Humidity and Moisture
Our flutes are built to be as stable as possible; however, wood is an organic material and unlike metal or plastic, it will continue to respond to changes in moisture level with changes in shape. The wood of a brand-new flute has been carefully dried and conditioned in the workshop, and should be broken-in slowly to adjust to regular use. We recommend playing your new flute for no more than one hour a day for the first week, and gradually increasing after that.
The most important condition affecting the moisture content of a wooden flute is the relative humidity of the air around it, so it is a good idea to get a hygrometer and watch for changes in moisture wherever the flute is being kept. We think that the ideal range of humidity is 45-60% for a modern flute and 50-60% for an antique flute (these were often made from improperly-seasoned cocus wood and can be more sensitive). If perfectly constant humidity could be achieved outside and inside a flute it could be guaranteed never to swell, shrink, or crack—barring being sat on or dropped—but since constant humidity is functionally impossible outside of a laboratory, it is important to protect the flute from rapid changes in humidity.
A wooden flute can adjust to different climates relatively safely as long as it is allowed to do so slowly. In all cases, it should be protected against extremes of dryness and extreme humidity. A wooden headjoint with a metal tuning slide is an unusual case because the wood will shrink and swell while the metal will not. In extreme cases this could cause the wood that surrounds the metal to crack, so it should be looked after carefully in changing climates. For example, winters in the (Northern) United States can be extremely dry, while the same days in Ireland can be quite humid, even when it feels cold outside. Here are a few suggestions for protecting your flute while traveling between wet and dry climates or when seasonal changes occur:
Never force a tenon and socket together if they are swollen too tightly to fit easily (sockets are likely to crack if you do). When flute parts shrink from dryness and become loose, plumber’s Teflon tape is useful. It can be wrapped around the tenon in small increments and it will come off easily without damaging the cork.
In dry climates, keep the flute case sealed in a plastic bag or tub, or keep the flute in a tightly zippered nylon pouch. After short playing sessions, when just a few water droplets have formed inside the flute, simply shake it out rather than swabbing it so as to to help retain moisture.
In wet climates, make doubly sure to properly clean excess moisture from the bore after playing with a plastic or wooden cleaning rod and a piece of absorbent cloth to prevent too much moisture from remaining on the inner surface of the bore (more on that in a minute).
Bottom line? Try to prevent excess moisture from entering the flute in wet climates and leaving it in dry ones. Always allow the flute to warm up to room temperature before playing it. Be especially careful while playing outside in cold weather. Depending on where you live and/or where your flute is being kept, you may want to get a humidifier or a dehumidifier to adjust the humidity level of the air. Alternately, flutes can be kept in a plastic tub with a tight-fitting lid, a hygrometer, and a bit of damp sponge in a plastic bag perforated with a few holes to ensure that the proper level of humidity is maintained.
Cleaning
Even an instrument that's well-cared-for needs some extra love from time to time. It's always a good idea to take the sections of your flute apart immediately after playing and gently clean the inside of the bore with a soft piece of absorbent cloth threaded through the end of a cleaning rod to remove excess moisture and prevent the buildup of dirt, dust, and hardened oil (a cleaning rod made from plastic or wood is preferable to metal as the latter can scratch the bore). Make sure to insert the cleaning rod only from the wider end of the body and foot and avoid putting too much pressure on the tenons—one can also use a string-style cleaning rod as long as it's sized correctly. The tenons are the most fragile part of a wooden flute so do not use too much force and exercise caution when putting cleaning equipment through to avoid cracking them.
It’s a good idea to sight down the bore against a bright light when you clean the flute and notice any sign of buildup in the bore. If a flute is not cleaned regularly, residue from oil and dust can accumulate on this surface and/or on the key pads themselves.
If this happens, the gunk can often be removed with isopropyl alcohol, a rag, and some Q-tips for the key pads. The keys are removed by gently pulling the key pins out. This can often be done by hand, using a thumbnail to grab the curved end of the pin and pulling it gently, or by using fine-tipped needle-nose pliers. The key pad and seat can then be cleaned with alcohol and the key re-mounted. After cleaning but before remounting the keys, allow the instrument to dry and then lightly oil the bore with olive or almond oil (more on oiling below).
When remounting keys it can sometimes be difficult to align the hole in the key with the hole in the mount while the pin is being replaced. Be sure that the spring is lined up with key body and sight through the hole to ensure that the key is depressed the correct amount, lining the two holes up with each other while the pin is inserted.
If buildup in the bore is allowed to harden too much, it may be impossible to remove without using a properly-sized reamer and 800-1000 grit sandpaper. This is a tricky operation and should ideally be performed by the original maker or someone with a reamer that is sized exactly to the bore. In either case the work should be performed by an experienced flutemaker or repair person.
Oiling
Oil the bore of your flute regularly with a thin coat of organic oil. In very dry climates and with a brand new flute one should generally oil more often—maybe once a week at first and once a month thereafter, depending on how much you play and how much oil the wood absorbs. Sight down the bore with a bright light now and then to see if it is overly dry. You can put a small piece of oily, lint-free cloth on the end of a plastic cleaning rod to oil the bore and the thin edge of endgrain. Avoid getting oil on the tenons, corks, keys, pads, and metal tubing. If this happens, wipe the oil off immediately.
Try for a thin layer of oil that evenly coats the surface without so much volume as to run down the flute or get on these areas. You can also dab a little oil on the inside edges of the mouth hole with a Q-tip. If you notice dirt or other buildup inside the embouchure hole you can clean this off with a Q-tip and a drop of rubbing alcohol.
Never stick anything metal into your flute, as the bore will scratch easily.
If your flute has keys, you can avoid getting oil on the pads by either removing the keys themselves or by placing a small piece of plastic wrap under the key and wrapping it around the key cup.
The best oils for wooden flutes are olive and almond. Almond oil can oxidize and turn rancid if left to sit too long. The clear sweet almond oil sold in pharmacies in Ireland and Britain seems to be purified and less likely to go bad than the “cold pressed” almond oil found in health food stores. Adding a small amount of Vitamin E as an antioxidant will preserve the oil, as will refrigerating the container. Raw linseed oil (flaxseed oil) is sometimes used to treat new flutes, especially more porous woods like boxwood. It should not be used for follow-up maintenance, as it is a hardening oil and will become gummy inside the bore. Organic vegetable-based oils penetrate the wood fibers, displacing moisture that tends to enter the wood, and are therefore best for flute maintenance. Inorganic oils interact differently with wood fibers and seem not to work as well. There is an excellent article on the details and science of oil and blackwood (grenadilla) called “Grenadilla Wood and the Environment” by Larry Naylor in Woodwind Quarterly #6.
Temperature
The effect of temperature on wooden flutes is evident mostly in the intonation. A cold flute will play flatter, and will sharpen in pitch as it warms up (this is one reason a tuning slide is so useful.) Temperature also affects moisture absorption as a flute adjusts to being played, so take care to let your flute warm up to room temperature before playing it.
Be careful of excessive heat, which can damage a flute like any wooden instrument. Do not leave a flute in a hot car in summer. Even when the exterior temperature is not overly hot, a car left in direct sunlight can become hot enough inside to crack a flute. A good rule of thumb is "do not leave a flute in a situation in which you would not leave a child or pet."
Other Maintenance Suggestions
Apply cork grease as needed to cork tenons. In addition to being a lubricant, cork grease on the largest tenon in the headjoint will repel moisture and help to keep the cork and wood from swelling excessively.
The best way to deal with a sticky tuning slide is to clean both surfaces of the tubing with rubbing alcohol. We do not recommend the use of slide grease or other lubricants.
If your flute does crack, do not put oil or any kind of wax in the crack. Doing so will prevent the glue used in repair from adhering to the surface and penetrating the wood. Wrap a rubber band or string tightly around the crack and contact our workshop. Also, avoid taking a file or sandpaper to the flute to correct problems in the fit of tenons or keys. If the fit is not corrected by acclimation and attention to the points mentioned above, please contact us.
Great article!
A note: The link to the article “Grenadilla Wood and the Environment” no longer works (looks perhaps like a typo, missing the “f” at the end of the link.
Here is a working link: http://www.w7ekb.com/Personal/Pipes/Naylor1.pdf