Blue Solution After Washing out Rotors with Vinegar ?

[SWG]

I've been been having some troubles with my rotors sticking lately, likely due to a buildup of calcium and I didn't really have the time to send my instrument in to be cleaned. So decided to try washing the valves out with regular white vinegar as I read that this should be ok. I let the valves soak for 15 minutes then dumped out the excess which came out blue. Which freaked me out a bit, and I proceded to neutralize the acid with baking soda and water, and rinsing the whole horn out with fresh water in the shower. Was what I was possibly copper leaching out of the metal or was it just verdigris desolving, since it has been about 2 years since the instrument has been professionally cleaned and if recall correctly I remember seeing a bluish buildup on my valves when I looked at them with a flashlight. Tuba still plays fine, and I will not be doing this again.

Anyone who can help me explain what I saw would be greatly appreciated!

[gocsick]

If only my metallurgy was more useful for tubas more often...

If it was blue it was almost certainly copper chemistry rather than calcium. White vinegar is about 5% acetic acid (CH₃COOH), which will dissolve calcium carbonate scale (CaCO₃ + 2CH₃COOH → Ca(CH₃COO)₂ + H₂O + CO₂↑) but given sufficient time will also attack copper in brass (Cu + 2CH₃COOH → Cu(CH₃COO)₂ + H₂↑).

Over time, copper on valve surfaces oxidizes to cuprous oxide (4Cu + O₂ → 2Cu₂O, reddish) and then to cupric oxide (2Cu₂O + O₂ → 4CuO, black). In the presence of moisture, carbon dioxide, and trace acids from breath, these oxides convert into bluish-green salts such as malachite (2CuO + CO₂ + H₂O → Cu₂(OH)₂CO₃) and azurite (3CuO + 2CO₂ + H₂O → Cu₃(OH)₂(CO₃)₂), or into copper acetates (CuO + 2CH₃COOH → Cu(CH₃COO)₂ + H₂O). This mixture is verdigris, the bluish/green deposits that build up in horns. When you soaked the valves in vinegar, the acetic acid dissolved both the verdigris and some fresh copper to produce soluble copper acetate, which gives the vivid blue color you saw. Neutralizing with baking soda converted any leftover acid into harmless salts (CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂↑), and rinsing thoroughly prevented long-term harm. A short 15-minute soak won’t damage brass or pull copper out of the brass, but long term acidic environment can cause dezincification (red rot) or weaken solder joints.

[bloke]

Without any of that knowledge of physical and chemical properties (as I have none)...

Over on the other side of neutrality, Easy-Off oven cleaner will remove all the nasty chicken grease out of the aluminum lid of an ancient electric fryer (with no apparent harm whatsoever to the lid itself), but - if allowed to soak constantly for a long time an a vat of Easy-Off oven cleaner - that same aluminum fryer lid will completely dissolve.

' an example of knowing a "what" of science, but (though scads of others know it) not the "why".

bloke "suggestions: Don't soak your Bach or Yamaha trumpet aluminum valve stems in oven cleaner overnight. Also, don't put a set of brass saxophone keys - needing their old lacquer stripped - in an aluminum pot and then immerse them in a cauldron of boiling lye water. Yes, the lacquer will strip, but the keys will all be laying in the bottom of the cauldron...How do I know to not do these things?"

[the elephant]

I disagree with all of you.
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I think it was magic.

Carry on, troops.

[gocsick]

Over on the other side of neutrality, Easy-Off oven cleaner will remove all the nasty chicken grease out of the aluminum lid of an ancient electric fryer (with no apparent harm whatsoever to the lid itself), but - if allowed to soak constantly for a long time an a vat of Easy-Off oven cleaner - that same aluminum fryer lid will completely dissolve.

Easy off and aluminum foil is a very easy easy to make quantities of hydrogen gas for filling fire balloons... if you ever want a party trick.

[bloke]

Over on the other side of neutrality, Easy-Off oven cleaner will remove all the nasty chicken grease out of the aluminum lid of an ancient electric fryer (with no apparent harm whatsoever to the lid itself), but - if allowed to soak constantly for a long time an a vat of Easy-Off oven cleaner - that same aluminum fryer lid will completely dissolve.

Easy off and aluminum foil is a very easy easy to make quantities of hydrogen gas for filling fire balloons... if you ever want a party trick.

I probably shouldn't post this, but if you want to create some chaos, wait for garbage collection day, walk down a street where all the big 65 gallon plastic carts are waiting to be dumped into the truck, carry a tube of super glue and some aluminum foil, squirt the super glue on little pieces of foil, and toss one each in each dumpster.

[LibraryMark]

Easy off and aluminum foil is a very easy easy to make quantities of hydrogen gas for filling fire balloons... if you ever want a party trick.

Draino crystals, aluminum foil and water works well, too. It can be a rather violent reaction, so be careful.

[Mary Ann]

Ah, the Tuba Bomb Squad. I love it here.