Copper plated steel

[Colinaps]

Afternoon all,

Has anyone any tips for effective renovation of moth-eaten copper plated steel, as in my HRO? Not actually perforated but pitted at the edges.

I was wondering if electrolysis with washing soda would be effective at removing rust without damaging the remaining copper, or would it be feasible to do the same in a copper sulphate solution with a copper anode to replace the plating?

Colin.

[LXSTEIN45]

I can't offer a great deal of help, and not sure how applicable this is, but I used reverse electrolysis to remove rust from a brass plate with good results, and with no harm done to the original surface, so I assume you could do this then reverse the process and re-plate?!
Only thing is, the plate I repaired had only rust deposits from the surrounding iron, but the rust was well adhered, so could not be removed by normal methods. Also bear in mind in your case reverse electrolysis is only good if there is good steel below the rust, otherwise you could end up with large holes and other bits missing!

[LXSTEIN45]

the picture above is quite small, and does not clearly show the rust between charactors, but there was plenty of it that could not be budged! The important point is that the exposed brass remained untouched so I should have thought you would experience similar results with copper?

[Colinaps]

Certainly made a good job - did you use a sacrificial anode?

I'm experimenting on rusty auger bits, bubbling away as I type...

[Colinaps]

or do you mean the brass plate itself was the anode?

[LXSTEIN45]

No I used a base plate from an old hifi stripped of its paint, so I assume it was some sort of fairly straight steel. The rest of the phone was very successfully de-rusted with only minimal pitting left. This included large concretuons and other hardened rust! - I really mean to upload a post of my restoration efforts but I have not yet finished it!

[Radio Wrangler]

If there are any chrome platers near you, copper is a common underlayer so they may already have the process set up. Chrome plating is pricy, but it's the cost of chrome which keeps going up, so if you only want the copper...

David

[ColinTheAmpMan1]

I seem to recall that with some metal substrates, a solution of copper sulphate will deposit a copper plating without recourse to electrickery. The metal base needs to be well-cleaned, though; a trace of grease is disastrous.
Colin.

[Radio Wrangler]

It's called electroless plating. It's done to drilled, raw, PCBs to establish copper down the holes. Then the outsides are given photoresist to define where the tracks are, and the boards are electro-plated up to the intended weight of copper, while the electroplating also builds up hard copper on the cylindrical surfaces of the holes. Then another photoresist process masks off the tracks and holes so the unwanted areas original copper gets etched away.

Electroless copper is a lot weaker than electroplated copper, and it's slower. If you've got something in an electrolyte bath, it's worth dropping a bit of copper in and adding a power supply.

David

[ColinTheAmpMan1]

Originally Posted by Radio Wrangler

It's called electroless plating. It's done to drilled, raw, PCBs to establish copper down the holes.

David, I'm not arguing against what you say about electroless plating, but what I recall isn't the same, I don't think. It requires a metal substrate for the copper to "plate" onto. I think that the process is chemical and related to the chemical activity of both metals. I should remember this from my undergraduate inorganic chemistry lectures, but the years are playing tricks on the memory cells. I can't see how what I am thinking of could be practiced on something non-metallic.

I have a recollection of copper-plating granulated zinc in this fashion. For some reason, this improved the reaction of the zinc with hydrochloric acid for the generation of hydrogen. I suppose that generating hydrogen might be considered a terrorist actitivy these days, but it was pretty innocent when I was at school.....

Regards, Colin.

[emeritus]

I have a 1960's school chemistry book that describes how a steel penknife blade can be plated with copper by dipping it in a copper sulphate solution. Different metals have different "elelctrochemical potentials", and a more positive metal will displace a less positive metal. Those were the days, when schoolboys carried penknives to sharpen their pencils!

When I used to do my own photographic processing, I used the two-bath fixer technique recommended by Amfix, both to ensure that my prints were fixed properly and to get the most out of the fixer. Thus the exhausted fixer was completely saturated with silver, and I found it could be used to silver plate copper and brass by wiping a tissue soaked in exhausted fixer over the surface.