Maintaining Your Instrument

Disclaimer

Please note that you should contact the manufacturer of your instrument for specific care instructions. Should you choose to implement any care procedure found on this page, you do so completely at your own risk. Some of the procedures on this page are experimental or theoretical.

Oils

It is generally recommended that you oil a wooden flute as part of its normal maintenance. Selecting the type of oil to use has been a hot topic for conversation, with various instrument makers and players adopting positions for or against various oils.

Kevin Krell submitted a link to an article by Raymond and Lee Dessy about the chemistry behind oiling woodwind instruments (from a site which focuses on recorders maintained by Nicholas S. Lander).

Also, here is an excellent overview of available oils that was contributed to the woodenflute email list by M. Dominic Ryan <ryanmd@mms.sbphrd.com>:

Greetings all,

Some time ago I inquired amongst several people as to the best oil for my flute.   The one loud concensus is *not* to use boiled linseed oil.  Beyond that there were various suggestions to use almond oil, raw linseed oil, and olive oil.

I happen to be a chemist and an occasional woodworker, though definitly not a hallowed flute-make. Nonetheless, from a finishing point of view I am now less enthusiastic about olive oil. What follows is an explantion of what I have learned so far. Warning, some chemistry is included, so if you already rolling your eyes, delete now. It is also a bit long. Nor am I the first person to post on this, so while I no longer have the names of those that preceded my post, my thanks to them for piquing my interest and providing some of the background below as well..

All the oils are essentially triglycerides, that is a fatty acid ester of glycerol. (If that doesn't mean anything to you hold on...) But there is quite a variation in what else is in there and in just what specific fatty acid is present. There are different ones and they have different properties. If the molecular structure is right the fatty acid will polymerize by forming chemical bonds between individual molecules of fatty
acid (crosslinking them together). This results in a hard polymer. The same chemical element that can cross link can also be oxidized by atomspheric oxygen. Vegetable oils, such as olive oil, corn oil, peanut oil (despite the nut name it appears to behave like a vegetable oil), all have a much greater susceptibility to oxidation. They also are essentially completely non-hardening, or only so slowly that one can find roman era hardened oil, but not within a couple of years.

All the oils will soak into the wood and provide protection against water by coating the fibers with a protective layer that slows down, but does not completely prevent, water from crossing into the cells of the plant materiel. The cells swell up, and the wood expands.

Once the oil has polymerized the rate of water crossing is significantly reduced and the oil is more permanently retained. Without crosslinking the oil is greatly more subject to mechanical removal. This includes rubbing, but *also* just the passing of moisture across the surface. Some oil is entrained, slowly, from truly non-hardening oil.

Mineral oils are quite different again. There is essentially no mechanism for air oxidation of mineral oil (at room temperature, 500 degrees is another matter). Nor is there a possibility to crosslink. They have a very different chemical structure and are called hydrocarbons. Hydrocarbons derive differences in physical properties by having a different length of molecular chain. Volatile ones are short chains, i.e. gasoline to kerosene, and non-volatile ones are long, i.e. mineral oil to engine oil to tar.

The vegetable/nut oils have different properties not so much because of different *lengths* of molecular structure, but because of different chemical bonding patterns of molecules that are very nearly the same length. The lack of a route to oxidation makes mineral oils very stable, but non-digestible by humans, and even toxic.

Thus it seems that olive oil will protect from moisture to an extent, but it will require quite frequent reapplication. I may also possibly suffer from oxidation to produce rancid oil components but that has not apparently been a problem people have talked about. I suspect that it is because the "rancid" component of oxidised vegetable oils is somewhat more volatile and never noticed since there is only a small amount of oil in the wood anyway. But, it is perhaps an additional route to loss of oil over time.

The nut-oils, which includes seed oils, are naturally prone to polymerization over time. This is why they protect more. The hardening seems to take months to finish. This gives a chance to have a very thin and well distrubuted coating. However, in the furniture industry there is no time to do this and chemical polymerization agents are added to speed up the polymerizing process. These are usually toxic. Some of that happens naturally upon boiling the oil. The end result is that the oil will harden *MUCH* faster. In the case of linseed oil, boiled linseed oil hardens faster, but incompletely except over a very long time as well. It tends to get gummy because of the nature of the crosslinked structure.   So, "dryers" are added to crosslink more completely the oils. I suspect that if it were not for wanting to put your lips on the finish for long periods at shot a hardened wood finish might be ok. But there would be the additional difficulty of getting at the inner surfaces to rub them down as part of the finishing process for that sort of finish.

Even a well hardened oil will not provide a complete barrier. To do that would require one of a few possible finishes that completely envelop the wood. Poylurethane will do that and so will acrylic, but polyurethane can be applied in quite thin layers which is what is needed for good curing and hardening. Any flute makers willing to take a flyer on a polyurethane coating? If done well it might even be stable in Winnepeg at 7% humidity. I think you would have to immerse the flute and then perhaps gently spin it on a string to force off the excess. I would estimate that about 5 layers might provide a good water proofing. I would also use extra hardening agent in the urethane. One could use the newer non-solvent urethane finishes.

Lastly, I would really love to be corrected on any of this I may have misunderstood if it contradicts what your experiences are. I am trying to put this into a chemical context. References to additional information would be ideal.

Here is an extract from a response to Dominic's email sent by Terry McGee:

I tried polyurethane a long time ago (plain old commercial goop) and found it ineffectual. I got better results from Watco Danish Oil (2 coats) but not good enough. The commercial bore oil is much better than either of these or vegetable oil.

Humidity

It is generally agreed that changes in humidity and/or temperature are potential causes for cracks in wooden flutes. Rod Cameron <rcameron@mcn.org> contributed the following email message to the earlyflute email list:

I would think that one of the worst things you could do to a wooden flute is put a humidifier inside the bore. Flutes crack generally as a result of moisture being introduced too quickly into the bore of the flute by the player's breath while the outside of the instrument remains relatively dry, or very dry in the case of low humidity winters. The cracking is the result of the inside wanting to expand because it is moist, and the outside wanting to stay the same. This produces what is called a 'hoop stress'. Ideally what we want is a condition whereby the moisture can rapidly and evenly permeate throughout the cross-section of the wooden tube so that the whole body expands at the same rate and hence no hoop stress is set up. Once the flute is 'waterlogged', so to speak, it should be better able to handle long playing sessions. This is why makers recommend a careful playing in period of say...10 minutes a day morning and afternoon, increasing by five minutes each day. This allows more time for the injections of moisture from the player's breath in the bore to permeate out throughout the cross-section to an even result. In dry weather conditions, a flute left around the room while it is not played will rapidly lose ground in this process.

I recommend humidifiers on the outside of the flute, not the inside. I do not see any need to buy special cello humidifiers, etc., when all you are getting is something that holds a little moisture. For dry conditions, put your flute back into its soft case and put the soft case into a plastic bag within which is a small, damp cloth. This ensures that the flute lives its life in a controlled reasonably humid environment. The precious moisture added in small doses by sticking to the 'play in' schedule does not then evaporate but instead permeates evenly until a state of 'waterlogged' flute results. By all means swab the flute out after playing, otherwise the wood will think it is still being played in a long session as it sits in its case trying to absorb the droplets clinging to the bore. I know that it seems undignified to think about the wood flute as needing to be waterlogged, but that is the case with a fully played-in flute....what do you think is happening to all of that moisture from your breath? You will know that you are overdoing the damp cloth routine if you end up with a mold in the bore, so a little goes a long way. Those wanting to know more may put a small humidity meter in the plastic bag. Those who are even more curious will weigh their flute when it is new and dry and graph the increase in weight until it is 'played in'...noting that weight. In my experience, quite a few professional players crack their flutes by picking up a flute that has been idle for some time and then going to a long rehearsal session on the assumption that the flute is not new, has been played lots in the past, and so must be in a constant played-in condition. Wrong. Flutes loose their moisture quite fast...again a daily weighing will reveal this. If you absolutely have to play a long session on a dry flute no matter what the risk, it might be worth sponging it down on the outside regularly as you play....not the best treatment for the wood surface, but it allows moisture to enter from the outside as it enters on the inside from playing, and to a degree this lowers the hoop stress. If you already know the weight of your flute when it is in a thoroughly played-in state, then simply putting it on the weigh scale will tell you how dry it has become, and hence whether you need to again go slowly.

Almost everyone who cracks a flute wants to put the blame on a faulty piece of wood. However flutes can be subjected, wittingly and unwittingly, to fast changes of humidity and temperature with serious results.

In the particular case of later flutes with metal lined headjoints, this is almost an accident waiting to happen as the metal bore will not yield inwards if and when the wooden body wants to shrink around it due to experiencing dryness. I would be inclined to roll the metal lined headjoint in a very slightly dampened cloth during dangerously dry winter months. Remember also that in olden times flutes did not travel faster than a walking horse, and now many expect to play today in London and tomorrow in dry Madrid, even after the punishing low pressure journey on an aircraft.

Please do not regard the above paragraphs as gospel, and do not come back at me saying you followed my instructions and your flute cracked. I put these points forward only as talking points, and toss them out as lures over the still, early morning waters of the chat line, inviting you to rise to the fly and correct me where my thinking is faulty. I would be cautious about following any one person's advice, including my own, without first finding out if others with experience agree.



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