October 2019
Temperature Effects on Wooden Instruments
by Jennifer Carpenter, ARS Board Member
I once had a student who admitted to me that they leave their wooden recorder in their car for months when they are traveling. After I picked my jaw up off the floor, I gently explained what can happen to their instruments in hot and/or cold environments.

Most of us are aware that wood expands in the heat and shrinks when it is cold. However, it’s not really the temperature that affects the wood, but rather the moisture in the air (and in the wood), which changes when the temperature rises and falls. These changes in moisture can create havoc on wooden instruments, especially wind instruments!

The moisture content of wood affects its density and strength, which, in turn, affects the acoustical and structural qualities of any wooden instrument. And because our instruments acquire even more moisture from being played, it is important to understand how moisture and humidity affect the instruments and how we should care for them .

What happens in the heat?
When the temperature rises, so does the humidity. Warm air has more space between the air particles, which allows the air to hold more water molecules. This humidity can settle into the wood, causing it to expand. If it expands too quickly, which can happen when left in a hot vehicle, the wood absorbs extra moisture from the air, causing it to swell, possibly leading to cracks. It is especially important to watch the tenons as they are the weakest part(s) of the instrument.

Some wooden recorders are permeated with a paraffin wax, which helps the wood retain its moisture content and repel outside sources of moisture. Unfortunately, when these instruments are subjected to extreme heat, the wax can melt, leaving quite the mess of oozing wax in and around your instrument, even blocking tone holes.
What happens in the cold?
During cold months, wood is more likely to stay the same size or slightly shrink because water cannot evaporate into cold air as easily as it can in warm air. The water molecules within your instrument shrink a bit as they cool down. However, if the wood becomes too cold (e.g. leaving it in the car during the winter months in cold environs where it stays below freezing) the water in the air and within the instrument will freeze and push the wood fibers apart. This can cause cracks in the wood.

If you find that your instrument has been exposed to cold temperatures, please allow it to return to room temperature gradually. Do not move it from your freezing car and put it next to a fireplace or heater. This can cause the wood to expand too quickly, leaving it susceptible to cracking or warping.
Do I need a humidifier or a dehumidifier?
Case study: I moved to arid Colorado after spending nearly my entire life in the sweltering humidity of the southeast. I quickly learned to oil my instruments to provide a moisture barrier and all but one of my instruments adjusted. However, I now have a voice flute that is nearing the shape of a crumhorn. Unfortunately, the warping affected the tenons, too. Could this have been avoided if I had stored it in a humidity-controlled room or case? Perhaps.
 When the air is cold, the water in the air condenses or freezes, leaving us with few water molecules. Humidifiers are helpful in cold, dry climates because they add moisture to the air by evaporation, either by heating, by increasing the surface area of the water, or by vibrating the water. There are humidifiers that are available for your instrument cases, your room, or even household humidifier systems.

If you live in a particularly humid climate and your home is not climate controlled (air conditioners largely act as dehumidifiers), you may want to consider a dehumidifier. A dehumidifier as akin to a vacuum cleaner: it sucks in air from your room, takes the water molecules out, and then blows it back out into the room again. Because most homes in humid climates have air conditioning, it is not as common to need a separate dehumidifier as a humidifier for your instruments. If you find that the humidity is too high during the winter months in more humid climates, run the air conditioner for a little while until the humidity levels are more stable.

Overall, it is best to avoid any big swings in humidity levels and keep your instruments in an environment with 40-50% humidity. You may find it worthwhile to purchase a good hygrometer with thermometer to track the levels. And whatever you do, don’t leave your instruments in your car!

For further reading, I suggest the following articles:

For tips from a previous ARS NOVA article by Barb Prescott on caring for your wooden recorders, click here .

For a scientific article about what happens with the moisture we blow into our instruments when we are playing, this is a fascinating piece that uses a baroque flute as its case study: https://www.conservationphysics.org/flute/flute.html
Jennifer Carpenter is a professional recorder player and teacher who lives in Colorado Springs, CO.
Do you enjoy our ARS NOVA emails?
Click here for our archive s , with articles on many topics ranging from how to care for your recorders, to useful apps, to scholarship and grant opportunities though ARS. If you've received this from a friend, sign up for your own monthly subscription using this link .
How to Join the ARS
Take advantage of our 1/2 price rate for first-time members! Get immediate access to all the information available on our website, as well as other member benefits including the quarterly American Recorder magazine.
USA: First year $25
Canada: First year $30