Breath condensate revisited

Irish Flute
1

Contacted a few days back by an owner of one of my flutes who had found his tuning slide had seized up. I told him of my theory that this is caused when we allow too much breath condensate to build up in the space between the inner and outer slides. It then finally congeals into a glue strong enough to defy our ability to twist it free.

And passed on my usual advice that introducing a hot metal rod up through the barrel socket to the overlap area, and rolling that rod around the inside of the slide will warm it enough to weaken the breath condensate glue, and let the slide come apart, usually at that point in time where you are about to give up in frustration!

Some time later, I remembered that not everyone was really convinced about the breath condensate theory, and wondered if there was a way I could test it. Without my thinking cap firmly in place, my default condition, I pulled apart the slide on my own playing flute, and wiped off the two mating surfaces with a tissue dampened with methylated spirits (de-natured alcohol). So I now had two clean surfaces.

I sat down in my thinking chair - a nice comfy recliner - and breathed on both tuning slide surfaces in turn. Onto the exposed section of the head slide, and into the empty slide protruding from the barrel. Rotating each victim to get good even coverage of anything that was in my breath. Not huffing or panting, just breathing. I believe I could see the surfaces become a little foggy, but hey, wishful thinking?

After a few minutes breathing, I slipped the slides back together again and rotated the head numerous times to spread any moisture around. I then left it overnight.

Today, I found the head not wanting to rotate. I was tempted to put some muscle into it, but then fortunately my pre-historic scientific training kicked in and a little voice said “measure it”. Err how, I asked the little voice, but it had shot through, no doubt to bother some other non thinkers. It must lead a very busy life!

What am I supposed to measure, I asked from the safety of my thinking chair. The rotational force required to break the condensate seal, the chair offered helpfully. “Torque”, it prompted. I was whisked back in time to high school physics, where our teacher opened the discussion on rotational force with the old gag “Wherever there is a couple, there will be torque.”

Hmmm, so what can I couple to my essentially cylindrical head to be able to introduce and measure some rotational force?

I settled on a retort stand flask clamp, this kind of thing:

So, I clamped the jaw of this thing to the head of my flute, held the barrel and started adding lab weights to the far end of the shaft which I had sticking out horizontally. At 400 gms, the head suddenly rotated. The clamp itself weighed almost 200gms, and more than half of that was sticking out, so we can guess it contributed say another 100gms. Making a torque of 500gms weight at about 200mm distance out.

At this point I suddenly thought, wouldn’t it have been good to measure the normal torque needed to rotate the head before the heavy breathing routine. Too late for that, but then I cleaned the slides surfaces once again with alcohol, greased them lightly with cork grease, rotated them and slid them in and out to distribute the lubricant, and then put the clamp back on intending the measure the torque now needed.

The off-centre weight of the clamp alone (we estimated at maybe 100gms) was now enough to cause the slide to rotate.

So, I think we’ve shown that breath condensate can be artificially introduced, and is capable of gluing a well cleaned slide closed after only a few minutes of application. And that we can easily come up with ways to measure the difference.

Hopefully, I’ve now convinced you all to go and clean your flute slides!

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I often wish there was some kind of like button on here - your posts are always entertaining and I love the scientific approach to everything. You are 50% of the value of this forum (and the other 50% do a great job too).

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Eeek, I’m down to just 50%?! I’m gunna hafto lift my game!

(snigger!)

4

Very interesting Terry!

Now to test what temperature is required to bring the torque required to within a reasonable percentage of the baseline so people don’t overheat and melt the glues!

5

Woah, getting trickier!

One of the complications is not knowing how stuck stuck is. Can a slide be just a little bit stuck, in which case a slight warming or even a good jerk would free it? My pretend stuck slide requiring 5 times higher torque than the same slide well cleaned and greased suggests that “slightly stuck” is possible.

And can it be really stuck, so that a lot of heat is needed? I’ve certainly encountered a few of these over the years, particularly in older flutes, modern and original. These defied any attempt to move them without heat, and required what seemed a lot of heat to break the bond. So that seems to confirm that we can have a wide range of stuckness.

So it’s probably not going to be just a temperature one has to reach, it might be a range, depending on how stuck the slide is.

I imagine a long slide as you find particularly on original flutes might also conduct more heat away from the junction than a flute with a short slide like I make.

How to measure temperature up the tube is an interesting challenge, but I do have a thermocouple temperature sensor on several of my multimeters, so that might be a way forward. I’ll try to remember to try it out if I run into another example.

Now, I mentioned using the old standby, a hot metal shaft rolled around inside the overlapping parts of the slide to heat and soften the bond. But something made me wonder if that’s going about it the hard way. What about harnessing the power of steam?

Imagine you attach a short length of tubing to a convenient source of steam, eg an old fashioned pressure cooker on the stove. You take out the stopper and cap, and hold the rest of the head, slide barrel combo vertically over the tubing so that the steam hits the inside of the overlapping part of the slides. That should heat the inner metal very quickly, so I’d imagine that you wouldn’t be there long. Easy to pull it off after a few seconds, try undoing it, putting it back on for a few more seconds, etc.

Don’t know, but good to think on next time any of us cops a nasty case. And they will come…

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And of course, any mention of flutes and steam evokes memories of a potential scandal back in 1759. Seems James Watt, later to be known as the father of the steam engine was also a musical instrument maker and flute player. And possibly a faker of flutes, as a fake stamp bearing the name T Lot was found in his workshop. Lot was a famous French maker at the time, so it would be a good name to snitch. I guess we’ll never know…

7

I’m a little confused.

Isn’t condensation going to occur only on the inside surface of the slide? If you never changed the position of the slide, the condensation would never get on the outside surface of the inside slide.

Or is it the case that condensation is suspected to seep into the area where the inside and outside slides touch, via the interface point exactly where the outside slide meets the inside one?

In my limited experience, stuck slides happen when you leave an instrument sitting for a long time without touching it (i.e., months). So this wouldn’t be condensation, but more likely oxidation. However, this indicates that oxygen can penetrate into the space between the slides, so thus condensation could too.

So the case would occur for someone who plays the instrument frequently but never moves the slide?

Because even if you didn’t clean the slide, if you moved its position frequently, you would break the adhesion before the necessary torque built up to an impractical value.

Your mention of James Watt makes me think that possibly this issue may have been addressed previously in the context of steam locomotive design. A literature search in an engineering library with archives going back to the early 20th century might conceivably yield some results to a dedicated researcher.

I am vaguely aware that there are issues of condensation pertaining to cold-starting a diesel locomotive, but this may be something else entirely.

8

You ask some great questions, fintano. I can’t guarantee to answer them all, but here goes!

Seems reasonable.

Or is it the case that condensation is suspected to seep into the area where the inside and outside slides touch, via the interface point exactly where the outside slide meets the inside one?

I’m thinking some seepage might occur, especially when you put the flute back in the case. And especially if you are in the habit of closing the slide after playing perhaps because the case cutout requires you to?

In my limited experience, stuck slides happen when you leave an instrument sitting for a long time without touching it (i.e., months). So this wouldn’t be condensation, but more likely oxidation. However, this indicates that oxygen can penetrate into the space between the slides, so thus condensation could too.

I don’t think it’s oxidation. Firstly, it happens with brass, silver and nickel plated slides, and combinations of these. But also, I can’t see heat breaking up oxidation, and I can’t see alcohol washing it off.

So the case would occur for someone who plays the instrument frequently but never moves the slide?

Interesting question. Honest answer, don’t know!

Because even if you didn’t clean the slide, if you moved its position frequently, you would break the adhesion before the necessary torque built up to an impractical value.

It might break up the adhesion, but if you imagine that you then add some more sticky liquid by playing it some more, that might seep in and redissolve the build up of condensate.

It is interesting to Google “sticky breath”. It seems to suggest some people have stickier breath than others, due to health and diet issues.

I’ve made flutes for myself in the past that have had an open C hole for the thumb. A downside is that in a long session, some of the condensate from the head makes it down to the C hole, and oozes out onto your thumb. And it’s really sticky!

Your mention of James Watt makes me think that possibly this issue may have been addressed previously in the context of steam locomotive design. A literature search in an engineering library with archives going back to the early 20th century might conceivably yield some results to a dedicated researcher.

There has been some work done - Google “james watt flute faker”. But I am not convinced it’s enough for a conviction!

I am vaguely aware that there are issues of condensation pertaining to cold-starting a diesel locomotive, but this may be something else entirely.

Yeah, I think quite a different technology!

9

One quick and convenient way to get sufficient heat inside a stuck head tube is to use a heat gun. If you pop out the stopper cork, orient the head tube vertically, and allow the hot air from the heat gun to rise up through the tube you can raise the temperature quickly and in a controlled way. My heat gun has a slow and a fast setting, and I tend to use the slow setting most of the time for this. You have to be careful about (a) how you hold the head tube, so as not to burn yourself, and (b) be careful about how the hot air is directed near the external wooden parts of the flute, but it isn’t difficult to do this without problems. Just go incrementally. The metal conducts the heat to where it is needed quite efficiently.

I’ve used the above method many times. I know it sounds extreme, and maybe a bit horrifying, but our wooden flutes are amazingly resilient to heat. If the heat does get misdirected, the first thing you will typically notice, on an antique flute, is that the shellac finish starts to bubble up. This is very easy to fix though.

As for using steam, I wonder if that approach might suffer from the problem of the temperature not getting high enough. For a severely stuck tuning slide, or to remove a glued in head liner from a cracked head, you need to get the slide and liner extremely hot.

10

In the meantime, I’m going to vote for Terry to design my patent tin whistle tuning device. :smiley:

It’s a hinged tool with two parts, one clamping to the head, the other to the body. The inner part that contacts the metal is padded so it doesn’t scratch, and the outside is built up to be nice and grippable. In use it probably looks like two mandarin oranges inexplicably speared on a length of pipe.

But it’s a much needed adaptation. People with hand impairments struggle to tune whistles that wouldn’t even reach the ‘stuck’ threshold on the ISBS (International Sticky Breath Scale); a tuning slide in the ‘usefully resistant’ category can be an intractable obstacle. And it’s hard to play a whistle where the slide moves so freely it ends a tune 30 cents sharper than it started if you have to look down to read music.

So over to you Terry, and Merry Christmas!

11

Woah, that’s a bold approach, to be sure. But yes, sometimes we are confronted by cases that require a bold approach. A flute that was put away 100 years ago having not been properly cleaned for the previous 50 would be a good example. Over such a long period, stickiness turns to stone.

I am reminded of the worst case I can remember being confronted by, that required me to hit the slides with my propane gas torch I use for soldering silver. Fortunately with this flute, the head and barrel timbers were cracked enough to let me remove the rings and peel the timber off, so I was only trying to separate naked slides. Even so I had to pour on an astounding amount of heat. The smell of burning paint filled the room, and I concluded that someone had wrongly lubricated the slides with linseed oil!

I did imagine that some kind of funnel might help direct the hot air gun’s energy to where we want it, rather than risking it messing with the shellac. But I couldn’t immediately imagine what such a funnel might look like. It would have to be metal to withstand that heat, and probably specially fabricated to fit the shapes involved. Tricky.

As for using steam, I wonder if that approach might suffer from the problem of the temperature not getting high enough. For a severely stuck tuning slide, or to remove a glued in head liner from a cracked head, you need to get the slide and liner extremely hot.

Steam does have the benefit of higher thermal mass than hot air, but yes, it probably depends on the case which method we need to escalate up to. I’ve since thought up a few more approaches we could consider.

What about boiling water? Boil the jug, and move the stopper down the head until its face is about where the top of the barrel slide protrusion is likely to be. Tip the head upside down, and pour the boiling water into the bore through the barrel socket. You could even make a sleeve to pop into the barrel socket to protect the wood from the worst of the onslaught if worried. Tip the water out, try rotating the barrel, repeat until enough heat transfers for long enough to melt the goup.

Or what about the spirit lamp we use to seat the pads in our keyed flutes? It heats the keys enough to melt shellac, and that should be more than enough heat. Mine has a stem about the depth of a barrel socket, so the heat would mostly go up the chimney, err, bore, which is where we need it.

So, that’s quite a few approaches. Can I make so bold as to set them out in a logical order of desperation and depravity? How about, starting at the mild end…

  1. spirit lamp?
  2. steam?
  3. boiling water?
  4. hot rods?
  5. hot air gun?
  6. propane gas torch, but only if the timber has come off?
  7. nuclear fusion reactor?

The question marks indicate that these are more questions at this point than answers. Perhaps when any of us strike a seriously stuck slide we could try several of these before going all the way?

And of course, the hardest question of all:
8. Other, please specify…

Any other bright ideas we should throw into the ring now?

Hmmm, I suddenly thought to reach into my collection cupboard behind me to check for stuck slides. All good up to no 10, a 5-key flute by French maker, Lecompte. The barrel turns relative to the head, but not easily. And it won’t come off.

Being a French flute, it has the typical short slide, just extending a bit into the head. So that might make it unsuitable for some of my proposed collection of methods. Looking down the barrel socket is a bit confusing too. I’d expect to see the end of the inner slide rotating inside the outer slide. But I seem to see the inner slide AND the outer slide rotating inside an extension of the metal lined socket. Three levels of tubing, not the usual two! So this may not be a fair test! This might not be a case of a stuck slide as much as a loose outer slide. Or more probably, both!

Oh, and with all this metalwork inside, no surprises that the barrel timber has cracked in 6 places! No surprise that it doesn’t pass the suck test!

But, given all that, what do we have to lose? It doesn’t play a note at the moment!

No rush on this one, so feel free to come back with any thoughts!

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Is there a danger that a failed attempt might make it harder for the next one? Something that might go gooey (say) with more heat gets baked into something harder?

As opposed to the other danger that being too aggressive may end up with damage when a slower, gentler approach might have worked.

I have broken several things when trying to fix them.

13

I’m no metallurgist or chemist, but I’ve long thought (based on??? old discussions here???) that there’s an element of galvanic or electrolytic leaching involved in the way tuning-slides get cemented together - alloys and bimetallic juxtapositions with a fluid context of some kind - penetrating water (breath condensate) or applied oil or even grease can potentially set up conditions for (very weak, slow) electrical currents which preferentially leach out and move certain parts of the metals, abstracting them from an anode and depositing them on a diode (if I have that the right way round)? Plus of course water includes oxygen and oxidation can and does take place underwater. The tendency of copper salts to leach out of any copper alloy and form verdigris is well known, by whatever chemical or electrochemical process. I don’t properly understand all this, but I know it can and does happen and it seems to be likely that it’s involved in this cemented slide phenomenon. It could account for the fairly fast effect Terry’s original experiment indicates, as well as the much tougher end results of long-term disuse without cleaning before storage.

I presume there’s scope for relatively simple experimentation to test for whether there are any galvanic currents in our context and how galvanic corrosion and deposition might work with our materials (brass or nickel-silver, possibly with tin and silver also involved) in a medium of hydrogenated grease?

14

Close. The (positively-charged) metal ions are taken from the anode (or sometimes from the electrolyte) and deposited on the (negatively-charged) cathode.

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Yes, always a danger either way. The worst problem we face in doing these repairs is we don’t always know all the facts, and so we are not in a good position to make best judgements. You’re about to see that unfold…

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Jem raised the question above about galvanic action, and it would certainly seem a possiblity that corrosion rather than stickiness is part of our problem. I’m not sure I’ve actually seen any evidence of it being the primary problem. We need to keep a lookout.

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Thanks for the correction, Tunborough! I knew I was misremembering details/terms but wasn’t in a position to check reference material before posting.

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Drifting a bit but, does it matter what beverage one consumes prior to/during playing as to what the make-up of the condensation is? Would that make an impact on the “locking” of the tuning slide (or perhaps any other impact on the instrument)?

Happy holidays.

Steve

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You’ll remember I set out a possible order of attack in the case of stuck slides. Already two minor amendments, right up the front…

  1. reasonable force?
  2. alcohol?
  3. spirit lamp?
  4. steam?
  5. boiling water?
  6. hot rods?
  7. hot air gun?
  8. propane gas torch, but only if the timber has come off?
  9. nuclear fusion reactor?

Thinking on reasonable force is that we’d be silly to jump straight into heating our poor heads without trying a bit of force first. Reasonable is not a very helpful descriptor though is it. I guess the kind of force that is unlikely to damage anything.

And alcohol. Solves some problems, but can create more! Remembering I recommended alcohol to wash off any condensate from slides, it occurred to me that we should try it as an early fairly harmless tool before getting into the hot stuff. The thinking is that it’s like penetrating oil - very thin - so if there is any chance of getting a solvent in between the slides, this would be the most probable. And because it is a solvent for the goup we expect to find, probably the most useful.

And remember I wasn’t in a hurry to try separating the Lecompte slides. But it’s sitting there, looking at me, laughing at me. How about I just try the alcohol?

My theory was to block the head bore between embouchure and tuning slide, hold the head barrel side up in the retort stand, and fill up to the top with alcohol, and leave it to soak in.

A fly in my ointment manifests immediately - remember the six cracks in the barrel? So I laboriously tape up the barrel with electrical tape, carefully overlapped to cover all the cracks. Carefully fill it with alcohol, and am suddenly aware of liquid expanding across the base of the retort stand. Turns out there are also two long thin undiagnosed cracks in the head! As an aside, it was amazing how well the alcohol exploited them and gave away their locations. Could be a useful tool for finding invisible cracks!

I toy with the idea of also taping up the cracks in the head, but come to the conclusion that this isn’t the way forward for this head.

So, spirit lamp is next. I remove all the tape and dry off the alcohol before adding fire!

Again, I found the retort stand great for supporting the head, barrel side down, over the spirit lamp, and the spirit lamp easily capable of making the slide very hot very fast - a minute or so and I’m finding it too uncomfortable to hold the outsides without some rags.

And I heat and I test and I heat more and test again, and so on for a long time. And am not getting anywhere. I’m starting to smell a rat. Has someone glued these slides together? Am I up against something like epoxy resin? I decided that it was getting too late to play nice.

Fortunately the slide was jammed with about 1 mm of gap between head and barrel showing. So, against all my better judgement, I heated it really hot, then introduced a screwdriver blade and twisted slightly. Oooh, a tiny sense of movement. Rotated and repeated on the other side, again a slight sense of movement. But by now it’s cooling, so back on the heat.

Slowly ever so slowly the gap widened. But I realised I wasn’t pulling the slides apart, I was pulling the head slide out of the head! Oh, well, what the heck, this is clearly a lost cause, let’s see where this might lead. And so I slowly managed to extricate the head slide, which had the usual scoring of the outside to provide the wood some grip, but looks like it also had a black tarry substance as a glue.

So, now I’m holding just the barrel with the head slide sticking out of it. I try heating the outside of the barrel slide, thinking if I could expand that, it might release the inner slide still attached. About this point, I thought I should be measuring the temperatures of these pieces. The head slide was up around 180C, while the inner slide around 140. Err what? Why the difference?

And a problem I now face is getting a good grip on the inner slide. It’s pretty short. I’m starting to wonder about all this.

So the thought comes back to me, what about 1. Reasonable force? How can I now apply reasonable force to something that’s hard to grab. Aha, what about pushing rather than pulling? So, I find a cylinder of brass that just happens to fit snugly inside the outer slide but not the inner slide, and using the lathe as a press, I gently press the inner slide out.

And then get confronted by the last thing I expected. The inner slide is wrapped in a thin film of plastic. Teflon plumbers tape! Who would have guessed? So, no wonder heat didn’t affect it, it melts at 327°C!

And of course that explains the difference in temperature I noted above between the two slides. The Teflon tape is an insulator!

Peeling the tape off, I noted the inner slide looked clean. It slid easily into the outer slide. Too easily, it also slid around and out again easily. So this is probably why someone introduced it. And then couldn’t get the slides apart ever again?

I must admit I wouldn’t have thought Teflon tape could bind the slides so firmly, but there you go. We don’t know how much force they applied to the parts to get them together - that Teflon was under very high compression.

So, as an experiment to test for best approaches to breath condensate stuck slides, it hasn’t been a success. But it is a reminder to all who would attempt to repair old flutes. Be forever suspicious. You might be dealing with foul play!

20

Sounds as if Teflon tape, if used at all, should only be used (temporarily) on loose-fitting body tenons. Grease only (possibly thicker than usual), if necessary, on slides.