what humidity and how do you keep it?

[GaryKelly]

OK, time for an objective Peer Review of your observations, Terry.

You started with an oiled flute of 338.5g, and you set this figure as "0".

After playing for 30 minutes, it weighed an extra gram, but after mopping out, that reduced to 0.3gms.

Step 1. The flute now weighs + 0.3g

After an hour, it wieghed 1.3gms more, then .4gms after mopping.

Step 2. Your flute now weighs 0.4g more than in Step 1. Step 1 plus 0.4g = + 0.7g

(GK paraphrasing...you played, you ate, you mopped out, you went home)
Thinking to wrap up the experiment, I weighed the flute again. Now it weighed
0.7gms - it had gained an additional 0.3gms since the second mop out!

No it hadn't. Step 1 plus Step 2 = 0.7g

I measured it again after about 24 hours from the start. 0.8gms. This pesky flute is still gaining weight a day later!

Your apparatus is accurate to plus or minus 0.1g and therefore the reading represents nothing more than expected limits of experimental error. Furthermore, in not describing your test environment, an objective reviewer must point out that your experiment may have suffered external interference beyond you control; for example, a fly or crawling insect may have entered the flute without your knowledge and skewed the results. This isn't a fatuous remark. This is objective peer review.

At 40 hours, dropping back at last to 0.6gms.
At 65 hours, 0.3 gms
At 91 hours, back to 0.1gms heavier than at the very start.

Why the "at last to 0.6g"?

So how come the flute continued to gain weight even after I got home?

It didn't. See above.

So, what did we learn? That an unlined flute certainly gains moisture during playing - I'm sure we could have guessed that.

You're implying that the moisture somehow found its way into the material of the flute. It didn't. What you've been measuring is surface water, and the evaporation thereof. Not moisture loss from within the wood, nor the wood sucking moisture out of the air or from the condensate.
No amount of 'the usual' mopping out will remove the surface water which clings by surface tension to the seam between the end cork and the headjoint walls.

You don't tell us what material the end cork is. If it's just a cork cork, then it is much more porous than, say, a faux ivory stopper lapped with cork. If it's faux ivory or plastic, or indeed just cork, condensate will bead and cling to it. I doubt very much you managed to remove that with your mopping. (Similarly any surface water clinging in the tone-holes).

Similarly, when you mop out, you also mop out the non-drying oil you've applied. You end up with an emulsion (water plus oil) on your mop, and an emulsion in the bore. The water in the emulsion may be considered surface water, for it will out by evaporation.

We learned that leaving the flute wet permits moisture to continue to soak in - you might as well be playing. This reminds us always to mop out after playing, and in situations like summer schools to mop out continually throughout the day.

Excellent advice, but this is not what we learned from your observations.

But the Dampit-style humidifiers - a piece of sponge in a
capped length of poly tubing with a few holes in the side will no doubt work
wonders. Buy one or make one if you live in a dry climate and have a lined
flute. Ideally buy a little hygrometer too. A few dollars worth is cheap
insurance for a flute worth thousands.

Your observations don't support this. I know why you're saying it, but in an objective peer review your conclusions must be drawn from the data. Really, the only thing you've proved is that surface water evaporates. Your closing sentence implies that unless someone humidifies the air in their flute-case, their costly investment and beloved flute will suffer some sort of catastrophe. You simply can't say that based on the observations above.

And we learned that something damp - even as simple as a damp cleaning rag - inside the case will keep your flute humidified.

Actually we didn't learn this from your observations. The only conclusion that can be drawn from your observations is that water evaporates. It's true though that a damp thing will humidify the air around it, depending on the temperature, pressure, and RH of the air at the start.
End of peer review.

Terry, we can't replicate your experiments for many reasons. Obviously we can't manufacture experimental headjoints for one thing. And many of us don't have scales with an accuracy of plus or minus 0.1g. You also haven't told us enough about your test environment for us to faithfully reproduce your results.

I've conducted a couple of experiments myself (a third is ongoing). I'm sorry I can't "publish" them now, I need to upload to my server and I can't do that over a cellphone connection (which is what I'm on here at home!). But tomorrow morning I shall. There are two experiments which are easy to replicate and simple enough that a child could conduct them. I hope you'll review them vigorously, and I also hope that you and others here will attempt to replicate them and post your results. (again, apologies for not having the bandwidth at home to upload my data and photographs, there's nearly 4MB of the stuff and it'd take something like 4 hours to do on my cellphone!).

[Terry McGee]

OK, time for an objective Peer Review of your observations, Terry.

Um, might I ask why? Doesn't anyone understand the meaning of the term exploratory any more? I'm not seeking to publish in the Journal Of the Acoustical Society of America, I'm reporting some interesting and relevant experiences to a bunch of fellow flute players on an internet forum. Consequently, I'm keeping data to the bare minimum needed to convey the story.

After an hour, it wieghed 1.3gms more, then .4gms after mopping.

Step 2. Your flute now weighs 0.4g more than in Step 1. Step 1 plus 0.4g = + 0.7g

No, it weight 0.4gms more than it weighed at the start. That was the point of the 0 reference, all subsequent measurements are referenced to it. So all your subsequent calculations and conclusions based on them are wrong.

Terry

[sturob]

Um, might I ask why (peer review)? Doesn't anyone understand the meaning of the term exploratory any more? I'm not seeking to publish in the Journal Of the Acoustical Society of America, I'm reporting some interesting and relevant experiences to a bunch of fellow flute players on an internet forum. Consequently, I'm keeping data to the bare minimum needed to convey the story.

Sure, I understand exploratory. But they're at best interesting, and no conclusions can be drawn from them. It'd be the equivalent, if you'll pardon the comparison . . . it'd be the equivalent of someone saying, "You know, I bought this flute from Mr. McJay, and it cracked. What have we learned? That Mr. McJay's flutes CRACK! Steer clear!"

Gary was deconstructionist and I was more a gestalt-reader, but I think Gary and I came to similar conclusions that your findings could be explained simply by the evaporation of water from the surface of the flute.

I guess, in my own opinion, you can't say that a certain set of observations is merely exploratory, and not subject to scientific deconstruction, but that those very observations are valid ones from which to advocate a particular course of action.

Maybe I'm too steeped in the Eurocentric scientific method, and we need some kind of neotantric transcendental approach to flute care. Perhaps our flutes absorb moisture when our music lacks passion?

Stuart

[Terry McGee]

Gary was deconstructionist and I was more a gestalt-reader, but I think Gary and I came to similar conclusions that your findings could be explained simply by the evaporation of water from the surface of the flute.
Stuart

But Gary was also wrong - he simply misread the data I provided. The flute did gain weight after its final mop out. Indeed it gained as much weight after I stopped playing as it had while I was playing. Do you still think this can be explained by losing water from its surface?

Perhaps there was a temporary gravity surge?

Terry

[sturob]

You're assuming the mop-out got rid of all the water on the flute. Half a CC of water on the surface of even just the bore would probably be nearly undetectable . . . unless you weighed the flute on a really accurate scale.

As for its continuing to get heavier . . . do you really think half a gram isn't within the margin of error for that scale? As you know, resolution and precision aren't necessarily on the same scale, to coin a phrase.

Stuart

[Dana]

Of course wood absorbs moisture. I said it, therefore it's a scientific fact!!!

[Terry McGee]

You're assuming the mop-out got rid of all the water on the flute.

I imagine it didn't, but that's not the issue. The issue is that it continued to gain weight after I stopped playing. So any remaining moisture should have evaporated and reduced the apparent weight gain.

Half a CC of water on the surface of even just the bore would probably be nearly undetectable . . . unless you weighed the flute on a really accurate scale.

Argghh! I did, I did! And it was easily detectable - 4 times larger than the resolution of the scales.

As for its continuing to get heavier . . . do you really think half a gram isn't within the margin of error for that scale? As you know, resolution and precision aren't necessarily on the same scale, to coin a phrase.

Stuart

Indeed. But remember the scales were recalibrated at two points of the scale (0.0 and 100.0 gms) before every reading. It's lovely to see that auto-recalibration process work, and then put the calibration weight back on and see it read 100.0 gms every time. Even if the scale's accuracy was suspect, we're only interested in the change in weight, not the weight itself.

Also, if no absorption and evaporation were happening, and some random error was sneaking in, we'd expect a lot of random readings around the original weight, not the nice curve we saw in the readings.

I think we might just have to face facts. What I said happened did happen. Having thought about it it makes sense that it did happen. Now to argue it didn't happen you would need to come up with a more plausible explanation that fits the known facts.

Terry

[GaryKelly]

After an hour, it wieghed 1.3gms more, then .4gms after mopping.

Step 2. Your flute now weighs 0.4g more than in Step 1. Step 1 plus 0.4g = + 0.7g

No, it weight 0.4gms more than it weighed at the start. That was the point of the 0 reference, all subsequent measurements are referenced to it. So all your subsequent calculations and conclusions based on them are wrong.
Terry

I can only go by what you tell us. You said it weighed 1.3gms more, then .4gms after mopping. If you don't mean it weighed more than your previous measurement, then kindly don't use the word more.

You'll also note that you 'played a little, ate, mopped out, went home.' The first time you played, the bore picked up .3g of water. You told us so. You then said it picked up .4g more, but now you're losing credibility by telling us it didn't, and that it only picked up .1g more. So if the flute picked up .3g the first time, why couldn't it have picked up another .3g the third time of playing and mopping out?

Finally, you've told us your scales are only accurate to 0.1 g. The difference between 0.7 and 0.8 is 0.1 But given the limits of your scales it's entirely possible that the 0.7 displayed was actually 0.799999g but of course you scales won't display that. Then a mote of dust weighing 0.0000001g floats down from the ceiling and bingo, your meter reads 0.8g and you're running around announcing to the world that your flute gained weight.

The reason why people are so interested in reviewing your observations is because they want to understand why flutes crack. They're hoping you're right. But nothing you've told us so far supports your theory and your observations certainly don't. You need to be far more scientific than this. There are too many people around willing to believe everything they read without asking the most fundamental questions. A point I believe Dana made quite succinctly.

In a couple of minutes you'll have the chance to review two experiments of mine. I hope you will. I hope you'll replicate them, particularly since you've told us you have a hygrometer with a ±0.2% accuracy.

[GaryKelly]

Experiment 1 contains Control A, and the experiment itself also serves a control for Experiment 2.

Experiment 1

Purpose: To examine the rate at which a fixed volume of air at a constant temperature will absorb moisture until saturation (RH 99%)

Apparatus: Digital thermometer/hygrometer. Ziplock bag. Kitchen paper. Approx. 5ml tapwater.

Control: A. The thermometer/hygrometer was placed within the Ziplock bag, which was left open to atmosphere for a period of 12 hours. The bag was then sealed and the hygrometer reading noted. After 24 hours, the reading on the hygrometer remained unchanged (which was to be expected). The bag was then opened to atmosphere for a further 12 hours. Temperature was controlled by ambient central heating thermostat and pressure within the sealed bag of course remained constant.

Method: Approximately 5ml of cold tapwater was applied to a piece of paper kitchen towel, and the moistened paper towel pressed gently into a wad. The moistened wad was then inserted into the Ziplock bag, taking care to ensure that the wad did not contact the hygrometer. The bag was then sealed. The hygrometer reading was taken at intervals and recorded using digital photography.

Results: Humidity within the sealed bag rose to saturation (which was to be expected), with saturation occurring at an indeterminate time between 802 and 1341 minutes after the experiment began. The experiment commenced at 1802hrs on Day 1, and was terminated at 1643hrs on Day 2, (22 hours and 21 minutes total). Tabulated results are as follows:



Observations and conclusions:
It can be seen that an initial rise of 20% in RH took only 24 minutes. But thereafter, a further rise of only 15% took 73 minutes. From that point, the rate of increase of RH slowed dramatically, a further 10% rise from RH 70% to RH 80% taking 143 minutes (or 2 hours 23 minutes). This slowing of the rate of uptake of moisture was to be expected, since the volume and temperature of the air remained constant (note that although temperature varied by a few degrees Fahrenheit, this is well within acceptable limits for this experiment). This is why, for example, it takes longer for washing to dry on a line on humid days.

At the end of the experiment, the moistened wad was removed from the bag and squeezed out. It appeared that a full teaspoonful of water was obtained, but of course this observation has no merit since a calibrated amount of water was not used and no precise measuring equipment was available to determine the exact amount of liquid water evaporated into water vapour necessary to raise the air in the bag to saturation.

The capacity of the Ziplock bag (a “Hefty One-Zip” of American manufacture), which measures 8 inches by 7 inches, is approximately 1 Litre when filled with water. However, it must be noted that filling the bag with 1 Litre of water results in the sides becoming considerably distended. It will be noted from the photographs taken during the experiment that the bag is neither inflated nor distended, and that the thermometer/hygrometer occupies a considerable portion of the space within the bag.

It should also be noted that there was no agitation of the fixed volume of air contained within the bag, and that the results are in accordance with the known and proven properties of a fixed volume of air at STP.

You can see digital photographs of the experiment and download a Word document of it here: http://www.gjk2.com/exp1/exp1.htm

[GaryKelly]

Experiment 2. This is the one I hope folks will take the time to try for themselves and report back their results.

Experiment 2

Purpose: To examine the rate at which a fixed volume of air at a constant temperature will absorb moisture from the headjoint and barrel of a wooden flute.

Apparatus: Digital thermometer/hygrometer. Ziplock bag. Headjoint and barrel of a wooden flute (unplayed and ‘open to atmosphere’ - in a simple case without artificial humidification - for 24 hours prior to the experiment).

Control: See experiment 1, control A, and also Experiment 1 itself.

Method: The thermometer/hygrometer was placed within the Ziplock bag, which was then left open to atmosphere for a period of 12 hours. The headjoint and barrel of a Bleazey D wooden flute, which had remained unplayed for 24 hours and left in its case (without any artificial humidification), was then placed inside the bag, and the bag sealed. The hygrometer reading was taken at intervals and recorded using digital photography.

Results: After three days (71 hours 57 minutes) no change in the hygrometer reading (43%) was noted.

Observations and conclusions:

No measurable increase in the RH of the air contained within the bag could be detected after 71 hours and 57 minutes, after which the experiment was terminated. The flute is ‘partially lined’, with the tuning-slide liner terminating approximately 1 inch from the embouchure hole. It should be noted that the digital hygrometer presents a two-digit display, so the accuracy of the readings taken are therefore to one significant figure.

It is unknown whether the internal electronics of the hygrometer carry out “rounding up” or “rounding down.” Thus, it must be conceded that it is quite possible that at the start of the experiment, the actual RH of the air in the bag was 43.0%, and at the end of the experiment three days later, 43.9%. But it is also possible that “rounding up” or down takes place in the meter. It is of course possible that the actual RH in the bag was 43.x% and remained constant. All that can be said is that “no measurable increase was detected.”

Notwithstanding the limited accuracy of the device, given the small volume of air contained within the sealed bag (the headjoint and barrel together with the hygrometer occupying most of the available space) then a commensurately small amount of water evaporating from the wooden components should have triggered at least a 1% rise in measured humidity.

Within 3 minutes of the hygrometer being removed from the bag at the completion of the experiment, the reading fell to 38% (the RH of my living-room at the time).

The flute was last oiled internally using a proprietary almond oil/tocopherol preparation on the 9th of January 2005, which is 3 weeks and 3 days prior to the commencement of the experiment. After playing, the bore of the flute is swabbed out, and the exterior of the entire flute wiped down with a soft yellow cloth onto which is occasionally sprayed a proprietary furniture polish (“Woodsilk”, a non-silicone-based aerosol product containing “beeswax and nutrient oils”).

The Bleazey keyless D flute in mopane was purchased new from the maker in April of 2004, though it is a brass-ringed/brass slide older model (discontinued in early 2004 in favour of nickel-silver furniture and slide) and thus may have been “in stock” for some months prior to purchase. Phil Bleazey is an English maker, and thus the flute is ‘local’ to the UK.

The flute was played for two hours, two days before the experiment began, and after swabbing out and wiping down, left in its case (a canvas-covered, velvetystuff-lined zip-up wooden two-flute carrier purchased from Bigwhistle.co.uk) for 24 hours prior to the commencement of the experiment. This was to permit any surface water within the flute which the swab did not pick up (around the edges of the headjoint cork, for example) to evaporate naturally. No artificial “humidifying measures” are taken.

In conclusion, my results are certainly not congruent with the findings reported by Terry. Perhaps my use of “Woodsilk” on the exterior of the flute assists in some way in significantly reducing the amount of moisture egress/ingress that he reports in his experiments. However, it must be noted that the RH of the air in the bag remained at a constant (as indicated) 43%. Unless the humidity here in my flat drops to around 20% (which I shall of course monitor) and since I can’t artificially achieve such low humidity levels at STP, I can’t repeat the experiment at those levels of RH.

As you probably know by now, I have never worried about humidity affecting my flutes; they’re regularly played (daily, in rotation) so they get a couple of hours’ of my breath at least every 3 days with hours more at weekends, and I’m not going to take any extraordinary measures in respect of humidity just now. But this is not to say that those of you living in foreign climes should not. Especially since you likely don’t own a Bleazey and maintain it exactly as I do, in an environment exactly like my living-room here in Swindon.

If were obliged to abandon my flutes (a long holiday perhaps, or some catastrophe) for any length of time I probably would include a damp cloth in their cases, if only to prevent the need for prolonged “breaking-in” again on my return. But I’d still give them a decent period of breaking-in after a long absence.

I fully agree with Terry et al when it comes to swabbing out during intervals between playing and afterwards. I’d also recommend polishing the flute afterwards, if only because it keeps a lovely piece of wood looking lovely (although it’ll be interesting to see if anyone replicates this experiment who doesn’t polish their flute and gets radically different results to mine!).

Experiments 1 and 2 can be replicated easily by anyone anywhere who has the simple apparatus listed. It’d be great if some of you folks could take the time to do so and let us have your results.

Experiment 2 is of the greatest interest, since Experiment 1 is really only a pair of ‘controls’ (they prove that the equipment works, and that the bag is airtight). Note that if you’re using a tupperware box instead of a “Hefty One-Zip” bag (my thanks to Debbie in Chicago, she ships me red-cross parcels of Folgers Coffee sachets in them!) then you probably won’t be able to note the hygrometer reading through the lid. In which case, you can replace the lid with ‘clingfilm’ as long as you get a good seal. Remember to leave the flute unplayed and without artificial humidification for a day (in other words, don’t store it in a sealed container with a ‘dampit’ or other humidifying device) so that any surface water left around the headjoint cork from your playing has a chance to evaporate. Otherwise your results will be skewed!

You can see the digital photographs and download a Word document of the experiment here: http://www.gjk2.com/exp2/exp2.htm

[Terry McGee]

Um, why should the humidity in the bag vary? The head and barrel have equilibrated to the RH in the room, then you close the head & barrel and the hygrometer into a sealed bag. Humidity cannot leave or enter the bag (apart from by diffusion which is pretty slow). It won't enter or leave the wood as the wood and the air in the bag are already equilibrated. We knew that.

In the earlier experiment, you actually proved what you did not believe, that a wet mass of cellulose (variously a wad of paper towel or a wooden flute) can exchange moisture with the air. In your case, the cellulose was very wet, so a lot of moisture left the cellulose to join and indeed saturated the air. We knew that.

Now try enclosing the flute parts and the wet paper in the bag with the hygrometer. After a few days remove the wet paper, reseal the bag and continue monitoring. What is the humidity level in the wood now?

Have you noticed we're largely talking to ourselves?

Terry

[GaryKelly]

Have you noticed we're largely talking to ourselves? Terry

Curious isn't it! Maybe the thread's getting too big for people to bother with? Can't believe that, since flute cracking is a subject dear to so many hearts around here.

Re experiment 1, yes I was expecting exactly those results, so it's not a case of 'proving what I didn't believe'. Exp.1 really is just a pair of controls for experiment 2. What I didn't believe (and still don't) is that a wooden flute is capable of instantaneous moisture exchange with the air around it, the wood's simply too dense.

Your inference that the headjoint had reached 'equilibrium' with an RH of 43% is an intelligent one, and one I'd already considered myself, but the trouble I have is testing that conclusion. Also, if you'll pardon the pun, it doesn't hold water unless the RH in my living-room was 43% for the 24hrs prior to the experiment (it wasn't, the meter read 35% the day before and as you can see, 43% on the day of the experiment, followed by 38% after the experiment was terminated).

Unless wood is capable of instantaneous moisture exchange with the air around it I would've expected some exchange of moisture between the flute and the air in the bag, one way or the other, if the hj is as hygroscopic as you've suggested.

Now try enclosing the flute parts and the wet paper in the bag with the hygrometer. After a few days remove the wet paper, reseal the bag and continue monitoring. What is the humidity level in the wood now?

In the wood? I have no idea. But the RH of the air in the bag will rise to 99% (if there's enough water on the paper for the volume of air in the bag). Then when the wet paper is removed (in an air-lock so that no new dry air can flood in and queer the reading) the RH will remain at 99%...

This experiment wouldn't work, because if you're right, and the headjoint instantaneously sucks moisture out of the air until its EMC is equivalent to its surroundings, the RH in the bag would remain at 99%. If I'm right, and that headjoint of mine exchanges no moisture with the air around it, the meter will still continue to read 99%.

To test the equilibrium theory I'd need to find a way of keeping the hj at one level of RH, then transferring it immediately to a sealed environment containing a different RH, without cross-contamination. A challenge indeed. I shall put my thinking-cap on.

I think we need to wait for America to wake up before someone else chimes in!

[Terry McGee]

Now try enclosing the flute parts and the wet paper in the bag with the hygrometer. After a few days remove the wet paper, reseal the bag and continue monitoring. What is the humidity level in the wood now?

This experiment wouldn't work, because if you're right, and the headjoint instantaneously sucks moisture out of the air until its EMC is equivalent to its surroundings, the RH in the bag would remain at 99%. If I'm right, and that headjoint of mine exchanges no moisture with the air around it, the meter will still continue to read 99%.

OK, try it, but don't use too much moisture in wetting the paper. If there's much too much moisture, you could overwhelm the flute's ability to absorb at a high enough rate and it will be weeks before you see a result. Too little and your humidity meter won't react to it at all. A few mL (up to a teaspoonful) should be fine.

I'd expect to see the humidity in the bag rise (as it did in your experiment 1), until moderated by the flute starting to absorb it. So while your empty bag quickly reached saturation, the bag with the flute in it should stop short of that. (Providing, as I said above, there isn't so much water available that the flute has no chance of absorbing it at the rate it's evaporating). I'd expect after some initial argy-bargy an equilibrium to be set up, with the flute, the paper and the air all sharing in the available moisture.

When you whip the now only damp paper out and reseal the bag, you might expect to see a drop in the hygrometer reading - some of the moist air inside will have escaped and been replaced by drier air from outside. But I would expect the hygrometer to return to almost the same level as moisture now leaves the flute to rehumidify the air in the bag.

Having determined this, you might as well terminate the experiment, as from now on you are now just measuring the rate of diffusion through the bag, which should be slow. I imagine these snaplock bags are something like UHMW (Ultra High Molecular Weight) Polyethylene. But perhaps I hope for too much!

If you have access to a scale, you could measure the weight of the head before and after to confirm a weight gain. And if you have calipers, measure the maximum and minimum diameters at some point not too close to a ring (which will attempt to iron out change). The minimum diameter is more interesting as it changes more.

Terry

[lesl]

Good morning folks,

I'm a fan of both Terry and Gary, but dearie me! I hate to see my
favourite boyfriends arguing. and I think I've lost the thread of this
thread.

I think a flute absorbs humidity cos the headjoint is always
tight to come off after a lot of playing, and even worse in a humid
environment. (not scientific of course but anecdotal.)

Terry, do you know, how come flutes aren't generally made with the
end grain sealed?

Gary how can it be so dry in your house! I've always said when I
lived in England it took my knickers 4 days to dry on the line. Before
the change to central heating I guess. Do you think played flutes drip
more in a low humidity or high? or is it the ambient temperature makes
the difference?

At one point I thought it was important to buy a flute made in a similar
geographical area to account for the humidity in the workshop. I recall
a tech sheet from Taylor guitars giving the specs of their workshop
humidity for the same reason - to tell the owners how humid to keep
the instrument and prevent the wood cracking. They build the
guitars in a humidity controlled environment. Is this relevant?

Lesl

[GaryKelly]

I think a flute absorbs humidity cos the headjoint is always
tight to come off after a lot of playing, and even worse in a humid
environment. (not scientific of course but anecdotal.)

I've noticed this occasionally too, and have always blamed the lapping on the tenons. Cork is a veritable sponge compared to blackwood, and on my flutes most (if not all!) of the grease I apply to the corks gets scraped off when I assemble the flute. It squirts out of the seam between the two joints as I twist them together, so I have wipe off the excess before playing.

Gary how can it be so dry in your house! I've always said when I lived in England it took my knickers 4 days to dry on the line. Before the change to central heating I guess. Do you think played flutes drip more in a low humidity or high? or is it the ambient temperature makes the difference?

Central heating and double-glazing I think! My knickers dry overnight on the clothes-horse in the spare room. Flute dripping is a combo of temperature and humidity. The higher the humidity, the less the air can absorb the condensation produced in the flute. The amount of condensation depends on the temperature difference between the flute and your breath. If the flute is at body temperature then no condensation would form when you play it, thus no drips.

I recall a tech sheet from Taylor guitars giving the specs of their workshop humidity for the same reason - to tell the owners how humid to keep the instrument and prevent the wood cracking. They build the guitars in a humidity controlled environment. Is this relevant?

Relevant to Taylor guitars I'd say. Terry will doubtless say it's equally relevant to flutes, but I would disagree. A guitar soundboard is extremely thin and very long and wide (compared to a flute, for example), so I can understand why they would be sensitive to drying out and warping over time, far more so than a short fat thick-walled headjoint.

Anyway, he said, pouting, we're not arguing, we're debating...