Bowed Instruments & Relative Humidity

Opinions vary about whether to humidify bowed instruments. Some people find that their instrument sounds better if it is kept humidified, and some believe that humidifying will keep an instrument from cracking. If you choose to humidify for either reason, be very consistent and diligent about the process, or it is best not to do it at all.

If you choose to humidify your instrument with a case humidifier, or with a "snake" style humidifier that fits through the f-hole, it is very important that you make sure that it stays moist at all times. This requires saturating the sponge every day while also being careful that it is not so wet that it drips inside the instrument. Humidifying is an attempt to keep the instrument dimensionally stable. If you allow the sponge to dry out, then your efforts will be counterproductive.

Problems from humidity vary greatly from one instrument to the next, and many players will notice little or no change (entry-level beginner instruments, for example will generally not be noticeably affected.) An instrument that changes a great deal with the seasonal changes in relative humidity can have sound problems, structural problems, or playing problems that include the bridges on cellos and basses being too high or low due to the movement of the top as it absorbs and releases moisture (down in dry conditions, and up when humid.) Cellists might need two or more interchangeable bridges to compensate for string height changes, and bass players would need bridge adjusters for the same purpose.

For those who notice tonal changes, usually a periodic sound post adjustment (by someone who knows what they are doing!) will correct the sound problem. Dry winter air, for example can shrink the top and back causing them to tighten against the sound post and therefore not vibrate as freely as they should. On more sensitive instruments, minor sound post adjustments can make a big difference.

An instrument that is moved to a dry climate after living most of its life in a very humid one, sometimes needs to be opened up at the seams so that it can adjust for several weeks before re-gluing. With sensitive vintage instruments there can be more serious problems requiring extensive restoration work.

Better bowed instruments are constructed by gluing the top on with half strength violin makers glue, so that under stress the sensitive spruce top will separate from the rib instead of cracking. It is far less expensive to glue an open seam than to remove the top to fix a crack. So if a seam opens, consider that good news, but get it fixed right away.