red-rot from demon soda

[MikeW]

In a recent thread, it was mentioned that the "lime" that appears in tubas is associated with de-zincification, or red-rot.

It was also pointed out that lime doesn't appear if the instrument is not played, so we must blowing something in there to cause it.

Given that breath contains water vapor and carbon dioxide, and that these two can combine to form carbonic acid, I wondered if there could be a reaction in which the carbonic acid combined with the zinc, to form the "lime" (which would thus actually be zinc carbonate, or something derived from it). It may also combine more slowly with the copper, which would explain the green tinge in the lime.

Here is a link that could support this view, although its author mentions that acid from soda is an important factor, plus possibly acids from other food sources; soda (beverage) contains ready-made carbonic acid, which would probably enhance the impact of normal breathing.

http://www.brassarts.com/about_red_rot.htm

[Ben]

not to mention any sugars you blow in your horn can be "fermented" into acetic acid, or other small molecules that can be acidic. Your theory is pretty sound.

[jeopardymaster]

Whenever I see dezinctification occurring in a brass instrument, inside an instrument at the very same spot (nearly always) is an attached blob of lime. Lime is not acidic; it is alkaline.

I believe it. "Lime" is calcium carbonate, calcium hydroxide, calcium oxide, calcium phosphate, any or all of the above, or some other combination containing calcium. The plaque that builds up on human teeth - and turns to tartar or calculus if we don't brush often and well enough - also contains calcium. Not exactly a QED, but maybe - just maybe - it might be a good idea, before you pick up your horn, to BRUSH YOUR TEETH.

[iiipopes]

That's the whole point: the zinc is alkaline, and is being leeched out of the brass by something acidic, whether carbonic acid, acetic acid, etc.

Yes, you use a mild acid to dissolve the lime deposits and other junk, and I know you also rinse afterwards to neutralize the acid. It's the acid that is not rinsed out, or worse yet, held against the brass by other gunk, that is one cause of the red rot.

[iiipopes]

OK, maybe it's the kind of acid -- like, you know, you store hydrocloric acid in glass because it eats everything else, and you store hydrofluoric acid in plastic because it eats glass...

Then again, I may have misread your post. Never mind. Time for the second cup of coffee.

[Ben]

"lime"

I think we are assuming much when we say lime. The exact composition of the deposit would be an interesting topic in and of itself. Zinc(metal) reacts readily in acidic environments as a reducing agent - its great at doing that, and I have utilized if often for that purpose in my day job. The "ecosystem" inside of a horn is most likely very complex. There are most likely microbes that could very readily generate acids, there are plenty of food sources depending on the hygiene of the musician. What has not been discussed is the counter ion associated with the zinc - what is the salt? This is important because different salt counter ions affect the salt's solubilities. Flux usually contains a sulfate acid, when combined with zinc, these salts are not soluble, and do not wash away well. Zinc chloride, acetate, carbonate, or other salts all have differing solubility, and may leach our of the horn differently. I am not a metallurgist, or even an inorganic chemist. But these are my thoughts as an organic chemist.

[MikeW]

[quote="bloke"' (alkaline lime deposits which sit directly below dezinctified places on brass instruments - thus indicating a pretty darn strong cause/effect relationship)[/quote]

A correlation that strong is certainly grounds for suspecting causality (but not proof:-"Correlation does not imply Causality"), but there is also the question of horse v. cart relativity:

did the "lime" cause the red-rot ?
did the red-rot create the "lime" ?

If the "lime" is something carried into the tuba by the player's breath, why would it collect at the site of the red rot ? To me, it seems more likely that the "lime" was created in situ by the red rot (when dezincification occurs in domestic water systems, the white stuff blocking the pipes is zinc oxide).

[iiipopes]

Did MikeW actually post on tubenet, or did I merely inhale too much THC ?

Read 'em & weep.

[MikeW]

existentialist/cart-horse/186/24AW/Bazooka Joe

Did MikeW actually post on tubenet, or did I merely inhale too much THC ?

If that's an actual quote from something you believe you've seen on-screen recently, then what can I say... maybe "quit hogging the bong" ?

[MikeW]

If you Google dezincification, you'll get several days worth of reading material.

Here's one that should have a special appeal for Bloke...

http://www.buildingscience.com/document ... cification

She's even wearing the right color dress.

[MikeW]

Apart from the socio/political significance, that article also mentions that water pipes with scaling by calcium and magnesium salts (aka lime) are protected from dezincification.

On the other hand, I have yet to find a solid account of what causes dezincification. Wikipedia mentions "microscopic scale galvanic corrosion", several articles mention carbon dioxide (breath ?) and the presence of chloride and sulphate ions (spit ?); all the descriptions mention water (condensation ?) - especially stagnant water, like the film of condensation inside a tuba. Some people also suggest a role for ammonia (stretching a bit, but could it be produced by bacteria ?).

Whatever the mechanism is, we seem to provide the ideal environment for it.

Besides, who wants a cell phone that shouts "bong' ?

[MikeW]

carbon-something-or-other causes man-made tubal warming.

Politics ? Ok, stop already!

[MikeW]

Mr. Dobalina ?

It's on U-tube, but I never heard it before: Interesting rhythm, but the poetry seems to lack coherence (but then so does the Ring when you don't speak German) - or does the dark lord reveal himself when I play it backwards ?

Was this the flip side of something, or did their minders actually let them do this in public ?

[MikeW]

Obviously I could have been clearer, but I was trying to be polite.

My apologies, I forgot where I was (am ?), I'll try not to let it happen again.

In plain English: you got it bass-ackards, the crud on the inside is what is left of the zinc. It didn't cause the red-rot, it was made by the red-rot - result, NOT cause.

Of course, it would help if someone had real evidence, one way or the other.

And I preferred the original; the remix with the electronic jew's harp did nothing for me.

[MikeW]

Pokerface.

[Ken Herrick]

In recognition of Bloke's 26,000th post, I'll chuck a spanner in the works here.

Many moons ago, when I worked for a famous maker of soprano tubas, we would, all to often have to scrap and replace parts of NEW instruments!
Often those luverly little red spots would show up during the polishing stage. WORSE would be when they showed up after plating.

Conclusion?

A lot of "red rot" is actually imperfections in the brass which are present from day one.

(Do I win a prize for being first to acknowledge Bloke's milestone?)