It's no exaggeration to say that humidity - or a lack of it - is the number one reason that acoustic guitars become damaged. Every acoustic guitar needs the right amount of humidity to play and sound it's best, and this is only more important for higher-end, lightly-constructed guitars. When left unchecked, guitars can become cracked, warped, swollen, sunken or unplayable, and manufacturer warranties don't cover damage from over or under-humidification. The good news is that all of these horror scenarios are easily preventable, with a minimum of effort!


The Basics

Guitars perform at their best between 45 - 55% relative humidity (RH). Builders are careful to keep their workshops and wood storage areas in this range, and stores like ours make a point of keeping our showrooms and case storage rooms at this level.

Acoustic guitars, especially the more expensive ones, are likely to be affected by humidity and temperature because they’re made from ultra-thin sheets of wood and held together primarily by glue, and these organic materials react to fluctuations in their environment. Just as your wooden door becomes tight in its frame when it's wet outside, the wood in your guitar will swell when it's over humidified.

It's important to note that the wood your new guitar is constructed of is constantly changing and shifting. Wood can take several years to settle in its final form and will make the most movement due to humidity changes within the first three years of being a guitar. We recommend bringing your guitar in for a service after the first month of playing to adjust to these shifts.


Over Humidified (Wet) Guitars

Over 60% RH, a guitar will begin to take in moisture from the air around it. If you're playing it regularly, you'll notice that it just doesn't sound as good. This is the sheer weight of water weighing down the thin timbers and preventing them from resonating as they should. You might notice that the action has raised, making it harder to play. This is a warning that your guitar is starting to become affected by over-humidification. A great tip that a repair person once told me is to look for condensation on your windows - this is a sign to check on your guitar!

If left untreated for a couple of weeks or more, you may see more serious signs - the top and back will become swollen (or 'bellied'), which could lead to the bridge detaching from the top, braces loosening from the interior, or even mould and mildew on the guitar! If this happens, remove the strings and take it to your nearest repair shop.

Note: all guitars will have some slight bellying behind the bridge - this is nothing to worry about as long as your guitar is playing as it should!


Under Humidified (Dry) Guitars

Below 40% RH, a guitar will become dehydrated as moisture evaporates into the air around it. A drier guitar is harder to spot as it will still sound good, but you may notice issues with playability - sharp fret ends and buzzing above the 6th fret are both common signs of a dry guitar. Left untreated, the guitar can develop cracks and splits as the wood shrinks, and braces and binding can become detached as the soundboard moves.

This is a common issue as seasons change - heading into winter, many guitars develop sharp frets and notes choking out. These issues are usually rectified during a routine setup and service, something we recommend at the start of every season.


Caring For Your Instrument

The good news is that usually all of these issues can be addressed by a good repair person - even cracks and detached braces can be fixed. That said, it's much easier and cheaper (and much less stressful!) to keep your guitar at the correct humidity level. Here's some tips on keeping your guitar at the RH it was designed for:


1. Where possible keep the guitar in the case. It's tempting to want to display your beautiful new instrument at all times, but air humidity, dehumidifiers, air conditioners, cooking steam etc can all have very adverse effects on your guitar. The case is a micro-climate, meaning that it is less affected by outside factors and protects the guitar from sudden fluctuations in RH and temperature.

You may have temperature and humidity controls within your home already - a good dehumidifier and humidifier will go a long way to keeping your home guitar-safe, but it's a good habit to check your guitar regularly for signs of over or under-humidification.


2. Check your humidity levels. A simple wall-mounted Hygrometer will let you know if humidity is at an unsuitable level. If you notice that it's starting to get outside of the magic 45 - 55% level, pop the guitar back in its case.

D'Addario have also created the Humiditrak system to make checking your case humidity simple - it includes a small Bluetooth-enabled humidity sensor that you leave in your guitar case, which connects to your smartphone and delivers updates and stats, as well as warnings for unsuitable RH. 

3. Get the right humidity control for your case. Australia is a massive continent with extremely varied climates. If you're in a drier area, you may need to add humidity to your guitar with a soundhole humidifier such as the ones sold by D'Addario, Maton or RDM. These simply distribute moisture back into the guitar via a damp sponge.

If you're in a wetter area (such as Queensland), the Boveda High Humidity kit is your best bet - these packets contain a gel that pulls moisture from the air around your cased guitar to keep it at an optimum level.

For most temperate climates (Victoria, NSW, South Australia and Tasmania will usually fall into this category), a two-way humidification system is by far the best option. Boveda's Large Instrument Humidity Kit is the benchmark - it automatically pulls moisture from the air if it goes over 55% RH, and releases it back out at 45% or under. It's a simple, no-fuss method that you can leave in your case and forget about.

Boveda also produce Case Seasoning packets - an often-forgotten aspect of humidity care is that cases usually contain wood, foam and glue, which are also prone to low or high RH - a dry case will pull moisture directly from your guitar, drying it out!


Don't Worry!

While these points are important to remember, we do not expect guitar owners to become meteorologists, or to walk on eggshells concerning the safety of their guitars. But by becoming familiar both with the principles of humidity and with how a normal guitar looks and feels, an owner can prevent almost all damage to a guitar and maintain the guitar’s great playability and tone. Basic precautions include: keeping the guitar in its case when not in use; keeping it out of direct sunlight and extremes of heat, cold and high or low humidity; and regularly checking for any significant changes.


Check out our range of Humidity Care products here


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