Puzzler: Oiling and Flute Dimensions

[woodfluter]

I think I can hear the groans already...hasn't there been enough on this topic?

Capsule Summary

I oil my flutes regularly. But very recently I treated two fine blackwood flutes with pure tung oil for the first time, and had to move the slides way out to bring them in tune. And they'e still that way. Help me figure out what is going on here, if you please. It may be of interest.

Background

My routine is to apply almond oil to the bores of these flutes every 2-3 months, leave it on 15-30 minutes before swabbing off, leaving just enough for a visible sheen. I swab dry when playing with a bit of paper towel the first few times afterward to keep from gunking up my silks. Then back to normal. About 2-3 times per year, I substitute raw linseed oil for the almond - otherwise the same. This is raw oil with no additives whatsoever.

I've been doing this with the McGee Rudall Perfected for exactly 10 years, and with the Olwell Pratten model for almost 3 years. These are six-key flutes. The tuning slide on each of these was pulled out farther initially, when I first got them, and over the space of (rough guess) less than six months they stabilized to the point that the slide position was very consistent. In fact, I took a bit of bamboo and shaved the sides off, the narrow to correspond with the McGee gap and the wide for the Olwell - as sort of a rough guide and starting position before fine-tuning to the others in the band.

Actually, I usually just eyeballed it, but periodically I'd check and confirm that this was pretty much the way things stood. I don't recall any significant changes after the usual oiling routine. If there were any, they certainly weren't very evident.

Enter Tung, the China Tree

Hearing that tung oil was more water repellent than linseed, I tried that out on a rosewood Eb flute with some apparent success and no harm. Didn't check tuning. Then treated the bore of my blackwood Healy F flute. Seemed fine. Did check tuning but no apparent change there. (But shorter flutes are a bit more sensitive to and need more embouchure coaxing, so I could have missed something.)

On March 11, I oiled the McGee and Olwell with tung oil for the first time. Specifics are: Behlen pure tung oil, no additives or drying agents added, recommended on can that excess oil be wiped off after 15 minutes, and I left it on for 15-20 minutes in each case. Wiped off very thoroughly.

Left flutes alone until 3/13 rehearsal, when noted that I had to pull out the slide on the Olwell by a seemingly ridiculous amount to tune to piano and fiddler. When got home, checked it against a chromatic tuner and sure enough, it needed that to come into tune. Checked both the McGee and Olwell on 3/15 - the same story for both! Now I had the bamboo guide to use for a comparison, and calipers handy too. So....

Before Tung oiling, showing the wee bamboo guide. Olwell above, McGee below.


After Tung oiling, brought into tune.


____________Olwell slide_____McGee slide
Originally: _____7.9___________5.0 mm
Post Tung:____10.6___________8.8 mm

I played the McGee for a three-hour dance, plus warm-up for an hour beforehand, on 3/16. Well, playing didn't seem to make any difference. I checked both flutes late that night, and again tonight (3/18) and the slide positions remain the same as above, within reasonable tolerances (actually getting about 11mm and 9mm now). For reference, I checked the McGee at the former slide position and it's a tad over 20 cents sharp. Yes, my tuner (actually two of them) is set to A=440, yes my embouchure and headjoint positioning are consistent.

So What Happened?

One line of conventional wisdom is that grenadilla is too dense and too oily to absorb any significant amount of water vapor in any event, and the oil just keeps the few microns at the surface from soaking up pooled condensate. And makes the bore smoother. For a different view, taking into account heartwood and quartersawn billets, see this: http://www.naylors-woodwind-repair.com/Grenadilla.htm

Naylor includes wooden Boehm flutes in this analysis, but focuses mostly on other woodwinds. He says that instruments tend to go flat over time in any climate. That would mean shortening the tuning slide to compensate. After his fairly radical vegetable oil soaking treatment, he claims they return to former dimensions (usually) and can be played again with standard barrel length on clarinets and regular reeds on oboes.

He also notes that instruments that are dry, or have had saliva damage, tend to go flat (bore shrinkage). Both of my flutes have been played very regularly, and the climate isn't dry, and they're kept in cases, so dryness isn't the culprit. I swab a lot during play, and don't exactly spit into it (and also the Olwell has a full headjoint liner) so I wouldn't think saliva would be the guilty party...but who knows?

Current Best Guess

This runs counter to the thinking of most folks, but I have reason from another experience and measurements with keyless sections to suspect that grenadilla does in fact absorb a good deal of moisture, and not just at the surface. Not necessarily in milligrams of water, but in relation to the wood structure - enough to affect dimensions. More radically, I think that oil might be able to actually displace moisture. But in this case, the flutes were acting as though they were dry - gone flat. And now I'm starting to suspect that there's something special about tung oil. It's supposed to be a hardening oil, for goodness sake. It shouldn't be penetrating far. But something made a significant change here, not seen with other oils.

Any hypotheses gratefully welcomed...

- Bill

[Casey Burns]

Tung Oil is a drying oil with a fairly rapid rate of polymerization. You can test this by applying a small amount to a paper towel, and letting this sit overnight. Preferably in a metal container should the polymerization be rapid enough to generate heat for spontaneous combustion. The oil will appear to have hardened - the area where it was applied will feel stiff.

Pitch is controlled by many factors, down to the actual "tooth" or texture of the finished bore surface. What may appear smooth to some is actually full of texture when looked at microscopically. Increasing the coarseness of this texture increases the simple friction at the boundary layer which lowers the pitch. This arises from moisture which can raise the grain some. Shrinking may also lower pitch, but usually one can restore the pitch of a flat playing flute by resurfacing the bore without having to re-ream the bore.

If the Tung Oil is of the kind that rapidly polymerizes, it may be that the bore has been essentially made smoother by the application of tung oil. Essentially you have varnished your bore with a varnish, but not oiled the wood itself in the correct bore oil sense.

The Tung Oil may be impervious to liquid water. However, I am not so sure about water vapor. If not, this will penetrate through the tung oil and get into the wood. Oiling's purpose is to keep the wood supple in the face of moisture however applied. Without bore oil, wood will get brittle soon from the drying and wetting cycles. The application of tung oil will probably prevent any bore oil from penetrating into the wood if its needed. So this could potentially be a problem. I did a quick google search for "water vapor permeability Tung Oil" and found that a cured Tung Oil film is most likely permeable by water vapor.

If so, correcting this would involve sending the flutes back to their makers and having them simply resurface the bores, to remove the Tung Oil varnish.

Casey

[LorenzoFlute]

Isn't 20 minutes too little time for all this Casey? I mean, the layer of polimerized tung oil must be really thin, maybe all he needs to do is to clean the bore with some denaturated alcohol...?

[Terry McGee]

Hmmm, I'm not sure I'd go so far as assuming we have a problem here that needs fixing. I think we have to at first confirm we have a phenomenon at all (i.e. that Bill isn't being fooled by something else coincident with his trying a new oil), and also to try to quantify that phenomenon, so that we can see whether a proposed explanation is likely to be in the ballpark or not.

(Interesting that an Irish-Australian should lapse into talking ballparks, when we have footy ovals, cricket pitches or playing fields, but no ballparks.)

The answer to the first question is probably to wait awhile and see if the change rectifies itself. It's only a week since Bill oiled the flutes. Tung oil is slow drying (although then almond oil I think is not drying at all?). Let's see what the next few weeks brings.

Secondly, how big a change would we need to induce to produce the changes Bill is seeing? The answer would be whatever is needed to restore the original tuning situation. I tried a simple test of introducing a wire up the bore to simulate a reduction in bore diameter. A thin wire, just over 1mm, produced no measurable change. A 1/8" (3.2mm) rod produced a small but not significant pitch change. A problem here is that the rod or wire is cylindrical, while the bore is conical, so really I need to use a conical wire or rod, or approximate it with short lengths of cylindrical wire or rod end-to-end. Anyway, as a first approximation it didn't do much. Even given the shortcomings of the experiment, it doesn't encourage us to expect small bore changes are going to result in measurable pitch changes.

I think let's wait a bit and be sure we aren't seeing some transitional or coincidental effect.

Terry

[Rob Sharer]

I am not buying this story at all.

First, unless your oil is "chunky style", with loads of actual linseeds in it, I cannot imagine that you could build up enough of a film in one application to produce such a measurable change in tuning. No way.

Second, there are too many uncontrolled variables to make this a scientific analysis. I am particularly referring to the largest component in the system, i.e. the flute driver. We as fluthers have so much control over tuning with our embouchures that any test like this is automatically suspect.

If you could control for temperature and humidity, test against a reliable tuner only, and use some sort of precision flute-blower that would maintain a consistent angle of incidence against the blowing edge, THEN you might be able to do some science on this question. Even then, I am reasonably certain that something besides the results of a single oiling session is at work here.


Rob

[kkrell]

I'm going to make a wild guess here that the dimensions of the flute are not changing.

The flute now plays easier, with a lower air requirement, due to the particular oil treatment. Maybe it's leaking less, so there is less struggle. The player is able to use air more efficiently, and is thus blowing sharper until they can adjust to the new playing characteristics of the (improved?) flute. Currently, to correct pitch is finding it necessary to lengthen (flatten) the flute by pulling out the slide.

[woodfluter]

Thanks everyone, for your comments and speculations thus far.

To clear up a few things in random order:

"Hmmm, I'm not sure I'd go so far as assuming we have a problem here that needs fixing."

Exactly right. I might not have made this clear enough, but the tung oil treatment effectively brought the tuning slide position of both flutes, the one I'd been playing for 10 years and the one only 3 years old, to something close to the position needed when I received them. In other words, where the slides were before I "broke them in". The internal tuning is fine, including across registers. The mystery here is (a) why didn't almond oil and linseed do this, and (b) what's the mechanism?

"The Tung Oil may be impervious to liquid water. However, I am not so sure about water vapor."

I did a good bit of research before using this stuff. It is pervious to water vapor, seen as a downside for furniture finishers, good from our standpoint. I agree, want to allow moisture exchange.

"Tung Oil is a drying oil with a fairly rapid rate of polymerization. You can test this by applying a small amount to a paper towel, and letting this sit overnight....The oil will appear to have hardened - "

That's what I'd have thought, because linseed will do that. But I last used the tung oil two days ago, for a second coat on the rosewood Eb, and some was spilled on the top of the can. I checked just now, and it is very slightly more viscous but not hardened or dried at all, or even stiff. It's still like...well, like motor oil in consistency. Go figure.

"If the Tung Oil is of the kind that rapidly polymerizes, it may be that the bore has been essentially made smoother by the application of tung oil. Essentially you have varnished your bore with a varnish, but not oiled the wood itself in the correct bore oil sense."

Nope. Pure tung oil, boldly advertising no additives whatsoever. The surface of the flutes I've treated look *exactly* like they would after treatment with my usual oils. Not varnished at all, surface just glistens a little more than before treatment, but not a whole lot.

"Pitch is controlled by many factors, down to the actual "tooth" or texture of the finished bore surface. What may appear smooth to some is actually full of texture when looked at microscopically."

I've heard this many times, and you all know far more than I, but this seems to be slightly counterbalanced by what I see when I disassemble my flutes and look down the bore. Depends on weather, but typically I can play for only a few minutes, pull off the head joint, look down and see the surface completely coated with tiny droplets of condensate. Agreed, they can move more than rough wood, but essentially the innards of my flutes (including silver one) are never smooth while in use.

"First, unless your oil is "chunky style", with loads of actual linseeds in it, I cannot imagine that you could build up enough of a film in one application to produce such a measurable change in tuning."

I totally agree. This can't have anything to do with films on the surface. There isn't any visible film anyway. Has to be something internal to the wood.

"Second, there are too many uncontrolled variables to make this a scientific analysis. I am particularly referring to the largest component in the system, i.e. the flute driver."

Believe me, I know. That's the first thing I'd suspect if reading this casually. But here I've been playing these things for years with the slides set in one position with very little variation, then I use a new oil, and now the slides require a different position - for the next 5 days so far. Including three hours of steady playing for a dance. Agreed, not a scientific demonstration of anything, but I'm very sure it's not all in my head, or mouth.

"The flute now plays easier, with a lower air requirement, due to the particular oil treatment. The player is able to use air more efficiently, and is thus blowing sharper until they can adjust to the new playing characteristics..."

Kevin, this sounds very plausible and I can't dismiss it entirely. But the flutes don't seem to be playing more easily and there wasn't a struggle to begin with. One rough measure of efficiently that I use is how many bars of a tune, with a mix of high and low notes, I can play at 116-120 with a single tank of air. The A part of Walker Street is a reasonable test. Typically, that's 6 bars without effort, and really at the bottom of my lungs if I push for 8. I just tried that again with the Olwell, and there's no change in that.

Hope folks didn't misunderstand - I don't perceive any problem here, at least not yet. The flutes aren't playing worse, or out of tune; and they may be closer to the way the makers intended them! But there's something interesting going and I'd like to figure it out.

- Bill

[MTGuru]

unless your oil is "chunky style"

That image is my smile of the day.

[woodfluter]

unless your oil is "chunky style"

That image is my smile of the day.

I have to draw the line somewhere...no peanut butter inside my flute!

Standing joke by a fiddler I know is that he offers chewing gum to everyone before we play, then says "flute player can't have any, he'll blow chunks!"

[woodfluter]

Minor update...

Both blackwood flutes are still the same. Checked them tonight. Still require the same increased slide pullout of 11mm and 9mm approx. for Olwell and McGee respectively.

I mentioned tung oiling a keyless rosewood Eb, as an initial test. It's a Ralph Sweet flute I got many years back, and in general I think the Sweetheart flutes are a very mixed bag, but this one was exceptional - it sang. I did some tweaking to toneholes and a little to the embouchure hole to give it a tad more undercut, polished the bore, and it played even better. But was initially sharp - before I did anything to it. I remember using an O-ring on the inside of the socket to fill the gap and bring it to fairly accurate tuning. A couple of years on (I wasn't at all diligent in oiling this one) it was at pitch without the O-ring, so I removed that.

I checked it against the tuner today, and it's about 20 cents sharp. I put a thick-wall O-ring into the socket and it's at pitch.

So now I'm suspecting that the oiling routine I'd been using on the blackwood flutes wasn't sufficient. Maybe didn't leave the Almond oil in place long enough to absorb? And for some unknown reason, the Tung oil penetrates faster? Even in 20 minutes?

By the way, the tung oil spilled on top of the can is still...oily. Some residue around the cap threads is gummy. So I think we can say that it polymerizes in contact with the air somewhere between 4 days and 10 days. The Behlen stuff does anyway.

I cited something by Naylor in the first post. Here's a more extensive article from Woodwind Quarterly, 1994 - it's a Word document so you have to download it to read it: http://www.google.com/url?sa=t&rct=j&q= ... PVO_yOLvGQ

There's a lot to digest here, but among other things he's advocating letting almond oil sit in the bore for 12-16 hours before swabbing out excess. That's way far off my routine. But much of what he's saying fits with my flutes going flat over time, supposing that I just wasn't getting enough oil into them.

I have a (minor) gig Tuesday night, but I'm going to apply almond oil to both flutes now and let that sit for 12 hours. It may retard the polymerization of the tung...don't know, but can't imagine that it could hurt. Then see how things stand.

[LorenzoFlute]

I usually oil with almond oil in the afternoon and keep it there till morning. 20 minutes sounded to me like a waste of time..

[Rob Sharer]

Minor update...

Both blackwood flutes are still the same. Checked them tonight. Still require the same increased slide pullout of 11mm and 9mm approx. for Olwell and McGee respectively.

They require that slide pullout for how you're playing today.

I can push the slide all the way in on my Olwell Pratten and still push it all the way down to the key of C (don't ask about the tone!), so great is the control a flute player has over pitch. Measuring the slide isn't measuring anything.


Rob

[jemtheflute]

Oiling, schmoiling! Lay off 'em! Once a flute is well played in, IMO & E 3-4 times a year is quite sufficient, whatever you use.

[woodfluter]

OK, time for an update.

It's now been 13 days since tung oil treatment.
Change in slide positions was noted 4 days in.
Slide positions remain at their changed position.

(So the difference was noted 4 days after and remains 13 days after.)

Nope, not just the way I play it today; but for the last 10 days.
My slide position has been far more consistent that that.
Everyone's habits may differ. I can blow flat or sharp too.
I usually eyeball it initially, adjust by lipping, then shift the slide when I get a chance.
There's a fairly limited range where I get the best tone, if in tune.
So I know this is real.

No pressure, but did anyone read the linked articles?
Is this guy totally wrong about changes in tuning with oiling?

Othannen said that 20 minutes of almond oiling seems like a waste of time.
I think he's very right.
I was supposing the effect was just on the surface, and a little residue would be left anyway.
Now I'm way less sure of that. And maybe I let these flutes dry out a bit.

Top of the tung oil can:
The film left from spilling is now just a little viscous. More so than motor oil.
Also no yellowing. This is different from raw linseed and not what I expected.
I think the gummy stuff on the threads of the cap and spout was from initial filling.
So this stuff is not polymerizing fast. Probably slower in the wood grain than on the can top.

I'm also having second thoughts about what "breaking in the flute" means.
It might not be a good thing, if changes are involved!

[Terry McGee]

No pressure, but did anyone read the linked articles?
Is this guy totally wrong about changes in tuning with oiling?

My problem with these articles is that he makes many assertions and claims, but doesn't seem to back them up with experimental evidence. He may well have proofs up his sleeve, but if he wants to be believed he has to convince us.

To take a simple example - his Simple Experiment for Skeptics in which he suggests applying olive oil to the crowned side of a warped kitchen chopping board. Most skeptics aren't going to bother, because it's a too-different situation from the one we are concerned with. Materials, shapes, treatment are all different. Even if a dramatic change occurs, what does it tell us about clarinets? And what would happen if you had two chopping boards and applied motor oil to the other? (Other than you would probably throw at least one of them away later!) Would that do the same thing, or less or more. And would that tell us anything?

Unfortunately, the clarinet companies, who obviously hold the opposing view, that a thin petroleum based oil is best, don't do themselves any favours either. I've seen no evidence offered that this is the way to go. I'm more inclined to believe it because they have more to lose, but that's not a comforting way to have to make decisions!

So, it seems, as usual, if we want to know, we have to find out ourselves. You've made a useful start - identifying what you think is a phenomenon. Respondents who think you are stark-raving-mad are also fulfilling an important role - questioning. The next step is duplication - can someone else do the same thing and confirm the outcome? If we can prove we have a repeatable phenomenon, it shouldn't be too hard to work out what's going on and whether it's a good thing or not.

I do plan with my next flute repair to measure the tuning before oiling, then after. And the weight and some dimensions. This flute has hardly been played at all in recent times. We may learn something.

Terry