The Guitar Humidity Website!

Welcome to The Guitar Humidity Website!

Table of Contents

1. Introduction
2. What Is Relative Humidity?
3. How Humidity Affects Acoustic Instruments
4. What to Do About It?
5. Regional Differences and Weirdly Specific Advice if You Live in the New York Metro Area
6. TLDR/Conclusion

Introduction

So, you've found yourself on my humidity website. Do you have a guitar that is dry, cracking and buzzy? Maybe you have a guitar that's overhumidified, crazy difficult to play, and doesn't stay in tune. Perhaps you were sent here by a family member, loved one, or extremely concerned guitar technician. Whatever the reason, I aim to educate you in the ways of humidity. This is mostly aimed at acoustic guitar owners, but the information is applicable to most wooden musical instruments. By the end of this article, you should be a humidity expert too!

What is Relative Humidity?

Before we can answer "what is relative humidity?" we must first answer "what is humidity, you know, without the relative part?".

Humidity is the invisible water vapor that is dissolved in the air. Humidity is NOT a mist, or any form of visible or liquid water. Please do not use any liquid water directly on your guitar. It will either do absolutely nothing or permanently damage your instrument.

Now that we know what humidity is, what is relative humidity? Relative humidity is a way of expressing how much water vapor is in the air as a percentage. 0% relative humidity means that the air is currently holding no water vapor, and 100% relative humidity means that the air is holding so much water that it physically cannot take any more.

Here are some examples of what different relative humidities are like:

• 0% : the air would feel very dry. If left in this environment for 24 hours your skin would dry out, and your lips would get chapped.
• 50% : this is a comfortable humidity for most individuals. The air would feel neither dry, nor humid.
• 80% ; this is a very humid environment. You would likely be able to feel how moist and muggy the air is on your skin, and perhaps even smell a moldy/muggy smell.
• 100% : the air has been completely saturated with water, and can't hold on to any more. The excess water comes out in the form of liquid or solid water. We experience this as fog, rain, snow or hail it. Is known as precipitation.

How Humidity Affects Acoustic Instruments

All this humidity garbage is nice and all, but how does this actually affect guitars? Well, most guitars are made out of wood. Wood, as it turns out, is extremely sensitive to humidity. If left in a humid environment, a piece of wood will get larger, and if left in a dry environment it will shrink. Generally, you want to keep your guitars at 40-60% relative humidity.

Let's look at what happens to a guitar at varying relative humidities. For this example, we will assume the guitar has been left in each environement for at least 1 week

• 15% (dry) : the guitar is going to have very low action (the height of the strings off the fretboard). There is a very good chance the gutiar is unplayable, if it is playable then there will be significant fret buzz. There could also be structural issues such as cracks in the body, lifting bridge and/or internal bracing that is disconnecting/cracking. The edges of the frets might also poke out of the side of the neck now, as the neck has shrunken.
• 50% (perfect) : the guitar is just about right. No issues, normal action, etc. This is where a guitar "wants" to be. Acoustic gutiar factories, show rooms, and repair shops all aim to keep their environments around this humidity.
• 80% (overhumidified) : the guitar is going to have very high action. You also might experience structural issues such as bracing popping off or bridge lift. You also may experience mold growth on the inside of the guitar or case. There may be condensation forming on metal components of the instrument, such as the tuning machines.

What to Do About It?

First thing that I recommend you do is play your instrument and inspect for signs of over/under humidification. Is there fret buzz on the high frets? Are there any cracks in the body? Are the fret edges poking out?

Next, go to the hardware store and buy a hygrometer and a long ruler/yard stick. A hygrometer is a device that measures relative humidity. Place this wherever you store the guitar. If you keep your guitar in the case when you're not playing, keep the hygrometer in the case. We will come back to this later

As far as the yard stick is concerned, you wanna place this over the lower bought of the guitar (reference images below). We are going to use this to determine the curvature of the top. If the top looks concave (sunken in), then the guitar is dry. If the top is convex (bellied out) then the guitar is either perfectly humidified or possibly over humidified.