DIY Cryogenics?

[bort]

The actual low temperature in Minneapolis is supposed to be -24F tonight. Leave the tuba outside for some free cryogenic treatment?

[bisontuba]

[Ken Herrick]

If you think there are stresses caused by joints not being aligned correctly when soldered, I could fix that by stting the tuba out in the sun for a few hours. The solder would soften just enough to let things pop into their proper place.
Oz weather the opposite to yours.

[iiipopes]

At a place I used to work fifteen years ago, at one point we got new desk chair mats to preserve the newly laid carpet. They came rolled up, and were not amenable to flattening out. So...bearing the brunt of all the jokes about setting up my office outside, the next morning after I got to work, it was a sunny day. So I took my mat outside to the south side of the building, laid it out on the concrete, and waited until after lunch. The heat of the sun made it pliable, and I took it back in, placed it in the proper position under the edge of my desk, and got back to work while everybody else was still fighting their mats.

[Big Francis]

I left my horn in my truck over the weekend too. Pulling it out tonight to practice. I'll let you know if I notice a difference

[MaryAnn]

Well, I"m not sure how it was done, but when I got my horn, I was told it had been "cryogenetically treated." Not sure what that means, but it seems complicated.

[PaulMaybery]

There is an issue with letting a horn get too cold. The different metals, that is solder and brass, expand and contract at different rates and also in different amounts. Especially here in the artic cold of the upper mid-west it is not really prudent to leave a tuba to get to 25 below zero. Especially over and over, the continued freeze/thaw can eventually crack a joint loose. Yes, I've had it happen. It's not the end of the world, but it is inconvenient. Also with condensation in a horn from the warm air after a gig, I can see valve casings getting slightly expanded from the ice. What was once a nice 1 or 2 thousanths tolerance could be openend significantly and effect compression. (Afterall, ice is used to crack granite for builing purposes. It is very powerful.) I suppose on older and worn valves this is not so much an issue, but on new tight fitting pistons they could easily be compromised. You may empty the tuba when you put it in the case, but there is still significant moister in the air inside that has yet to condense, and it will, particularly when the temp drops. Just sayin' ...

[Donn]

Also with condensation in a horn from the warm air after a gig, I can see valve casings getting slightly expanded from the ice. What was once a nice 1 or 2 thousanths tolerance could be openend significantly and effect compression.

a brief selection of the comments when this came up this last winter -
- pistons are usually not as strong, against side forces, as brass valve casings (and they're stronger in some places than others), so we'd expect to see damage there. For all the tubas in cold climates, no one could think of one example.
- ice expands about 9 percent, that would be .00001 or .00002 inches.
- Dan performed an experiment with telescoping brass tubing, no observable difference after repeated cycles.

[PaulMaybery]

I remember that thread now. I would imagine though, that the inner telescoped tube, without any drill holes is significantly stronger than a piston. Any compression from the expanding ice would be a force distributed and directed inward and outward. The inward force vectors being much the same as the weight on a Roman arch. Depending upon the speed of the freezing, the crystalizing ice might have some time to migrate laterally and escape since it is not necessarily under pressure. On a high price precision instrument I would not care to risk the elements. Pistons are finnicky enough. again... just saying.