As guitarists, when we buy a new instrument, the spec sheet is a very valuable resource. It tells us all we need to know about the guitar – from the wood it is made of to the pickups, etc.
This gives us a good idea of what the guitar will sound like and how it will play. But one aspect that is often overlooked is the finish used on the guitar.
Either because we don’t regard it as important or we simply don’t understand its importance. The truth is that the finish does play a fairly important role in the overall quality of the instrument.
That is why today I want to discuss why finishes are applied to guitars, why they are important, and some of the most popular types of finishes.
Table of Contents
Why Finishes Are Important
The first thing I would like to go over is why finishes are applied to guitars. There are two main reasons for applying a finish.
The most obvious is perhaps for aesthetics. Different finishes give a guitar a certain look. Certain finishes help to emphasize the grain of the wood and give the guitar a more vintage look while other finishes will make a guitar look more modern.
They can also be split into two types or styles of finish. A gloss finish is more reflective, giving the guitar a shiny look. A matte finish isn’t really reflective and gives a guitar a more “solid” look.
The less obvious but more important reason for applying a finish is for protection. Since a guitar’s neck and body are made of wood, they need protection from the elements.
Wood is a delicate substance and is easily affected by things such as moisture and temperature changes. These can cause the wood to warp, crack, and even rot.
That is why finishes are applied to help prevent the wood from decaying too fast, making it last much longer than it would otherwise. It also helps to seal in the qualities of the tonewoods.
Types of Finishes
Oils And Waxes
The first types of finishes used on guitars were made from beeswax and plant-based oils.
Oils and waxes are fairly popular for acoustic guitars since they don’t affect the instrument’s tone too much. This is useful if you want to retain the natural qualities of the tonewoods of the guitar.
These finishes also don’t change the look of the guitar much. Instead, they simply enhance the grain of the wood, giving it a more vibrant look.
They are also fairly easy to reapply on your own, but the wood does need to be prepped beforehand. Oils and waxes can also be combined to add further protection to a guitar.
Another popular type of finish for acoustic guitars. Shellac is made by female Lac Bugs.
This type of finish also retains the natural qualities of the tonewood, meaning that the tone of the guitar stays unchanged. Unlike oils and waxes, Shellac is much glossier and tougher while remaining lightweight.
The biggest benefit of Shellac is that it is an excellent sealer. This helps to protect guitars, especially more fragile ones from moisture. It is also non-toxic and doesn’t stain or yellow the wood of a guitar.
Shellac can also be applied easily with a brush or spray. It can also be removed very easily with alcohol, making home repairs possible for anyone. The downside is that it needs at least a week to dry and settle.
A very popular finish for electric guitars, nitrocellulose lacquer, or ‘nitro’ for short, is a combination of plant-based cellulose and a nitro solvent. Nitro is frequently used because of its ability to maintain a guitar’s wood resonance and for the warmer quality it adds to the tone.
Nitro is a fairly lightweight finish and doesn’t add any noticeable weight to a guitar. It isn’t the toughest finish, though. The solvent evaporates over time and the cellulose is very susceptible to extreme conditions.
Nitro can be reapplied easily enough to patch up areas that have degraded. It does give a guitar a very nice road-worn look, though, that many guitarists like.
Just be careful when buying a guitar with a nitro finish. The solvent is toxic, so keeping your guitar and your hands clean after playing is very important.
The solvent in nitrocellulose also reacts poorly to certain compounds, like rubber. This can lead to guitar stands causing damage to a guitar unless the stand has been treated so that the rubber can’t come into contact with the nitro finish.
This has led to nitro becoming less and less popular over time. The health risks and environmental impact are starting to outweigh the tonal benefits of nitro finishes.
Polyurethane, or poly, is a plastic-based finish first introduced in the 1950s. It has become increasingly more popular than nitrocellulose over the years for a number of reasons.
Unlike nitro which requires several layers, polyurethane becomes glossy and even after only two layers. It is also much cheaper, and most importantly, much safer than nitro.
In terms of protection, poly is also very tough while also being relatively lightweight compared to nitro. It is highly resistant to humidity and changes in temperature, making it wear much slower.
This protects the wood better and requires less frequent maintenance. However, poly finish is harder to repair and needs to be done professionally to ensure its durability and even application.
As for the looks, poly is also a bit more versatile with different types available. Many guitars are given a thicker gloss finish, but a thinner satin finish can also be applied for a less glossy, more matte type of look.
The main drawback of poly is that it doesn’t ‘breathe’ quite as much as nitro. This is because poly hardens and tightens quite a bit, reducing the natural resonance of a guitar’s tonewoods.
This leads many guitarists to prefer nitro finishes for its ability to maintain the natural tone of the guitar. Poly is considered a nice middle ground between nitro and the next entry on this list.
Another plastic-based finish, polyester is one of the most modern forms of guitar finish. Polyester is also the cheapest and strongest of the three electric finishes.
It is an extremely tough finish that is very resistant to humidity, temperature, scratches, etc. This toughness means that polyester can protect a guitar almost indefinitely.
Polyester is also highly regarded for how well it handles color. Guitars treated with a polyester finish have very sharp, vibrant colors. Its durability also means that the color won’t fade much if at all over time.
Its hardness does come at a cost, however. Polyester isn’t a very porous material and is often applied in very thick layers. This not only adds quite a bit of weight to the instrument but also affects its resonance.
Polyester doesn’t allow the wood much room to ‘breathe’, reducing the natural resonance of the tonewoods. Guitars with polyester finishes have their tone defined much more by their pickups than by their wood.
These guitars are often seen as cheap-sounding. Most guitarists would rather sacrifice protection for tone instead of the other way around. Although, in a blind test, most guitarists probably wouldn’t be able to notice the difference between a polyester and a polyurethane finish.
At the end of the day, while the finish on a guitar can affect the tone of a guitar, most guitarists either don’t notice or don’t care. The real draw is in the look, the first thing you notice in a guitar and the thing that makes you think “That’s the one I want.”
Regardless of the importance you place on a guitar’s finish, it is still worth understanding why there are different types and what each offers.