In the first part of our series about humidity and acoustic guitars, we took the time to define what humidity is and how it’s measured (RE; relative humidity percentage). We went into many things that can happen to your guitar if it tends to live in a dry environment (RE: not enough humidity) or is kept in a more moist atmosphere (too much).

Thankfully, several different guitar accessories will help to keep the relative humidity right where it needs to be. We’ll take a look at those and point out the pros and cons of each. After that, we’ll take a quick detour into how humidity can affect other guitar types.

Let’s get the ball rolling!

Guitar humidifiers

The best way to combat the effects of improper relative humidity on your guitar is to keep it in a controlled environment. That being said, it’s probably safe to say that most guitar players do not have a separate room where they store their instruments, particularly one that has the relative humidity set to that 45%-55% ‘sweet spot.’

So what’s a guitar player to do?

That answer is simple – store your guitar in a quality case and use a ‘guitar humidifier.’ These accessories keep moisture in the air, and using them while your guitar is contained in a case is probably the next best thing to having a fancy room set up in your home.

There are several different types of guitar humidifiers, and for the most part, they are reasonably inexpensive. The process and technologies used can vary quite a bit, so it’s a good idea to understand how the different kinds work in practice.

Water (sponge) based guitar humidifiers.

These are the simplest type of guitar humidifier that you may come across. They are nothing more than a plastic shell that has vent holes in it. Typically there is a cap on the body of the cover that can be removed. Inside there is nothing more than a simple sponge.

Guitar humidifier

To use this type, the sponge has to be damp. Notice we said damp – not wet. It’s easy to think that having the sponge be as wet as it can be will help with the humidity, but you actually may be taking a chance of damaging your acoustic. The sponge should never be so wet that it can drip out of the shell. Why? Well…water and wood tend to not play well together!

“Once in a while, the thumb that fits over the neck of the guitar kinda bothers me a little bit, but not that much yet. I figure in time I won’t do much because of my age.” B. B. King

Guitar humidifiers of this type are designed to fit between the strings and protrude into the guitar’s body. The body is where the thinnest wood pieces on an acoustic are, and therefore it’s the area that can be most affected by improper humidity.

Acoustic guitar humidifier

While sponge-type humidifiers are cheap and easy to use, there are some drawbacks. First off, there really is no guitar case (or even a high-quality gig bag) that is genuinely air-tight. That means, over time, the water vapor inside the case will eventually evaporate out, and the sponge will become dried out. It’s not uncommon to re-wet it a few times a week.

Plus – and this is another real-life example here – there can be problems with mold. Care must be taken to make sure the sponge is always in good shape. Mold can start to grow, and when it does, it’s best to throw that sponge away and get a new one (you can find multi-packs of sponge refills reasonably comfortable).

One other challenge to using sponge-based guitar humidifiers is that you really have no way of knowing the relative humidity inside the case. To solve this problem, some accessory manufacturers offer kits that include a guitar humidifier and a device called a ‘digital hygrometer.’ It’s essentially a sensor that measures relative humidity and has a display so you can quickly tell if your case is too dry or too wet.

Guitar hygrometer

Humidifier setups with digital hygrometers may cost a bit more and take more effort to use correctly. Still, it’s a more accurate method of ensuring your acoustic guitar’s environment is correct for proper storage.

‘Automatic’ fluid packs

Another option that dramatically reduces the guesswork in keeping the relative humidity needs to be automated fluid-filled packs. These packs are actually pretty innovative. They are constructed from a particular type of paper enclosure, a proprietary gel-like material sealed inside it.

The combination of the paper and the gel allows an exchange of water vapor within your guitar case, and they self regulate the relative humidity. More moisture is released when the humidity is too low, and any excess is absorbed when it is too high. The design keeps the humidity percentage right where it needs to be, without messy sponges or the need for checking a digital hygrometer.

Sounds too good to be true, right? Well, there’s no denying that this type of system is most likely the easiest and most trouble-free way to keep things on point. But there are a few downsides. First off, the packs will wear out and eventually lose all effectiveness over time. It can take a few weeks or months, depending on the overall environment where the guitar is being stored.

Since the packs wear out, that means they have to be replaced. And that means you have to continually purchase new ones. The overall cost to use the fluid pack option can add up to several times over what a cheap sponge type model will cost – even if you factor in a digital hygrometer price.

Guitar humidifier

As with most things, though, convenience comes at a price. If you want to just ‘set it and forget it,’ and you don’t mind paying a few bucks every now and then, using fluid packs may be your best choice.

Effects of humidity on different types of guitars

We have focused our discussion regarding humidity and guitars, mostly on acoustic guitars. That’s because they are the most fragile type of guitar that you will come across. Not only is the construction composed of relatively thin pieces of wood, but all of the joints are also secured with adhesives.

Electric guitars

Electric guitars are typically much more robust than an acoustic guitar. Solid-body models are remarkably rugged, as they should be – they are solid slabs of thick wood that are frequently screwed together (that is, the neck to body joint). But can improper humidity affect an electric as well?

It sure can – just not in the same extreme ways as an acoustic can be (considering the entire instrument can become damaged beyond repair). You can tell when things get too dry with an electric when you actually feel the frets’ edges as you play up and down the neck. This means the neck itself has shrunk.

Extreme cases of being too dry or too wet can lead to poor playability and possible neck twisting and/or warping. So yes – electrics are susceptible to the effects of poor humidity control as well.

Acoustic guitars with laminated wood

Another type of guitar to consider is an acoustic that uses laminated wood in its construction. Laminated wood is basically several thin pieces of wood that are glued together, similar to plywood. Many lower-cost guitars are constructed entirely with this kind of material, mostly because lower and laminated wood can be stronger than solid pieces.

For the most part, mid-to-high level acoustic guitars are made with a solid top (typically some type of spruce) with laminated backs and sides (here is where the strength is a benefit). The solid tops tend to sound better and allow for more efficient vibration transfer, but they can also be affected much more by improper humidity levels than laminated tops.

Guitar laminated wood

While laminated tops are more robust, they aren’t bulletproof. They may not get damaged as easily by humidity as a solid top, but it may not hurt to use some sort of guitar humidifier just to be safe.


It can’t be overemphasized how much improper levels of relative humidity can affect your guitar. The best strategy to combat any ill effects is to be proactive. Use some sort of guitar humidifier to keep the relative humidity percentage in the acceptable range. And while it’s true that some types of guitars (other than solid top acoustics) may withstand improper humidity better than others, it’s always better to be safe than sorry.

Humidity is a natural condition that can’t be avoided entirely. Proper attention to its effects should be a part of any guitar player’s overall maintenance plan. If you stay mindful. You can be assured of beautiful playing experience for many years to come.

Chat with other guitar players about your guitar’s humidity environment in our guitar chat forum.