Guitar repair: Owners of solid wood acoustic instruments, don’t say I never warned you!

Look carefully at the photograph above and check out the humidity levels. If you own a solid-wood instrument, are situated in North India, and the humidity is below 45%, this post concerns you and this post should concern you. In this scenario if you’ve left your solid-wood instrument tuned to pitch and standing in a corner of your house, you should be very worried!

A refresher course

What is a solid-wood instrument? One that has the top made out of a single wood, and the back and sides also of a single wood, eg, spruce/cedar for the top and mahogany/rosewood/walnut for the back and sides. Thus, they are also referred to as single-wood instruments. ‘All-mahogany’ and ‘All-koa’ wood instruments (having top, back and sides of mahogany or koa wood), also fall in the solid-wood-instrument category. 

How do you know if it is a solid-wood instrument? Carefully note the ‘design’ of the grain of the wood on the top or back, or sides. Now try and spot the exactly the same pattern at exactly the same place on the inside. If you find it, hurray!

What is the ‘other’ kind of instruments? Ones that have a thin veneer of spruce or mahogany but under that, the bulk of the wood is some ordinary wood. Or, an instrument that is made up of several thin layers of different woods. Thus, the ‘other’ instruments are also called laminate-wood instruments.

What is the difference between the two? Price and sound quality! A laminate-wood instrument will always be cheaper than a solid-wood instrument. Understand the issue like this: a leather jacket which has only two pieces for the back and the front, and single pieces for the sleeves, will always cost more than a leather jacket made up of leather patches.

A solid-wood instrument produces a much ‘purer’ sound than a laminate-wood instrument. Revisit the school physics class where the teacher was talking about refraction of light. Remember how that ray of light passed straight through a homogeneous material, retaining its intensity, and how the same ray of light came out crooked passing through a heterogeneous material, with lower intensity?  Much of the same happens to sound waves as they traverse through single-wood (homogeneous) instruments and laminate-wood (heterogeneous) instruments.

A solid-wood instrument, despite its advantages and price, is a delicate instrument, akin to a pure-bred pet that demands a lot of attention, care and maintenance. The laminate-wood instrument is like a mix-breed pet, not given easily to diseases and ailments that normally afflict pedigreed pets.

The solid-wood instrument, due to the nature of the wood used, is also given to dramatic effects of nature: too much humidity, too little humidity, high temperature fluctuations, etc. Laminate-wood instruments, due to the nature of the wood used, are not given to these effects.

So, if the solid-wood guitar is so much hassle, why buy it? For the sound of it, baby, the sound! Play a solid-wood instrument and you will never be able to play a laminate-wood instrument again.

Course ends!

Right! So, the humidity in the atmosphere is less than optimum for your (solid-wood) guitar. And you’re certainly in trouble if you have left your guitar tuned to pitch and not played for even 3 – 4 weeks.

Here’s why. Wood is an organic material and reacts to changes in weather conditions. Reduced humidity in the atmosphere sucks the moisture that is present in the wood. Add to that the force being applied by the strings. In a laminated guitar, because different woods have been used, those woods lose moisture at different rates, making the instrument much sturdier. A solid-wood instrument succumbs all too easily.

It often starts off with a fret buzz. The loss of moisture from the neck pushes into a back bow, pulling the strings closer to the fretwires.

Don’t be surprised if you see the centre seam separating on either the back, or the top, or, both! The wood loses moisture and the glue eventually gives up holding the two halves of the back or the top, or both together: much like this one

Beware! Dry weather can do this to your guitar too!

In some (solid wood) guitars, loss of moisture from the wood also causes the area of the top behind the bridge to sink – the opposite effect of the belly bulge. While the belly bulge may partly be caused due to over-humidification, the belly sinking is a sure sign of a dried up instrument.

Pic courtesy

Equally dramatic is the effect on bridges. Look at the bridge pin holes – six perfect breaks in the grain of the wood – a huge incentive for the bridge to crack, stuffed as it is with strings and bridge pins. Add to it the loss of moisture and you have the perfect recipe for a bridge-split. Just like this one

Split bridges – here’s an Ibanez!

Often, a thin but obvious crack, running under the fretwires, through some length of the fretboard is a sure sign that the guitar is dry and dehydrated. Correcting this is some job indeed. Fretwires through the length of the crack need to be pulled out, the crack needs to be filled and then the area sanded level. Then the frets have to be reinstalled and (many times need to be) levelled, crowned and polished.

Pic courtesy

When the dehydration is to a lesser degree, one sees a phenomenon called fretwire sprout. The wood shrinks having lost (some of) its moisture content. However, the fretwires are metallic and remain their original length, giving the impression of having ‘outgrown’ the fretboard.

Pic courtesy

The Remedy

KEEP TRACK OF THE HUMIDITY! As soon as humidity levels fall below 45%, know that your guitar is thirsty. Give it that life-saving drink of water.

While there are umpteen contraptions available in the market to humidify your guitar, remember, the idea is to put the water back into the guitar that it lost. A small plastic vessel containing water stood in the guitar will also do the trick, as long as it does not tip over.

Keep the water in the guitar for a few days and repeat the process the following week and the one after that till the outside humidity levels return to being above 55%. Of course, if you put the water vessel and forget about it for a few weeks, that also works. However, for people who must play the instrument every few days, the first method works well.

Whichever method you choose to follow, by doing it, you ensure that your guitar has all the moisture it needs. By following it religiously, you will ensure that you don’t have to encounter all the problems described above, when the humidity dives. If the damage is small, rest assured that enough humidity will return it close to normal.

For the rest of the procedure, I remain at your service!!!





Amit Newton

An experienced guitar tech with over 10 years of experience working on acoustic Gibsons and Martins in the Gulf region. There is nothing that cannot be repaired; the only consideration is the price at which it comes. And yet, if there is sentiment attached, no price is too high! WhatsApp/Call me: 7080475556 email me:

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