Lead contamination of nickel bath?

[hakelly]

I want to electroless nickel plate a brass tube on an old outboard. It has a smaller tube soldered alongside with a considerable fillet of solder in between. I believe it was originally nickel plated.
Will the lead harm the plating bath? If so, is there a workaround?

[dadkar2]

Hello HAKelly,

I have plated nickel DIRECTLY over lead solder many times with good success. However, when I am doing repair work and I need to use lead as a filler, I ALWAYS use copper over it. This is because the copper will fill the remaining "dimple" created by sanding down to level, and will fill much faster than any other plating method. It smooths it over as a prep for nickel. It's also the preferred approach if you are plating nickel over a solid lead part. Caswell's Flash copper is great for this. Be aware that the pickling process (even with Pickle 4) can potentially blacken the lead and could give you plating problems. So either use a dilute pickle (eg 2 oz Pickle 4 salt per gallon distilled water), or avoid it.

As far as bath contamination is concerned, you'll be fine as long as you don't let a part sit in the plating solution un-powered for any length of time (more than a minute or so). And for goodness sakes don't reverse the polarity. ALWAYS apply positive to the anodes. I mention this because I know some folks like to reverse plate briefly to improve adhesion. I've found this to be hazardous to the health of the nickel plating bath. Use a separate electrocleaning bath if you use this approach.

One last thought. If you are soldering something and then plating it, make absolutely triple sure that every possible trace of flux is removed. When it is visibly gone, clean it again in a fresh cleaning bath at elevated temperature (don't heat up volatile solvents!). Fluxes can kill adhesion of plating.

Ken

[hakelly]

Thanks Ken. That's good advice. I figured there was a way since it was done originally.
I was thinking about the electroless method, but I could go either way, since it seems like your reply refers to the electrode method. I have done some gun barrel bluing in the past so have the necessary tanks, heaters, cleaning chemicals.
Howard