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  for Metal Finishing since 1989
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Dissolving Copper Not Nickel

I would like a material that will dissolve a copper coating on electroformed nickel. Is there a commercial solvent that will dissolve the copper but not affect the electrode formed nickel at all? The context for this question is a process that uses copper as a release layer for a nickel cylinder that is electroformed from a mandrel.

Paul Gorenstein
- Cambridge, Massachusetts

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First of two simultaneous responses --

My Metal Finishing Guidebook says you can use a solution of 90 g/L NaCN and 15 g/L NaOH, room temperature, 6 V, work is anodic, and use a steel cathode. You need to reactivate the nickel in HCl prior to replating.

James Totter, CEF
- Tallahassee, Florida
 

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Second of two simultaneous responses --  

I've got some recipes for you:

A commercial stripper is "Enstrip C", 100 g/l , temperature 21-29 C . You can buy it by Enthone Inc.

Other "home-brew" strippers are: Sodium sulfide:230 g/l,sulfur 16 g/l.Boil to dissolve sulfur. Use at room temperature.Brush off loose sulfide.Rinse and dip in 10% sodium cyanide solution.Repeat several times.

Or: Sodium sulfide:100-200 g/l. Use at room temperature.

Or: Mix 1 liter ammonium hydroxide (25%) with 0.1 liter hydrogen- peroxide and 1 liter water.Use at room temperature.

Kind regards,

Sjamp van Esch
- Eindhoven, The Netherlands