[Jamesbeat]

I collect vintage razors, which for the most part are made of nickel plated brass.

Over the years, the nickel plate gets worn away in places, and by the time I get my hands on them, the razors look very shabby.

For years, I've been stripping the remaining plating from these worn razors polishing the brass to make them look nice again (albeit gold instead of silver in color).
The way I've been doing this is making the razor the anode in an electrolysis bath. I use stainless steel (wire, spoon etc) as the cathode and for the electrolyte, a simple brine of sodium chloride.
I usually use quite high (for electrolysis) voltages in the order of 5-12v.

I initially tried this setup because I couldn't find a readily available and inexpensive source of any nickel salts, and was surprised to find that it works very well indeed.
The plating strips very quickly, about three to five minutes, and then the razor can be cleaned off with a wire brush ready for ploishing.

Thing is though, I'm curious as to what the gunk that's left in the electrolyte solution is.
It seems to be an insoluble precipitate, and is green in color.

I'm assuming the green indicates nickel and copper (from the brass) compounds, but I'd like to know what compound(s) it/they are likely to be?

Other than idle curiosity, I also want to know what it is so that I can dispose of it properly.
I've done this quite a few times, but I have never poured my used electrolyte down the drain, because I know that nickel compunds should be disposed of properly.
At the moment, I have a five gallon plastic paint container (airtight lid) about 1/4 full of the stuff sitting in my garage.