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 Humidity Control and Musical Instruments 
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Why Use a Humidity Control System?

If you live in or travel to environments which are extremely dry or moist, or which have sudden or extreme changes in temperature or humidity, you may consider installing some type of humidification system within your case.

On this page you will learn all about humid and dry conditions and how to control these conditions within your case, and when and if it is necessary to do so.

A system may be as basic as a hygrometer (sometimes combined with a thermometer) which helps you monitor the humidity (and temperature) within the case. A hygrometer does not control the conditions, it simply monitors and displays the conditions for you. In environments of extreme dampness or dryness, you may also consider adding desiccant to help remove excess moisture in the air, and/or a humidifier, which adds humidity to the air in dry conditions. Add these only if needed, depending on your relative environment.

A complete
humidification system
consists of a
hygrometer, a humidifier, and a

Depending on your
specific environment,
you may not need
a complete system.

How to control humidity in your case

If conditions are… Damp Conditions
Humidity more than 55%
Dry Conditions
Humidity less than 45%
What to do… Use desiccant to remove excess humidity.
Remove humidifier or do not recharge.
Remove desiccant from case.
Recharge humidifier.

Is it a Hygrometer or Hydrometer?

Some confusion exists on what to actually call the meter which monitors the humidity in your case. Is it called a hygrometer or a hydrometer? A hydrometer (hīdrŏm´eter) is a device used to directly determine the specific gravity, or density, of a liquid. This is often used in winemaking, maintaining aquariums, etc. A hygrometer (hīgrŏm´eter) is an instrument used to measure the moisture content of a gas, as in determining the relative humidity of air.

If you have a meter in your case measuring humidity, it is a hygrometer. All this meter does is display the humidity within your case for you. It does not control and cannot change the humidity in your case.


If you live in a very dry or arid environment, or if you live in an area that has dry seasons (such as very dry winters), or if your inside environment is consistently dry, you will probably want to add a humidifier to your case.

Humidifiers for instrument cases come in several designs, such as a small cylinder or tube which contains a material to hold moisture, usually a synthetic fiber or a sponge-like substance. Some humidifiers may actually attach to or fit in the instrument, such as a humidifier that fits in the soundhole of a guitar, or in the f-hole of a violin. All types work the same way. When needed, you recharge the unit by adding enough tap water to moisten the fabric or sponge. If it is dripping wet or water puddles, you've added too much water.

The humidifier works through evaporation: as the air inside your case becomes dryer, the moisture you added to the humidifier evaporates, because the dry air is trying to reach a moisture balance in the closed case. Eventually the humidifier will be dry again, and you repeat the process by recharging it with tap water.


If you live in consistently moist environments, such as near water, near a wet forest or where the rainfall creates damp conditions, you may want to consider some way to dehumidify the inside of your case. You'll usually know if you have a moisture problem if you smell a musty odor within your case.

Dehumidifying the inside of the case is accomplished by adding a desiccant, such as silica-gel or dry clay granules. These materials usually come in small packets, available in various sizes depending on the cubic area needing dehumidification. Desiccant packs should be kept in a compartment inside your case. Do not store desiccant packs inside the instrument itself!

The desiccant packs will need to be replaced on a regular basis as they become ineffective after they have absorbed all the moisture they can. Generally, replacing these every 3–6 months should do the trick, but your hygrometer will show you when they are no longer working. Desiccant cannot be re-used; follow any instructions listed on the packets when disposing of them. Never open these packets, as they may contain toxic substances.

The dehumidifier works through absorption: as the air inside your case becomes damp, the desiccant absorbs the excess moisture in the closed case.

Condensation inside your case

Condensation (visible moisture droplets) can occur inside your case if you open your case soon after sudden changes from cold to hot. For example, if you have been carrying your instrument outside in frigid conditions for an extended time and then enter a warm building and open your case immediately, you will almost always experience condensation on your instrument. This is a natural event which cannot be stopped — but you can slow the process down and even eliminate any possible damaging effects to your instrument, by being patient and using common sense.

Condensation happens when warm, moist air meets the cold, dry surface of your instrument. The best way to avoid condensation is to not open your case immediately after entering a warm building (using this example). Instead, when extreme conditions exist, always allow your instrument to acclimate to the new environment inside its case before opening it. Usually 30 minutes or so will do, depending on how extreme the difference is between outside and inside. You minimize condensation very simply because you're not exposing your cold instrument to warm air (remember, the air inside your case is cold, too!). Any condensation that occurs will happen to the outside of your case, rather than your instrument.

Condensation does not indicate a humidity issue that you need to control. And, do not expect desiccant to absorb the amount of water that may condense in one event. If moisture has condensed on your instrument simply remove your instrument from its case and let it acclimate to the new environment. The condensation will dissappear once the instrument is “warmed up.” Never store an instrument in a closed case with fresh condensed moisture. Always wipe your instrument down after moisture has condensed on it, to avoid any possible damaging effects to its finish or functioning parts.

Do you even need a Humidity Control System?

The answer is: maybe, and in all likelihood, probably not. Only if you live in or travel to areas which have these extreme environments as mentioned. The key word here is extreme. If you are in an area that has a consistently moderate environment, in all likelihood you will not need any type of system at all. Indeed, in these temperate environments, you may even consider leaving your instrument out if its case, or with the case open, for example.

At a minimum you may consider adding just a digital or analog hygrometer. This will allow you to monitor the conditions so you can know if you even have a problem.

If you add a humidification system and do not use it correctly, you can actually cause more damage to your instrument than you will prevent. For example, if you use a humidifier in damp environments, and use a desiccant in dry conditions, you're setting yourself up for disaster. Having a humidification system is not a magic wand: you need to know how and why you are using it for it to be effective.

If you have a humidification system already, by all means go ahead and use it. If you added some level of monitoring or control to your case, follow the simple instructions above, and you should have no problems maintaining a consistent and safe humidity within your case.

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