If you are like me and have too many guitars (is that possible?!), you need to be thinking about humidification during the winter months, and possibly year round if you live in a drier desert climate. Keeping a room at proper relative humidity is very easy, regardless of how cold or dry your climate may be. Picking the right machine to do the job is key, and that is determined solely on how much humidification you need based on room size and the climate where you live. It is important to note that some people living in tropical areas may need to check into
dehumidification,
and there are plenty of these units on the market. For the purposes of this article, I am going to focus solely on humidification as it relates to cold winter temperatures and/or dry desert climates, which can dry out and severely damage a guitar.
Proper relative humidity levels for any guitar (acoustic or electric) is between 45% and 50% (also the recommended RH for human comfort. The same goes for temperature... if you are comfortable, your guitars will be comfortable). The warmer air is the more water vapor it can hold. If the temperature outside is 40 deg. F with a relative humidity of 50% and you have the heat on in your music room to bring the indoor temperature up to 70 deg. F, that warmer air is going to have more capacity for water vapor and relative humidity is going to drop. Adding to the drying effect is the heating process itself, especially if you are using an HVAC system for heat. Uptake vents suck all the moist air out of the room and warm, dry air is blown back in through the main vents. The combination of cold air expansion during the heating process
and the dry HVAC air blowing back into the room can cause the relative humidity to plummet. This causes anything in the room to dry out, literally sucking the moisture right out of objects... especially objects made from wood.
So, what type of humidifier should you purchase? Well, that's a tough question to answer exactly. I tend to prefer the
cool mist, atomizing humidifiers because they can be placed right next to furniture or instruments without getting them moist with water vapor. However, one major drawback with these units is that they can be very loud since they use large fans blowing over a water reservoir in order to do their job.
Warm misting units work well and generally are quieter than cool mist units (although most produce "gurgling" and "spitting" sounds). Relative new comers to the game are
ultrasonic units that use a vibrating plate to produce a plume of water vapor that shoots several feet into the air. As with warm misting units, this vapor rapidly evaporates, but there is still some risk with proximity to delicate objects in the room. The ultrasonic units are all but silent, which makes them ideal for a music room.
I have two noisy, cold-air units (one a 2.5 gallon and the other a 1.5 gallon) that do a wonderful job of keeping my roughly 200 sq. ft. guitar room somewhere between the ideal 45% - 50% RH range regardless of outside temperature or how often the heater kicks on. The trade off is noise. I test the RH level in my room with a digital hygrometer I have installed on the opposite side of the room from the humidifiers. I highly recommend buying a good,
digital hygrometer.With both my units on the noise is pretty unbearable, so one usually is shut off while I am playing or working on my guitars or amps. When I shop for a new unit in the future I will consider a more powerful ultrasonic humidifier with a 5 gallon or bigger reservoir that is capable of dumping all 5 gallons within a 24 hour or faster period, which should eliminate my current need for two units (and cut down on the noise). I also recommend a programmable unit that will turn itself on when it falls below the level you've set or off when it goes over that level. The hygrometers on most humidification units are notoriously inaccurate, but when used in conjunction with a good quality, stand-alone digital hygrometer they can be programmed quite effectively.
Regardless of which type of unit you pick, if you're not humidifying your music room during the winter months you should start now! It cuts down on set up issues and can actually prevent serious, expensive damage to acoustic guitars. Tell tale signs your guitar is too dry in the winter are protruding fret ends, crazy high action on electrics or low action on acoustics and, in some extreme cases, cracks will appear on acoustic guitar tops or backs.