Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

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The polish of copper wire fades in two days

Q. We manufacture earth copper wires of different gauges. Presently we are using nitric acid for polishing. the polishing lasts for 1 or 2 days. Is there any method in which polishing lasts at least for 10 days?

MATHAN ANNAMALAICHAMY
SUPERVISER - MADURAI, TAMILNADU, India
2003

A. Hi Mathan. You probably need a corrosion inhibitor. Tuck the parts away with VCI, or dip them in benzotriazole ⇦ this on eBay or Amazon [affil links] , or try a chromate conversion coating. Best of luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

A. Hi There,

I understand the problem, I overcome this by dipping the copper conductors a degreaser followed by a weak hydrochloric (2%) acid solution, rinsing of in Cold (less than 25 °C distilled - deionized water) and then dipping the wire in a product that produces a thin tin plating - electroless method. Of course followed by another water rinse... The resulting plating is highly solderable even after months.

Good Luck

Robert Fyfe
Audio Eng. - Wyoming, NSW, Australia
2004

A. I am not sure why, but if you chemically polish with hydrogen peroxide/acid on brass you get remarkably long life before tarnishing. I believe the same would apply for copper. One thing though is critical. The final rinse must not be at all acid, i.e., pH greater than 8. If at all acid, fast tarnishing occurs, and I am sure this would also for brightening in nitric.

Geoffrey Whitelaw
- Port Melbourne, Australia
2003

Q. Geoff from Australia mentions a hydrogen peroxide/acid solution for copper. What is the acid?

Stan P Burnett
Hobby - Granbury, Texas
2004

A. If you wish to go this way you need a proprietary stabilized hydrogen peroxide. For copper 30% vol Stabilized Peroxide 1-2% sulfuric acid For brass I prefer 3% nitric acid.

Geoffrey Whitelaw
- Port Melbourne, Australia
2004

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