Humidity, Guitars, Truth and Prevention

Winter is coming. When it comes to the structural integrity of your favorite acoustic guitar, this could spell trouble. Small issues that affect intonation or action on a guitar may be telltale signs that it may not be properly prepared for a cold, dry season. The changing of the seasons naturally brings changes in humidity, and along with the way a guitar is kept and stored, these changes could dry a guitar out. The effects of a dry guitar can often be reversed, but sometimes if the condition persists too long, moderate to severe damage can occur. Airing on the side of caution today can do wonders for your guitar and prevent major damage and repairs down the road. With a couple of quick points, you can get up to date and informed on the best practices to keep your guitars safe this season.

Relative Humidity and Safe Storage

Relative humidity is the amount of moisture air can hold at a given temperature. Since temperature has a direct effect on the humidity of the air, it will influence the humidity of your guitar. Guitars are most comfortable at around 50% relative humidity. Some may say anywhere from 48% to 52%, but to keep it simple, 45% to 50% is ideal. In the Atlantic northeast, the humidity in your home will very likely not be close to 50% in the middle of the winter, so it's best to take action quickly.

The Dangers of Low Humidity

Your acoustic guitar is not finished on the inside so moisture can come and go as it pleases with no resistance from inside of the body. The top of your acoustic guitar holds about 1 to 1.5 oz of water at proper humidity, so when it dries out, it actually shrinks. When the top shrinks, it can sink to the point where the action can get low enough that that strings can lay across the frets. As it continues to dry out, the carefully fit glue joints can come loose. Since the bottom of your bridge has a radius to match the top of your guitar, the bridge can come partially or completely unglued when the top shrinks and changes shape due to low humidity. The same can happen with internal braces and/or glue joints where the sides meet the top or back. If the glue joints don't come loose, that is when something else has to give. This is where humidity cracks come from. When the guitar is dried out, a glue joint or the wood itself can give out. In many cases, it's both.

Quenching Thirst and the Mass to Moisture Ratio

A few years ago, on a trip to Talyor Guitars in El Cajon, California, we learned some new-to-us information that changed the way we discuss guitar humidification. Taylor painstakingly maintains a 50% humidity throughout the factory with ultrasonic mist machines, much like we do in our shops. However, Taylor was having a problem years ago where customer repaired guitars were developing issues upon return. Properly humidified and carefully repaired, guitars would return to their loving homes only to develop humidity issue soon after. The culprit, as it turned out, was a room at the factory that was not humidified where the service department was storing customer guitar cases while the guitars were separated and being properly humidified in a high humidity room. The danger was in the details: the average guitar holds 200 grams of moisture at proper humidity while the average case holds 500 grams of water. If you put your humidified guitar in the dry case that has more than twice the mass of your guitar, the case will sap the moisture and bring your guitar back to square one. The solution is to humidify the guitar AND its case as a part of the service and repair.

Preventing Humidity Damage

Preventing humidity damage comes down to the three important aspects: knowledge, awareness, and commitment. First, keep the how's and why's of guitar humidity in mind. Be ready to recognize the effects of humidity on your acoustic guitars. Second, take action to get a humidistat and check the moisture level of your home. The numbers on your residential humidifier or dehumidifier are not accurate, they are rough estimations so it's best to have a gauge you trust to calibrate against. Knowing the true climate of your home will give great insight into the systems and practices that will work best for you. Lastly, make sure to stay on track to keep your guitars safe and playing their best throughout the seasons. Commit to the best practices in humidification to protect your investment and guarantee its long life.

Taylor Extech Mini Hygro Thermometer
Taylor Extech Big Digit Hygro Thermometer

Our Winter-time Recommendations

While keeping proper humidity of a room or house might seem like a good solution it is in fact quite a challenging feat. Keeping a guitar humidified in its case is much easier and more manageable. For that, we can suggest a couple of products to help get the job done.

D’Addario Two Way Humidity System

The D'Addario Two-Way Humidity System is a foolproof way to maintain your guitar and case at around 48%, which is perfect. The system is bi-directional and will push out and pull in moisture as needed to regulate until the packs wear out. This works really well in all seasons to maintain your instrument and case. The system consists of three pouches with replaceable gel packs that live inside your case with the guitar. In our experience, packs can last anywhere from two to six months or longer, depending on climatic conditions. For monitoring conditions inside your case, D’Addario makes a Bluetooth Humidity & Temperature sensor that can send your in-case conditions right to your phone.

D'addario Humidipak Humidity Control System
D'addario Humidikit - Humiditrak & Humidipak Bundle
D'addario Humidipak Packette Replacements

Oasis Case Humidifier

This product consists of a permeable fabric bottle with a chemical powder inside, that when filled up, holds 32 grams of water and lets it out into your cased guitar environment slowly. When the bottle shrivels up, it's time to add more water. The next dry season, just replace the chemicals with a replacement packet and you’re good to go. This system also serves as an excellent “reservoir” for your D’Addario Two-Way Humidity System. It can extend pack life and help extend time between feedings if you’re away from your instruments.

Oasis Case Humidifier

PRO TIP: When using any case humidification system, close your case with the humidifiers inside when you are playing your guitar. As my grandfather would say, “Are you trying to humidify the whole neighborhood??!!”