Summary for polish copper Discussion
How to polish copper is the core question, and the thread suggests that the old nitric-acid/chromic-acid dip is not the preferred answer for achieving a bright finish. The original poster described polishing copper bus bars by dipping them in 15-20% nitric acid, then passivating with chromic acid and rinsing, and asked for a better method for high brightness. Ted Mooney, P.E. did not give a full polishing recipe in the excerpt, but later answered a related question about tarnish prevention by saying sodium benzotriazole is more effective than citric acid for copper. The poster also asked how to isolate only the contact sites on polished bars so those areas could be plated with tin or silver and the rest later de-isolated, but no solution is shown in the excerpt. Overall, the discussion points to better tarnish control rather than endorsing the older acid-dip approach.
Q. What is the best method for polishing copper?
Abdo Akila
plating shop employee – Cairo, Egypt
December 28, 2008
? Hi, Abdo. I think people wanr to help you, but your question is too vague; we don’t know if you are talking about one part or millions, pinhead size or a skyscraper, etc. Please tell us the details of your situation. Thanks!
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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December 29, 2008
Q. My company work on electrical control panel using copper bars as conductors with dimensions (10 cm*10 mm*3 m), (12 cm*12 mm*3 m),(20 mm*5 mm*2 m) and like this.
My current method to copper polishing and treatment is dipping in nitric acid 15-20% till 5 minute then passivated with chromic acid (rinse stage with chrome) then rinse with current water
I know that this very old method
Copper is very sensitive metal so we want to know the best method for polishing copper with high brightness.
Abdo Akila [returning]
plating shop employee – Cairo, Egypt
December 31, 2008
A. Two suggestions to look into: use sulfuric acid plus hydrogen peroxide for the brightening instead of nitric acid; use benzotriazole
⇦ on
or
Amazon [affil link]
as the tarnish preventer instead of chromic acid. I can’t promise that both or either of these will be an improvement, but they are more modern and are worth looking into. Good luck!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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January 7, 2009
Q. I am very thankful to you.
I have another question:
After polishing copper bars there are some contact sites along the bar, i.e., if I have bar of length 2 m and this bar has 4 contact sites which used to contact the bar with other bars, how can I isolate this bar except at the contact site to plate this site by tin or silver (cost reduction), then after plating remove this isolation?
Abdo Akila [returning]
plating shop employee – Cairo, Egypt
January 17, 2009
A. Hi. If it’s just the ends, you can dip the pieces vertically, just enough to plate the ends (you may want a strip of platers tape or resist beyond the point you want to plate for a clean edge/boundary.) If you need to plate a spot in the middle, your only choices may be to either brush plate instead of tank plate, or to mask/tape everything else. But in masking/taping ‘everything else’, it might be possible to have a reusable PVC sleeve that you can place over most of the bar and just tape the ends of the sleeve.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Q. I think that citric acid
⇦ on
or
Amazon [affil link] is the best on of tarnish preventer. What is your opinion?
Monto Carlo
Plating shop employee – Cairo, Egypt
January 14, 2009
A. Hi Monto. I’m sure that sodium benzotriazole is a more effective tarnish preventer for copper.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
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