At Alvarez we do all we can to make guitars that are responsive and will last a lifetime. We’re going to take a deep dive into how humidity affects your acoustic guitar so that you can protect and care for your instrument for years to come.
First, here is some advice on how best to look after your guitar:
The best temperature range for guitars is 66-77° F (19-25° C). The ideal Relative Humidity is 40-50%.
If conditions change beyond this, please consider using a humidification system in your case, and it’s always best to have a humidifier for the room where you store your guitars, especially if they’re out of the case. Regarding humidification systems for your case, we would recommend the D’Addario® Humidipack, two-way system.
Trees love water; they are designed to allow fluids to circulate around its wood for it to thrive. At a cellular level, the structure of wood has cells which are specifically designed to distribute water. Other cell types promote growth, strength, and nutrients. When we cut a tree and use it to make a guitar, the cell structure that allows water to be absorbed and released is still functional.
Therefore, even though the wood is no longer a tree, it is still active, and in a way, still alive and thus a very porous, elastic material.
Understanding the effects of low or high humidity to a guitar are simple.
Both reactions are due to the cells either absorbing or releasing moisture due to the Relative Humidity of the air the guitar is subject to.
Relative Humidity is the amount of potential water vapor (water molecules) present in the air at a given temperature, expressed as a percentage.
The temperature of air is important. The warmer the air, the more moisture it can hold; conversely, cold air holds less water vapor. Absolute Humidity is the total mass of water vapor in a specific mass of air; it does not take temperature into consideration.
In other words, Absolute Humidity is the amount of water vapour in the air; Relative Humidity is the potential amount of water vapor in the air, relative to how warm or cold it is.
So, for example, if you were outside and took a sample of air and measured the water vapor in it, that would give you the Absolute Humidity. Then if you kept that exact sample of air and took it into your home, where temperature was higher because you had the heating on, the air temperature of the sample would change, meaning the humidity would too. This would be measured as Relative Humidity.
Cold air holds less water vapor than warm air, so low humidity is most common during the winter months, and therefore the air is generally dryer.
There is also the effect of heating in your home, which can have a huge impact on Relative Humidity as we heat the cold air from outside. Heating the air in our homes during winter, when the humidity is low in the first place, quickly expands the air as we heat it, but because there is no other source of moisture, the water vapor that is present is immediately diluted by warmer air with no constant source of moisture, and Relative Humidity plummets.
Dry air can very quickly affect your guitar top and fingerboard.
This is because the cells of the wood which hold moisture start drying out, and once these cells are dry, they contract and the wood will shrink. This will cause fret ends to become exposed as the fingerguard contracts. Worse still, the neck angle will change as the cells of the soundboard contract and the arch in your guitar top flattens out, lowering the bridge and taking the strings closer to the frets. So initial signs can be sharp fret ends and fret buzzing.
If your guitar continues to be exposed to low humidity, it can happen quickly—the top or even the back will contract further and will likely split. This will require a major repair, and sometimes, depending on severity of the contraction, or the size of the split or crack, it is often not cost effective to repair the guitar.
So, keep an eye on your hygrometer, get to understand what conditions can do to your guitar and take precautions!
Warm air can hold more water vapor than cold because it expands due to the heat. In hotter areas, water continually evaporates, and therefore more water vapor rises into the air and raises humidity.
So, high humidity is more likely to occur in hotter areas or the summer months, but only if there is a source of moisture. For example, a summer day in Death Valley, Arizona will likely have a relative humidity below 10%, even though it is hot, simply because there is little water or moisture to evaporate and create water vapor. Somewhere like St. Louis, where Alvarez is based, is hot and humid in the summer. Even though it is not near the ocean, it is affected by warm, moist air that originates in the Gulf of Mexico in the summer, and cold air from Canada in the winter.
So, places of high humidity can be humid for a several reasons, but one thing for us to be aware of as guitar owners is that no matter why it is humid, it can still severely affect your guitar.
The cells of the wood in your instrument can quickly take on water vapor and this will expand the wood. It is particularly impactful on the top because the top can swell, which will change the neck angle as the bridge will rise and create a high action. This makes your guitar more difficult to play. If your guitar is subject to very high humidity levels for long periods of time, further damage can be caused from swelling. Glue joints can fail, or finish can react and even lift. The tone of a wet guitar is also affected; it will sound dull and lifeless compared to the way it was designed to sound.
So in humid places or humid times of the year, watch out for the top overtly swelling, or a change in how your guitar reacts if it becomes dull-sounding.
Again, keep an eye on your hygrometer, get to understand what conditions can do to your guitar and take precautions.
Like all well-made acoustics, Alvarez guitars should always be kept in an environment between 40 and 50% humidity. It’s fine to keep your guitar out on display in the right environment – whether it’s hanging or on a stand – but the best way to store a guitar is in its case, away from direct sunlight. If you are travelling with your guitar or experiencing heightened dry, cold or damp conditions, then you should always use some sort of humidification. We recommend the D’Addario 2-way Humidification Pack System, as it can both release moisture in dry conditions and absorb it in high humidity.
String shelf life has a lot to do with player’s preference. There are artists that change their strings for every show, and there are professionals that like the gritty twang of an older set. Generally a new set of strings will take a few days to break in, and with regular playing, will sound bright and fresh for weeks, maybe even months. With all that in mind, the most tested, tried and true way to tell if it’s time to change your strings: if one breaks!
Guitars should be cleaned regularly to prevent any permanent damage to the finish and fingerboard. Our skin and fingertips carry a lot of natural oils and acids that can build up and cause stains or more rapid oxidation on the frets. There are many products on the market that claim to restore a guitar’s finish, but chemicals and solvents can sometimes do more damage than good. The best way to clean your guitar is with a damp soft towel or a microfiber cleaning cloth, leaving no moisture behind. A q-tip is always good for the hard to reach areas or for the fine cleaning that frets need. We also recommend lubricating your fingerboard and bridge every few months. We use D’Addario Lemon Oil.
Your Alvarez comes with an excellent Limited Lifetime Warranty that will cover any rare defects that may contribute to damage. Beyond the scope of the warranty, if you or someone – or mother nature – damages your guitar, we have a guitar shop that is second to none, and can restore your Alvarez for very competitive rates.
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