Rust in flash copper solution

[jlmccuan]

After several unsuccessful attempts at flash copper on a cast iron part, I inadvertantly left the part submerged. Now it looks as though rust has formed and my solution is brown instead of blue. Do I have to throw it out and start over? I have filtered thru coffee filters, but the brown remains. Suggestions??

[jimcarry]

Re: Rust in flash copper solution

The growing concern for worker safety and the government regulations on cyanide have made the use of non-cyanide copper desirable. However, they cannot yet replace cyanide processes in all applications, especially for barrel plating zinc die castings due to the formation of a non-adhering immersion copper deposit.
Many non-cyanide copper processes operate between the same plating properties as cyanide-copper baths. A proprietary non-hazardous, easier-to-waste-treat complex replaces cyanide. A typical bath formulation requires 11 g/liter of copper metal at a pH of around 9.0. Cyanide copper solutions have a pH of at least 11.
Non-cyanide processes operate between 130 and 150F, with air agitation. Use an anode-to-cathode ratio of 2:1 and the same anodes used in cyanide solutions.
Analysis and routine additions of the complex are all that are typically needed to maintain the bath. However, the removal of metallic impurities might be a major problem. Due to deficiencies within many non-cyanide copper processes, they should only be used after extensive testing on the actual parts to be plated produced under production conditions.

[dadkar2]

Re: Rust in flash copper solution

If the solution is brown my suggestion would be to replace it.

Ken