever try hydrogen peroxide (H2O2) to clean copper stranded wire and have comments?
3. Kester 44 Rosin Core appears to be THE premier rosin solder and better than Radio Shack rosin solders. I'm beginning to realize that my past soldering problems resulted from my using garbage rosin solders. Lesson learned!

Best regards,

CJR
 
Sodium Bicarbonate = Arm & Hammer Baking Soda.....
I generally add this with a little deionized water to the corrosion build up on the battery terminals or when there is a acid spill.
Great stuff.....
Also Window cleaner will neutralize battery acid too. I used to know what was in it that did the trick, but I haven't had to maintain industrial batteries for several years now, and just can't remember.
 
The responses so far have prompted me to do further technical reading. Here's what I found;
1. Ammonium hydroxide does an excellent cleaning of copper. Unfortunately it prevents passivation of the copper,i.e. the formation of a protective oxide layer on the copper wire next to the soldered joint. That means that the copper wire in the soldered joint will be protected from corrosion by the solder, but the un-passivated copper wire next to the soldered joint will corrode.
2. Hydrogen peroxide is also used to clean copper in the printed circuit industry. A big benefit is that after the hydrogen peroxide cleans the copper it promotes passivation which protects the copper against corrosion. Some additional benefits are no chlorides and safe residuals of Hydrogen and Oxygen. Anyone ever try hydrogen peroxide (H2O2) to clean copper stranded wire and have comments?
3. Kester 44 Rosin Core appears to be THE premier rosin solder and better than Radio Shack rosin solders. I'm beginning to realize that my past soldering problems resulted from my using garbage rosin solders. Lesson learned!

Best regards,

CJR

Hydrogen peroxide is also a great choice, YES!!! BUT use only the low concentration, 0.5% OTC grade, and do not put the wire connection in the HP bottle, use just a little in a small cup, and then do NOT save it back in the main bottle. Just a few ions of copper will catalytically decompose the entire bottle of HP if they get into the main bottle!!! Do not use industrial strength HP!!!!

I think ammonium hydroxide first followed by H2O2 would be a great combo, then a DI water rinse, followed by IPA alcohol!!!!! But I would degrease the wires of any oil or DE grease first with a fast dry brake cleaner, that does not leave any residue. The Red can CRC stuff that use to dry completely, not longer dries completely, they changed the formula recently!!!!
 
Last edited:
Back
Top