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Corrosion Resistance via Humidity Test

Which has the higher corrosion resistance under nickel, cyanide, copper or acid copper and why? Is acid copper easier to buff (flow ) than cyanide?

Don Marsh
Retired - Abington, Pennsylvania
2001

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It all depends on the substrate the copper and nickel is going on to. In general, however, cyanide copper is a better layer as it is more adherent than the acid copper. If adhesion is required, non ferrous alloys, brass, bronze and nickel silver can all be plated with acid copper, but ferrous substrates and zinc cannot. Acid copper has better leveling properties and can be plated at higher rates. Conversely, cyanide copper has better throwing power. Obviously, cyanide copper has much greater effluent treatment problems.

Hope this answers your question.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2001

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As far as the answer goes in relation to corrosion resistance there are a number of answers. If there is no porosity there would be no difference but in the case of say porous diecastings bright acid copper has been shown to give improvement because of the ability to micro throw and level out these imperfections which otherwise would be a site for corrosion. As far as polishing copper, acid is generally better but it depends on the concentration of the additive system, higher concentrations will lead to harder deposits.

Geoffrey Whitelaw
- Port Melbourne, Australia
2001

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