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Case humidifier

A device placed inside a guitar case that releases moisture slowly to keep the instrument at a safe humidity level.

Solid wood instruments settle into shape while the wood holds a particular moisture content, and when the surrounding air gets too dry the top shrinks, the fretboard contracts over its frets and the action changes. A case humidifier is the simplest control: a sealed case keeps whatever moisture the device releases around the instrument instead of letting it disperse into the room. It must be refilled regularly and kept from direct contact with the finish, since a saturated object touching bare wood can stain it.

Example: A guitar stored in its case through winter with a small damp sponge in a perforated holder is using a case humidifier.

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