It’s either a mild acid, or it’s whatever solution is used for ultrasound type of percussive cleaning.
In the past, ultrasound cleaners used some pretty effective stuff, which consisted of compounds including freon and trichloroethane. “Green” reg’s have required that they retreat to aqueous-based types of solutions.
The mild acid solution is far less expensive and - in my opinion - far more effective and safer for brass that features some rotting areas, but everyone has their opinions.
Obviously, if someone spends $15,000-$20,000 on some tuba-accommodating ultrasound rig, they’re going to not only champion that method, but likely also feel a great need to sell cleaning jobs.
When I stick my bare hand down in my acid solution to fish out a part which drifted out of the parts basket, the only place on my skin that might sting just a little bit is where I might have a cut or scrape, and I feel like I’ve got plenty of time to neutralize that acid on the surface of my skin. Yes, I could go get the rubber gloves, but it’s harder to find a stray piece - in the bottom of the huge tub - with gloves on.
The mild acid lasts and lasts, but does pick up a little copper in the solution over time. It can be mostly leached out by leaving a chunk of steel in the solution for a while. Otherwise, an older non-copper-leached acid solution can leave a very light coating of copper on non-lacquered surfaces - a coating which can be removed from slide tube surfaces, etc. with very light polishing… and – with school instruments that haven’t been treated particularly nicely (and when working with limited school repair budgets) – I just leave that negligible copper – when it occurs – in place.
The mild acid seems is easy on silver plated surfaces, and only very subtly might leave copper residue on silver, and only if left in the solution way too long.
With the strength that are generally mix my solution – by how much water dilutes it – I usually keep instruments in there for about ten minutes, but might put a few heavily-limed slides, rotors, or whatever back in after everything else has been taken out, and might even leave them in there for twenty more minutes. After that, I sort of give up and go ahead and chip off the remaining lime.
Obviously, chemical needs to be drained and rinsed off with a generous amount of water.
I have a huge old enamel elevated bathtub for rinsing, but - if it’s not inclement - it’s often easier for me to set a tuba body outside on soft grass and completely rinse it inside and out with a garden hose connected to a pasture hydrant.
Approximately three days after I took possession of that huge tuba I’ve been posting about, I did this big cleaning job, because it needed it, and not just because I thought “it might be a good idea”. Big tubas with a lot of parts – and with parts that fit with extraordinary precision - take more time than just about anything to clean…and not to mention that - when they are handmade - they are very thin and very easy to dent. It required hours to clean and reassemble that particular instrument, and – rather than maybe $80 - $100 bucks to clean a little 3/4 size 3-valve tuba – I would’ve charged someone else hundreds of dollars to do what I did for my own instrument.
That’s all I know, but if you ask me questions for which I do not know the answers, I’ll be glad to make up crap.
