The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Deplating copper

I'm looking for a way to "de-plate" copper from a stainless steel cathode roller. Any help out there?

John Wall
- Marlborough, New Hampshire
2001

---

2001

Copper is readily attacked by alkalies; hence, a hot sodium or potassium hydroxide solution will remove the copper quite easily, especially in conjuction with ultrasonics. The high pH will have little or no effect on most stainless.

Waste disposal: The copper hydroxide will be the bluish sediment in the stripping solution after the reaction is over. As long as the pH is high, the stripping solution should will not have a lot of residual copper. After the copper hydroxide settles out, decant the clear liquid off of the sediment--if the copper concentration is low enough, you can dilute it and dispose of the liquid. You can either dry the remains and properly dispose of the copper hydroxide (toxic), or you can treat the remaining precipitate as is; the copper hydroxide will dissolve in acids--you can adjust the pH of the remaining (solution + precipitate) with HCl to make copper nitrate. Then, you adjust the pH back to neutral with baking soda [in bulk on eBay or Amazon [affil links] or whatever you have lying around. The Copper nitrate can be disposed of via your normal hazmat provider. You can go one step further & roast it in air at 250C or so to make copper oxide, but that is just more mess and hazmat to worry about.

Was this too much info?

Dale Woika
- Bellefonte, PA, US

---

Nitric acid would remove the copper a lot faster and at room temp. Down side being nitrous oxides you need a fume cupboard or extraction.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England
2001

---

John -

Another way of stripping the copper is to use a peroxide/sulfuric acid blend. The solution runs at just above room temp and doesn't generate the fumes of some other methods. It also creates copper sulphate ⇦ this on eBay or Amazon [affil links] as a precipitate and the peroxide is easy to waste treat.

Dan Brewer
chemical process supplier - Gurnee, Illinois
2001

SOME PEOPLE ON THIS SITE POSTED THAT YOU CAN USE SODIUM HYDROXIDE OR POTASSIUM HYDROXIDE IN A SOLUTION TO REMOVE COPPER FROM STEEL. CAN ANYONE TELL ME HOW MANY POUNDS OF FLAKES OR PEARLS IT WOULD TAKE TO MAKE UP ABOUT 3 GALLONS OF THE SOLUTION. THANKS BILL

BILL SNYDER
HOBBYIST PLATER - PENSACOLA, Florida, USA
2007