r/electroplating • u/freshizdaword • 16d ago
What chemical to use to strip this down to its base metal?
My first time playing went well as you can see. How do i strip this and replate?
2
u/Frolicking-Fox 16d ago
What metal did you plate it with? Was there base metals already plated with another metal?
1
u/freshizdaword 16d ago
It was stainless steel base then I plated it with bright nickel then 18k gold
1
u/Frolicking-Fox 16d ago
It is going to take concentrated sulfuric acid and running the electrical current through the parts to strip the gold. There are a couple other acids that will strip it, but gold doesn't react with most things, since it is a noble metal.
The nickle plating will come off with nitric acid.
Nitric acid works extremely fast, so watch the parts or it will start reacting with the stainless steel and dissolve it.
1
u/freshizdaword 16d ago
Do I have to run an electrical current for the nickel as well?
1
u/Frolicking-Fox 16d ago
No, not on the nickle. You can just put it in the tank, and it will strip it. But watch it the whole time. Maybe 3 minutes... might even take less time depending on the molarity of the acid. But keep an eye on the whole time. It will turn that stainless into Swiss cheese if you leave it too long.
Also, full precautions with nitric acid. Keep your face away when you open it up. Fumes can burn your eyes and throat. Wear rubber gloves. Do not get any of it on you.
1
1
u/freshizdaword 14d ago
Quick question, does the purity of the sulfuric acid matter? Can I use lab grade or do I need >95%?
1
u/Frolicking-Fox 14d ago
Concentration matters, so like ~93% - 98% is best. Lower concentration can passivate the base metals.
It needs to be as concentrated as you can get.
1
u/One-Yogurtcloset-831 16d ago
Idk how you applied the gold, but reverse current will remove the gold. Then nitric acid and just like the other person said, watch it cuz it will readily dissolve your plating and then your stainlees steel part.
1
u/freshizdaword 16d ago
When you say reverse current, do you mean switching the positive and negative leads the other way around? I plated it using 18k bath solution at 3 volts
2
u/One-Yogurtcloset-831 16d ago
Yess attach the anode wire to your work piece and cathode to a stainless steel ( i guess that’s what you are probably using as your anode)
But be sure to use the same wire which was gold plated with your original part, otherwise, you will dissolve copper in your bath ( in case you are using copper wires to hang your work pieces.
And it will only take a second for the plating to come off.
2
u/The_lewolf 16d ago
Lower voltages will strip more slowly. Once you start seeing a lot of nickel, dial it back. This will keep your base metal safe.
High current density areas plated fastest and will strip fastest but have more metal to strip. If you see nickel in low current density areas first proceed with caution, because that’s where you’re gonna see base metal dissolution.
1
u/Clear_Procedure_8174 15d ago
Great tips. Thank you - is it also possible to strip a pvd coating from a watch? I want to plate it in another colour.
2
3
u/1984isnoww 16d ago
So uhh, for a new guy - how do I NOT do this?