I caution you to wait until you've seen what more qualified folks will say, but I'll tell you what I did last year that worked VERY well for me. Follow my example at your own risk.Henry wrote: Is there some cleaning chemical which, used with discretion and thoroughly rinsed (ie: lime away) which might have a salutory effect? Will I be blacklisted by NABIRT for even asking the latter? All help is deeply appreciated- thanks- Henry
I found a trash can large enough to hold the entire body of my horn. I put this trash can in the bathtub, placed my tuba (minus valves and slides) in a heavy-duty trash bag, and placed tuba and trashbag combined down in the can. I poured 50/50 water and white vinegar (3 gallons of each) into the bell, most of which wound its way through and came out into the bag. Then, holding the top of the bag up, I filled the can with water. The water in the can equalized the pressure, pushing the vinegar and water solution in the bag up to fill all the valve tubing (I didn't have any loops that would trap air in my horn).
As the can filled, the horn began to float, so I added another gallon or so of the vinegar/water solution to keep it up with the water-line in the can.
I let that sit for about 3 hours, then dumped the water and washed with soap and water as I normally would.
Again, your mileage may vary, your horn may dissolve, your trashcan may fall over and crack the tub and dent the tuba -- if you do it, YOU take the risk. But it worked very well for me, costing me a total of about $10 in gallon jugs of vinegar.
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Joe Baker, who is a cheapskate!!