Wednesday, September 11, 2013

About Tone Woods

Hope everyone had a great week.
This week I would like to talk about tone woods. What makes them different, and what you can expect in how these woods perform
You might think, like a lot of folks, that a guitar, acoustic or otherwise, is just simply made of wood, and when you put strings and electronics on it, it makes music. Well... it's something like that, but just a bit more involved.
There are a multitude of different tone woods that are used in the manufacturing of acoustics, solid bodies, arch-tops and basses.
Let's start with acoustic guitars.
The most widely used tone wood used in building acoustic instruments is mahogany. Why? Well, it's affordable. It is reliable, (doesn't twist and is a relatively tough wood) it is an attractive wood, and it is easily finished. It also lasts for years, and requires little to no maintenance. But, the biggest reason for using mahogany is that is resonates so well.
Martin Guitars tend to use a lot more of this wood, comparatively to other manufacturers such as Gibson, Larivee, Breedlove and others.
Martin uses Mahogany on the backs and sides of their guitars, as well as the neck and their head stocks.
Martin guitars have a distinctive sound unlike any other guitar. Though other Luthiers and guitar manufacturers have been trying for many years to find out how they achieve the sound they do, even with the right equations and engineering to duplicate the Martin 'sound', they have always come up short. They are truly a remarkable instrument.
Though Martin, like so many other builders, do not like to share their secrets, other builders, even in coming close to duplicating the Martin sound, have in their own right discovered their own unique sound.
The sound of the instrument is not 100% dependant on just the tone woods alone. With Martin, and so many others, it is the right combination of a lot of things.
Let's move on to other tone woods and why they are used, and where they are used on the guitar.
Sticking with acoustic guitars for this portion of this blog, Rosewood is probably the next best choice for guitar builders. Rosewood comes in many varieties. Macassar, Indian, African and the most popular, Brazilian. Rosewood is a very fragrant, oily, and porous wood. Still, when it is seasoned properly, rosewood can be as dense a ebony and duplicate a lot of similar characteristics in tone, but at half the price. Again, this is one of the reasons rosewood is a popular choice for use on acoustic, and some electric instruments.
Where is it used? Rosewood is usually used as fretboard material, headstock laminate and most importantly on the back and sides of the instrument. As a soundbox choice, (the back and sides of the acoustic guitar) rosewood is less aggressive and more resonant than mahogany, it's cousin, but if used on dreadnaughts and jumbo guitars, rosewood provides a very rich and distinctive tone. Rosewood has been used for years by many manufacturers as an alternative to mahogany and other tone woods. Rosewood is also used in the manufacture of the bridge plate on the guitar, as well as the sub plate, that is the plate affixed to the guitar's bracing and is attached to the underside of the soundboard, or 'top' of the instrument. Rosewood is also used as the inner purfling on a lot of higher end instruments. Why? Simply because it vibrates and resonates better.
The only problem with rosewood is that it is a somewhat 'oily' wood, which makes it difficult to adhere to the neck material, as well as the soundboard on acoustics. Great caution has to be taken to make sure the wood is properly conditioned and seasoned, or 'aged' as well as the use of correct adhesives for the process.
As guitars mature, one will often see where binding attached to rosewood has started to crack and craze and eventually pull away from the instrument. Gretsch and Gibson, to name a few, are re-knowned for these issues. Gibson also had problems with their rosewood bridge plates lifting on their guitars, and eventually moved on to a different wood for this purpose.
Ebony is next on the agenda.
Ebony is a very dark, black wood. It is very dense and somewhat fragile with age, if not conditioned properly.
Where is it used on the instrument? Usually ebony is used as fretboard material, but can also be used as a bridge plate, or a laminate with other woods for dressing a headstock.
Ebony has an advantage over rosewood in that it is extremely dense, less prone to wear and usually works well in adherence to other woods like mahogany.
A huge advantage in using ebony as a fretboard material, is that ebony does not wear out like some rosewoods do. So there is never the concern to having 'divots' in your fret beds.
These divots, or wearing out of the fret beds (in between the frets) has always been a great concern to manufacturers, because when this happens, there is usually little one can do to repair this, but replace the fretboard, or in some cases, even the entire neck on the instrument.
Now that is all the good stuff about ebony. Surely there has to be some disadvantages right?
Well, to answer this...yes there is.
The biggest problem with ebony and its choice for either a fretboard, or a bridge plate, or anything else on the guitar, is simply that it is a very fragile wood. Ebony never stops expanding and contracting as it takes on and expels moisture and humidity. This is caused by the raising and lowering of the humidity in the ambient air in the guitar's environment, and also from the very moisture in your hands and fingers. Due to the constant changing of this wood's conditioning, it is prone to crack, and it can also cause problems with adhesion on either the neck, or contact with the soundboard.
The largest problem with ebony is fret removal. When used as a fretboard, ebony can become very stiff and fragile, and when frets need to be removed and replaced, the fret slots can gaul or shatter. Caution and care have to be used when removing frets on an ebony fretboard, and this is usually done with the use of heat, by means of an iron, and very slow and careful removal of these frets. In many cases, when new frets are installed, they usually have to be glued into the fret slots, and then clamped individually so as proper adhesion can be assured.
Another disadvantage of ebony, is that it is not always readily available, and it's cost far out weighs rosewood.
Though there are definitely advantages and dis-advantages to both, rosewood seems to be the favourite choice by most makers for fret boards and bridge plates.
Next week we'll talk a bit about soundboards, and what woods they are made up of, and we will touch on some electric guitars as well, and what woods they are made up of.
Until then.....take care, and keep playing.

Brett McNaueal

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