Flaky tuning slide plating

[nfl04]

Hello!
I am currently in need of some help with a tuba I acquired near Christmas last year. It’s a 1974 3-valve rotary Eb, made in Kiev during the reign of the Soviet Union. It didn’t cost much, but oh boy, is it a fixer-upper. It’s had so many issues that I am just now managing to take care of despite having worked on them since the week it came in from Ukraine. Despite that, it seems to be a very solid tuba and a good player, of which I’m amazed by now that I’ve been able to get into the nitty-gritty inside of it and discovered the insides to be completely white with dry, crusty, solidified calcium and salt buildup. As I’ve been taking care of this major cleaning issue, another one has only started to get worse. When this tuba was built, all of the tuning slides were nickel-plated. Now, that plating is extremely flaky, and has already came off in chunks. This causes the slides to get super dirty, and they don’t slide smoothly like they should. And of course, whenever I move them I can just hear the flakes of plating come off and scratching the inside tubing. Which, is obviously a major problem. Having said that, here’s where I need the help. How in the world can I get the nickel plating off the slides? I just gave the slides a vinegar bath for about a week to get the calcium/salt buildup out, and it seemed to do an un-intended decent job of getting under the flaky plating, and getting it to detach from the raw brass and peel off either while still in the vinegar or while I washed them out with soapy water earlier. So, are there any sure-fire ways to strip the tuning slides of the interior nickel plating?

Thanks for the help guys!

[nfl04]

If you are saying that the inner slides (the 'legs' that are attached to the u shaped crook) have nickel peeling off them, um...

Once the nickel is all off, won't the inners have a fairly loose fit into the outers? I don't know how thick the nickel plating is/was, but multiplied by two (both walls of a tube) won't that cause some air leakage?

Or maybe I'm misunderstanding you.

No, you are understood correctly. The inner tubing on the slides is nickel plated and it’s peeling off. A large majority is already off, so I just want to get the rest that flakes off tiny patches off so I don’t have to worry about patches peeling off inside the instrument anymore. And that is a good point, it could cause air leakage; it’s a major possibility. However, I haven’t detected any air leakage from them yet and there’s a large amount of plating already gone. Plus, they fit so tightly it’s hard to move them when they’re in the tuba, and the flaky plating certainly doesn’t help with the friction. The plating is super thin though, so I don’t think it will be a major difference. But hey, I could always be very wrong.


Edit: I can take some pictures for reference, I’ll be taking them out of the second bath today that I do to neutralize any vinegar residue so it doesn’t end up with orange goop on it