© 2019 by Olwell Flutes (Matthew Olwell, Editor, Photographer, & Webmaster)

  • Patrick Olwell

Many discussions of the different types of simple-system flutes currently played in Irish music mention tone-hole size in comparing flutes, but the usefulness of terms like “small holes” or “medium holes” is limited without actual measurements. Hoping that it might prove useful to players and those interested in the similarities or differences between various flutes, here is some information about our in-house system of classification...

Right-Hand Tone Holes, Blackwod Pratten

We use the measurement of the #4 hole (which corresponds to the right hand index finger for a right-handed player) as the main reference point that describes the “size” of a flute—this corresponds with our Pratten, Nicholson, and Rudall-Rose models. The reason I started using the #4 hole is that I use the G and D scales to lay out the tonal “map” of the flute, and I use these triads in the first round of tuning each instrument as it is being made. (Note that we’re talking here about concert flutes in the key of D, but the same general rules and nomenclature apply to flutes in other keys.) I tend to think of the first octave G (and sometimes also the low D) as “home base” and G is usually the first note that I check using a tuner. Although somewhat a quirk of our making process, this system may also be related to the general layout of a six-holed transverse flute, as small D piccolos are called G flutes in China, and in India this note is also often the tonic. Another factor is the likelihood of a given note playing more true than another: the G-position note on simple-system flutes is often more dependable than the A, which tends to be unpredictable on 19th century London flutes as well as some others.

There is also the question of tone and feel. On simple-system flutes, the size of finger holes on one instrument relative to another affects the “voice” or character of tone that the flute will have. To my ear, a flute with smaller holes feels a bit more veiled, subdued, or not as “open” as one with larger holes (complicated by the fact that the bore and embouchure also have a significant impact on these qualities). This is important in choosing the sound and feel you prefer as a player.

Anyhow, in the interest of reducing the overall confusion regarding what constitutes small, medium, or large holes, here is our yardstick or classification system, which corresponds to our Pratten and Nicholson models etc...

#4 hole:

  • 6.0–6.4mm (Smallest) Baroque and early Classical and Romantic period flutes.

  • 7.0mm (Smaller) Romantic period flutes, smallest holes on Rudall-Rose.

  • 8.0mm (Small) London-based flutemakers manufactured many of their flutes like this, even after Nicholson’s revolution.

  • 9.0mm (Medium) Nicholson Flute. The third photo below shows a Rudall-Rose flute and a T. Prowse flute that have almost identically-sized holes. Prowse was authorized to stamp his “C. Nicholson’s Improved” and it’s my understanding these measurements represent the large-holed version of his flutes that other maker’s copied.

  • 9.6-10mm (Large) Pratten Flutes.

There are of course exceptions to the above specs if we are talking about antique flutes, and the water is muddied by the fact that many English flutes fall somewhere between the above delineations (what do we call a flute with a #4 hole of 7.5mm or 8.5?), but at least this is a standardized nomenclature that we can employ to compare one flute to another with some level of precision.

We use this system to describe our own flutes, and on our price list the 8.0 is referred to as Small, the 9.0 mm is Medium, and the 9.6 is Large (we realize that a Baroque musician might call the 6.0mm “normal’ and the 9.0mm “gigantic.”) We don’t currently make a flute with anything smaller than the 8.0 above, as most of our customers are playing traditional music and want the more “open” sound. I do own many antique flutes (including two by Rudall-Rose) with smaller holes that I think have a beautiful tone.

If you want to know the specific measurements of your own flute, you can buy a plastic vernier caliper (plastic is good because you won’t risk scratching the flute) for about $20. This comes in handy if you want to make precise measurements.

I hope that this system of sizing will aid anyone who wants to compare flutes and gain some insight into the way that hole-size effects tone.



(Pictured above: French, 6.5mm, American, 7.0mm, and Rudall-Rose and T. Prowse, 9.0mm)

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  • Patrick Olwell

Updated: Mar 5, 2019

Those new to the wooden flute often have to navigate some confusing territory, as the design of the instruments is generally less standardized between makers than that of silver flutes or violins. This is particularly true when it comes to the specifications of the headjoint, and there are many choices and differing opinions as to what is best. Some players prefer a headjoint as much like those of the original 19th century Nicholson flutes as possible, which were fully-lined with brass tubing and featured a thinner wood head tube than the earlier London-made flutes. This thinner tube dimension means that the embouchure “chimney”—the measurement from the inside to the outside of the flute—is not as tall as on earlier flutes. While this makes for an amazing tone in the hands of a skilled player (part of the revolution Charles Nicholson helped to bring about), these flutes are not always as easy to play for someone with less experience, and a taller chimney seems to provide a consistent sound more easily. Also, the mouth-hole size (embouchure) changed during Nicholson’s time. In the 1820's they were usually smaller, measuring about 9×11mm but by the 1850's had grown to a size of approximately 10×12mm, which is closer to both the Boehm flute and the wooden flutes of today. While a millimeter may not sound like much change, it has a significant effect on the way it feels to play the flute.

Even more confusing is the discussion of fully-lined versus half-lined headjoints. All of the flutes crafted by English flute makers during the period from 1820-1880 (with the exception of Monzani) featured fully-lined heads, as part of the new flute sound that was becoming popular at this time was a more “metallic” or powerful projection. Everyone who heard Charles Nicholson play was astonished by the sound, and most players joined this new school—in addition to playing very loudly, Nicholson was able to produce a wide palette of tones and play expressively at quieter volume. In France meanwhile, the fully-lined headjoint did not become popular, and all headjoints were half-lined, with a two-piece metal tuning slide that did not extend up to the embouchure and left the upper part of the headjoint unlined. (Johann Joachim Quantz had said in his 1750 treatise on the flute that a lined head had been tried, but “rendered the sound harsh and disagreeable.”) French flutes also featured the earlier smaller fingerholes and consequently played with a lighter, less forceful tone. As a result of these variations in design, there were two different schools of playing during this period, and they were grounded in different aesthetics (American flutes, principally made in New York City, fell somewhere between the French and English designs).

Currently, we make both half-lined and fully-lined headjoints and find that the differences between them are slight but noticeable to some. Patrick prefers a fully-lined head for session playing, as he feels he gets more projection with less effort, but Aaron prefers his half-lined head and finds it is as loud or louder with less effort and with a lighter weight. Ultimately, the difference between the two flutes is small and difficult to quantify. (We are planning a test with a group of blindfolded players and a number of lined and unlined headjoints to see if it is really consistently possible to tell the difference... we'll let you know the results.)

Also confusing is the assertion made by some that a lined head will always crack, or crack more often as the wood will continue to shrink. In our experience this is not the case—a piece of blackwood is not like a black hole, continuing to shrink forever, but will only do so while losing moisture, and once fully-dried, becomes quite stable. It is true that gluing a metal tube into a cylinder of wood is a cockamamie design from an engineering standpoint (as the wood does expand and contract somewhat with changes in humidity, whereas the metal does not) but with reasonable care, problems can be minimized. You have to be careful traveling from wet to dry climates or vice versa (say, from Ireland to your home in the desert near Phoenix) but an all-wood flute with no metal tubing can also crack under these conditions. Please see our “Care and Feeding” post for more information about humidity and its effect on wooden flutes. The early advertisements from the 19th century for the then-new lined heads maintained they wouldn't crack, as the lining made it more difficult for moisture to be absorbed into the wood of the headjoint, so it’s easy to see why there is so much confusion on this point.

Ultimately, choosing a headjoint comes down to the inclination of the player, and your best bet is to try as many as possible and decide what you prefer.

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  • Patrick Olwell

Updated: Mar 3, 2019

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. 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 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 a wet climate, swab the flute out after playing with a plastic cleaning rod and a lint-free cloth (silk is preferable) to prevent too much moisture from remaining on the inner surface of the bore.

Keep flutes in an airtight plastic container with a hygromter to monitor humidity

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.


Oil the bore of your flute regularly with a thin coat of organic oil. In very dry climates and with a brand new flute you will have to 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.

Buildup on the inside of holes can be cleaned using a Q-tip and rubbing alcohol

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.

Protect pads with plastic wrap when oiling

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.


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 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.