I have wondered what you eat down there since you said the cockattoos are too tough. ( but you did say "and out again ?).
I understand that the larger lizards are good eating. Assuming that you are fussy in OZ !
I have just remembered that you asked of oxidation whether it is a surface effect or deeper. If the water can get in and out the oxygen sure as hell can.
Having said that I have to ponder the need to drill out to get a satisfactory result.
DuuuuuH !!
what humidity and how do you keep it?
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GaryKelly
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When I was at college, I once knew a girl in Penzance called Trilby, but not as well as I would have liked, for she eschewed my advances in favour of some hairy moustachoid Bermudan Svengali who treated her cruelly before unceremoniously dumping her (along with several others as I recall). Serves her right, says I.
Anyway. Look into my eyes...
I thought it might be valuable in a thread with over 150 replies to produce a Summary of the cases so far, and I hope I manage to state it fairly. Two cases are being heard:
Flutes Vs Humidity
Flutes Vs Temperature
In the case of Flutes Vs Humidity,
The Prosecution alleges that drops in ambient RH (sudden or otherwise) will oblige a wooden flute's headjoint and barrel to shrink, and that since this shrinkage is resisted by the metal liners of a tuning slide, the 'irresistable force meeting an immoveable object' will result in the wood cracking. The Prosecution introduces as evidence a property of wood known as "Equilibrium Moisture Content" (EMC) citing it as the principle mechanism responsible for this shrinkitudiness. Several witnesses have been produced, primarily the large number of English-made wooden flutes which suffered cracking in India when that nation was the jewel in Bessie's crown, and also the results of the Prosecution's own tests, which are currently ongoing.
The Defence, however, argues that EMC is such a long-term process that it surely cannot affect a flute that is regularly played. Nor can it explain the sudden cracking of a lined flute newly-made, purchased, and used in the same locale. Similarly, the Defence argues, Humidity cannot be responsible for the cracking of an English-made flute which has remained all its life in England, whether played or not.
Indeed, says the Defence, the Prosecution in describing the process of seasoning (a process he tells us takes years) is in fact describing the mechanism of EMC. As for the large numbers of flutes perishing in India, the Defence maintains that Humidity is innocent, and offers his own witness in the form of some 3 million India Pattern Brown Bess muskets manufactured in Birmingham and London in the same era, several hundreds of thousands of which were shipped to the same subcontinent, and which did not suffer harm in spite of the significant lengths of their stocks (the barrel-channels of which being as thin in places, if not thinner, than the walls of a wooden flute). Indeed, a good number of these original muskets are still in use today by muzzle-loading enthusiasts around the globe, with many more extant in private collections.
Furthermore, Defence points to the large numbers of antique wooden artifacts, both indoor and outdoor, many of which are imported and exported, which also suffer changes in RH with no apparent ill effect.
As to the experiments currently being conducted by the Prosecution, the Defence cannot cross-examine until the full results and, most importantly, methodology are known. For if the experiments are sound, and dramatic shrinkage does occur within a matter of days as the Prosecution claims, preventive action can be quickly and easily taken.
In the Case of Flutes Vs Temperature
The Prosecution argues that the chief destructive agent responsible for flute crackage is Temperature, and cites as evidence the laws of physics. He argues that the metal liners of a tuning slide expand and contract with temperature changes (the most significant of which occurs when playing the flute) and that this expansion applies a bursting pressure (hoop stress) to the headjoint and barrel walls. On contraction, the hoop-stress is somewhat relieved. This, the Prosecution alleges, is a mechanism by which a flute may be destroyed either promptly or after an indefinite period of time (stress-fracturing). He also points to the very considerable day/night temperature changes in locations such as India and offers them as the prime suspect in the cracking of wooden flutes during the days of Empire.
Many witnesses have presented themselves in support of the case, and indeed the Prosecution is grateful to the Defence for providing the most damning evidence of all, which is the methodology used by flute-makers of old (and apparently in some cases still to this day) of introducing hoop-stress during manufacture (hammering in the liners) and of compromising the structural integrity of the flute's bore by the practice of deliberately burring the liners before forcing them into position.
The Defence argues that the expansion and contraction of the metal liner is too small to cause dramatic effect, although he concedes that it might be the 'last straw' which could trigger a crack after the headjoint and barrel have shrunk to a critical condition as a result of a reduction in Humidity.
The Prosecution concedes that he is unable to produce exact (nor indeed approximate) figures by calculation of the pressures generated by the thermally-induced expanditudiness and contractionicity of the liners, and instead provides evidence by way of analogous models (the classic "fire sprinklers, single malts and drawing-pins" manoeuvre).
I think that sums it up so far?
Anyway. Look into my eyes...
I thought it might be valuable in a thread with over 150 replies to produce a Summary of the cases so far, and I hope I manage to state it fairly. Two cases are being heard:
Flutes Vs Humidity
Flutes Vs Temperature
In the case of Flutes Vs Humidity,
The Prosecution alleges that drops in ambient RH (sudden or otherwise) will oblige a wooden flute's headjoint and barrel to shrink, and that since this shrinkage is resisted by the metal liners of a tuning slide, the 'irresistable force meeting an immoveable object' will result in the wood cracking. The Prosecution introduces as evidence a property of wood known as "Equilibrium Moisture Content" (EMC) citing it as the principle mechanism responsible for this shrinkitudiness. Several witnesses have been produced, primarily the large number of English-made wooden flutes which suffered cracking in India when that nation was the jewel in Bessie's crown, and also the results of the Prosecution's own tests, which are currently ongoing.
The Defence, however, argues that EMC is such a long-term process that it surely cannot affect a flute that is regularly played. Nor can it explain the sudden cracking of a lined flute newly-made, purchased, and used in the same locale. Similarly, the Defence argues, Humidity cannot be responsible for the cracking of an English-made flute which has remained all its life in England, whether played or not.
Indeed, says the Defence, the Prosecution in describing the process of seasoning (a process he tells us takes years) is in fact describing the mechanism of EMC. As for the large numbers of flutes perishing in India, the Defence maintains that Humidity is innocent, and offers his own witness in the form of some 3 million India Pattern Brown Bess muskets manufactured in Birmingham and London in the same era, several hundreds of thousands of which were shipped to the same subcontinent, and which did not suffer harm in spite of the significant lengths of their stocks (the barrel-channels of which being as thin in places, if not thinner, than the walls of a wooden flute). Indeed, a good number of these original muskets are still in use today by muzzle-loading enthusiasts around the globe, with many more extant in private collections.
Furthermore, Defence points to the large numbers of antique wooden artifacts, both indoor and outdoor, many of which are imported and exported, which also suffer changes in RH with no apparent ill effect.
As to the experiments currently being conducted by the Prosecution, the Defence cannot cross-examine until the full results and, most importantly, methodology are known. For if the experiments are sound, and dramatic shrinkage does occur within a matter of days as the Prosecution claims, preventive action can be quickly and easily taken.
In the Case of Flutes Vs Temperature
The Prosecution argues that the chief destructive agent responsible for flute crackage is Temperature, and cites as evidence the laws of physics. He argues that the metal liners of a tuning slide expand and contract with temperature changes (the most significant of which occurs when playing the flute) and that this expansion applies a bursting pressure (hoop stress) to the headjoint and barrel walls. On contraction, the hoop-stress is somewhat relieved. This, the Prosecution alleges, is a mechanism by which a flute may be destroyed either promptly or after an indefinite period of time (stress-fracturing). He also points to the very considerable day/night temperature changes in locations such as India and offers them as the prime suspect in the cracking of wooden flutes during the days of Empire.
Many witnesses have presented themselves in support of the case, and indeed the Prosecution is grateful to the Defence for providing the most damning evidence of all, which is the methodology used by flute-makers of old (and apparently in some cases still to this day) of introducing hoop-stress during manufacture (hammering in the liners) and of compromising the structural integrity of the flute's bore by the practice of deliberately burring the liners before forcing them into position.
The Defence argues that the expansion and contraction of the metal liner is too small to cause dramatic effect, although he concedes that it might be the 'last straw' which could trigger a crack after the headjoint and barrel have shrunk to a critical condition as a result of a reduction in Humidity.
The Prosecution concedes that he is unable to produce exact (nor indeed approximate) figures by calculation of the pressures generated by the thermally-induced expanditudiness and contractionicity of the liners, and instead provides evidence by way of analogous models (the classic "fire sprinklers, single malts and drawing-pins" manoeuvre).
I think that sums it up so far?
"It might be a bit better to tune to one of my fiddle's open strings, like A, rather than asking me for an F#." - Martin Milner-
Terry McGee
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Not really a satisfactory place to leave matters, as the health of peoples' flutes depends on them understanding the forces that imperil them, and the steps that they might take to minimise those risks. If we cannot agree which are those forces, and which are those remedies, we cannot assist people to make right decisions.GaryKelly wrote:I think that sums it up so far?
I've identified a number of URLs which support my arguments that humidity is the primary issue in wood shrinkage. Perhaps you can identify some URLs that support your claim that temperature is the culprit.
Terry
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Terry McGee
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The traditional way to cook a Cockatoo is to boil it for several days, along with a large stone. When the stone is tender, you throw the cockatoo away and eat the stone.andrewK wrote:I have wondered what you eat down there since you said the cockattoos are too tough. ( but you did say "and out again ?).
I understand that the larger lizards are good eating. Assuming that you are fussy in OZ !
We're inundated by cockatoos at the moment, probably because of the continuing dry weather. They are big birds, totally white with a yellow crest, almost the size of a small chicken, but with a big wingspan and an incredibly raucous voice. They play havoc with our cat, dropping silently out of the sky in a power dive behind her, opening the big wings like a parachure a few feet from the ground and letting out a bloodcurdling screech. The Prozac niblets are helping.
Larger lizards are apparently excellent eating, unfortunately the little skinks that run under the door of the workshop and hide among the case timbers are about the size of a c key. But fast! If you do manage to catch them, they drop their tails, which wriggle around attracting attention while the skink makes a break for it.
Terry
I hope I am allowed to introduce some more evidence at this late stage of the trial.
The migration of water vapor, and consequent stresses and dimensional changes can happen much more quickly than the discussion implies. Though the time to reach equilibrium may be relatively long, the changes begin as soon as the wood is exposed to a different humidity level.
Here is the method I use to attach rings to flute sections.
First I machine the ring seating (on the wood joint) to a diameter which is 0.003" (0.075mm) larger than the inside diameter of the ring. The I put the wood sections into the kitchen oven (electric) at a temperature setting just below "warm". I monitor temperature and humidity inside the oven using an Oregon Scientific thermometer/hygrometer with remote sensor. Temperature is 110 to 120 degrees F (43 to 49 Celsius) and relative humidity at 10% to 20%, depending on how dry the ambient air is. After one hour I take the sections out. Usually the rings are now a firm push fit. Sometimes they are too tight, then I pop the piece back in the oven for another 20 minutes or so, which usually does the trick.
I glue the rings on with a polyurethane adhesive (gorilla glue) preceded by an acetone wipe of the metal and the wood, and a wipe of the wood with a damp cloth, since gorilla glue is moisture activated.
Up to now, I have not reduced any flutes to charcoal, though I have started putting a "flutes in oven" sign on the temperature control, just in case Marlene decides to pre-heat it to 400 degrees to bake a cake.
Dave Copley
Loveland, Ohio
The migration of water vapor, and consequent stresses and dimensional changes can happen much more quickly than the discussion implies. Though the time to reach equilibrium may be relatively long, the changes begin as soon as the wood is exposed to a different humidity level.
Here is the method I use to attach rings to flute sections.
First I machine the ring seating (on the wood joint) to a diameter which is 0.003" (0.075mm) larger than the inside diameter of the ring. The I put the wood sections into the kitchen oven (electric) at a temperature setting just below "warm". I monitor temperature and humidity inside the oven using an Oregon Scientific thermometer/hygrometer with remote sensor. Temperature is 110 to 120 degrees F (43 to 49 Celsius) and relative humidity at 10% to 20%, depending on how dry the ambient air is. After one hour I take the sections out. Usually the rings are now a firm push fit. Sometimes they are too tight, then I pop the piece back in the oven for another 20 minutes or so, which usually does the trick.
I glue the rings on with a polyurethane adhesive (gorilla glue) preceded by an acetone wipe of the metal and the wood, and a wipe of the wood with a damp cloth, since gorilla glue is moisture activated.
Up to now, I have not reduced any flutes to charcoal, though I have started putting a "flutes in oven" sign on the temperature control, just in case Marlene decides to pre-heat it to 400 degrees to bake a cake.
Dave Copley
Loveland, Ohio
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GaryKelly
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I haven't 'left matters' Terry, I was just summarising 11 pages into one so we would be clear where we are in the proceedings. A summary isn't a conclusion, I was genuinely trying to be helpful, to both of us as well as to everyone else.Terry McGee wrote:Not really a satisfactory place to leave matters, as the health of peoples' flutes depends on them understanding the forces that imperil them, and the steps that they might take to minimise those risks. If we cannot agree which are those forces, and which are those remedies, we cannot assist people to make right decisions.GaryKelly wrote:I think that sums it up so far?
I've identified a number of URLs which support my arguments that humidity is the primary issue in wood shrinkage. Perhaps you can identify some URLs that support your claim that temperature is the culprit.
Terry
I don't believe either of us are in a position to provide the magic bullet to people by which they may protect their flutes from this day forth. Storing a flute in a controlled environment (temperature and humidity) makes perfect intuitive sense and can do no harm, and of course swabbing out and oiling is something almost everyone agrees upon.
The Laws of Physics don't need URLs old chap.
But if you seriously don't believe that metal expands and contracts with changes in temperature, by all means have a look the wrecked railway tracks and broken sleepers caused by nothing more than a night/day temperature change: http://structures-www.cv.imperial.ac.uk/examples/
I do understand your argument (finally, as it has evolved somewhat since your original posts). I don't agree with it yet but can of course be persuaded as and when you reveal your methodology for peer review. It's strange though that you seem constantly to deny that temperature changes can (and do) cause catastrophic damage.
It would be wonderful if flutes were immune to temperature changes, and wonderful if liners didn't possess the properties that they do. It would be wonderful if the humidity theory is correct. Because then no flutes would ever crack again, for the 'solution' would be simple: humidification (which is what a lot of people are currently doing, though it seems that's no guarantee of protection). Humidification is much simpler, say, than makers changing their working practices or materials, or having to remove liners from old flutes and do a proper job of fitting them.
"It might be a bit better to tune to one of my fiddle's open strings, like A, rather than asking me for an F#." - Martin MilnerI have been looking again at old rings with machined in spurs inside which were hammered on to locate the ring. ( I have a Gerock and Wolf one before me now . Little spurs all round ) These produced cracks.
Similarly Monzani for example used to pin the rings in. Again cracks produced.
Just like splitting logs.
Though some idiot makers burred the tubes not all of them did.
Of course the two makers mentioned both screwed their short tubes in.
Shellac gave, I suspect a good bit of protection from movement & possibly some incidence of cracking.
Of course the two makers mentioned both screwed their short head / barrel tubes in. Rather better, except I am left wondering how to get them out !
Similarly Monzani for example used to pin the rings in. Again cracks produced.
Just like splitting logs.
Though some idiot makers burred the tubes not all of them did.
Of course the two makers mentioned both screwed their short tubes in.
Shellac gave, I suspect a good bit of protection from movement & possibly some incidence of cracking.
Of course the two makers mentioned both screwed their short head / barrel tubes in. Rather better, except I am left wondering how to get them out !
I am losing touch with all of this !
( When was I in touch ? ).
The headjoint / barrel which suffers most of the cracking is lined in many flutes. So if the lining is securely fixed to the wood ( shellaced in many cases, so an impervious edge ) is all the condensed breath just being sucked in the end of the cut fibres in the mouthhole? This can be superglued over,perhaps or a lovely little chimney fitted, perhaps attached to a lip plate.
I am surprised that Mr Rudall didn't have a pot of tar to wipe round his endangered hole rendering the cut xylem/ phloem tubes or whatever secure !
In fact the ivory or mother of pearl bushes of Prowse, Wylde sometimes & the like would have done the barrier job.
( When was I in touch ? ).
The headjoint / barrel which suffers most of the cracking is lined in many flutes. So if the lining is securely fixed to the wood ( shellaced in many cases, so an impervious edge ) is all the condensed breath just being sucked in the end of the cut fibres in the mouthhole? This can be superglued over,perhaps or a lovely little chimney fitted, perhaps attached to a lip plate.
I am surprised that Mr Rudall didn't have a pot of tar to wipe round his endangered hole rendering the cut xylem/ phloem tubes or whatever secure !
In fact the ivory or mother of pearl bushes of Prowse, Wylde sometimes & the like would have done the barrier job.
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Jon C.
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- Location: San Diego
I wrote on the 2nd page:The reason the rings fall off at low humidity, is that the rings were put on at high humidity. I want to get a dehumidifier box to shrink the wood as much as possible before fitting the rings.
That sounds like a great technique for making sure thta the wood is at it's dryest /most shrunken state. Thanks for sharing that Dave. Also the rings are cold, so if we go by the "other" idea that the metal expands when heated it will give you a snugger fit, as the ring will later expand .0000004 or so inches... Maybe even freeze the rings in the freezer for that extra .0000001 reductuion.First I machine the ring seating (on the wood joint) to a diameter which is 0.003" (0.075mm) larger than the inside diameter of the ring. The I put the wood sections into the kitchen oven (electric) at a temperature setting just below "warm". I monitor temperature and humidity inside the oven using an Oregon Scientific thermometer/hygrometer with remote sensor. Temperature is 110 to 120 degrees F (43 to 49 Celsius) and relative humidity at 10% to 20%, depending on how dry the ambient air is. After one hour I take the sections out. Usually the rings are now a firm push fit. Sometimes they are too tight, then I pop the piece back in the oven for another 20 minutes or so, which usually does the trick.
I glue the rings on with a polyurethane adhesive (gorilla glue) preceded by an acetone wipe of the metal and the wood, and a wipe of the wood with a damp cloth, since gorilla glue is moisture activated.
Maybe the experts can explain how the wood can expand to the point of cracking a silver rings on the socket of an old cocuswood flute. Would this not be caused more from the wood expanding then the metal expanding?
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Jon C.
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Good point but, the rings were rolled sheet nickel silver and machined, the cracks were not on the solder joint and jagged. The flute had been stored in a oceanside invornment, all the brass corroded off and the keys were pitted. So that could have effected the rings.andrewK wrote:Perhaps the rings were cast rather than forged.
Over a time the crystal structure will degrade if cast.
Then there is the question of the quality of the soldered joint.
My point is that when you are dealing with these super-hard woods, the pressure that can develope when they expand would be directly proportionate to there hardness.
As a result of this thread, I just ordered some Delrin...
Jon
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tin tin
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Jon, I agree, this thread does make delrin seem rather appealing. On the other hand, I am rather attached to my baked (wood) Copley. Fortunately, unlike the chocolate chip cookies I like, the flute is not 'crispy on the outside, chewy on the inside.' One can only imagine the cracking potential in that case...
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Terry McGee
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Very good Dave, thanks for that account. It is perfectly consistent with my findings. Because the rate of moisture loss is proportional to the difference between the existing moisture level and what would be the final moisture level, the initial rate is very fast indeed. All the more so at the end of the piece, as the moisture has an easy way out through the end grain. My diameter measurements at end and middle of the test head shows that the ends change dimensions much faster than the middle. And you only have to drop 0.075mm for the rings to be fitable, so you only need the first little bit of the 0.4mm shrinkage I've been reporting. My first measurement was taken about 3 hours in, and the end had shrunken by just over what you report, but then mine was held at 20% while yours was 10 to 20%.dcopley wrote:I hope I am allowed to introduce some more evidence at this late stage of the trial.
The migration of water vapor, and consequent stresses and dimensional changes can happen much more quickly than the discussion implies. Though the time to reach equilibrium may be relatively long, the changes begin as soon as the wood is exposed to a different humidity level.
Here is the method I use to attach rings to flute sections.
First I machine the ring seating (on the wood joint) to a diameter which is 0.003" (0.075mm) larger than the inside diameter of the ring. The I put the wood sections into the kitchen oven (electric) at a temperature setting just below "warm". I monitor temperature and humidity inside the oven using an Oregon Scientific thermometer/hygrometer with remote sensor. Temperature is 110 to 120 degrees F (43 to 49 Celsius) and relative humidity at 10% to 20%, depending on how dry the ambient air is. After one hour I take the sections out. Usually the rings are now a firm push fit. Sometimes they are too tight, then I pop the piece back in the oven for another 20 minutes or so, which usually does the trick.
Uh, good plan! No, I don't believe the timber is at risk at 50 degrees C. The first sign of distress I'd espect to see is resin from the resin ducts starting to appear at the ends as tiny black dots. That starts to happen somewhere this side of 100C.Up to now, I have not reduced any flutes to charcoal, though I have started putting a "flutes in oven" sign on the temperature control, just in case Marlene decides to pre-heat it to 400 degrees to bake a cake.
Terry
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Jon C.
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Andrew, you can send me all your discarded Monzoni's and R&R's, I will take care of them for you. I will even give you a donation slip...andrewK wrote:All this talk of cracking makes me wonder if collecting is OK after all. If a flute cracks just sling it in the bin, and get the next one off the pile !
Jon