When it comes to guitars, the choice of finish plays an important role in not only protecting the instrument but also enhancing its aesthetics, so knowing which to choose for your guitar might be confusing given how many options are available.
From classic nitrocellulose lacquers to modern polyurethane coatings, and from traditional oil finishes to elegant French polish, each type of finish brings its own set of characteristics and considerations. They also bring their own sets of pros and cons which could be the deciding factor in what method you decide to finish or refinish your guitar with.
Nitrocellulose lacquer guitar finishes
Nitrocellulose lacquer, often simply referred to as "nitro," remains a popular choice for its distinctive qualities and length of use. This type of finish provides a glossy sheen and dries quickly, making it an attractive option for those seeking vibrant colours and a reliable outer coating.
Given that this finish has been in use since the advent of modern guitar production, a lot of local guitar technicians and local guitar repair businesses will offer this service.
Moreover, nitro finishes offer versatility; they can be applied without colour, yielding a high-gloss natural finish that doesn't require the sometimes undesired thickness of polyurethane coatings. However, despite its appeal, nitrocellulose lacquer does come with a drawback in terms of durability.
Unlike polyurethane finishes, nitro has a propensity to age more visibly, developing a charmingly weathered appearance over time—a feature some players appreciate for its vintage allure. It’s not an inevitability that a nitro finish will craze over time, but it can happen and that should also be a consideration.
Nitrocellulose lacquer is essentially a guitar finish that is highly responsive to its environment, sometimes to the extreme. For example, exposure to rubber or foam can lead to a phenomenon known as "nitro burn," where contact with these materials causes the lacquer to melt and reform, leaving behind unsightly marks. Understanding these characteristics is crucial for maintaining the pristine appearance of a nitro-finished guitar.
Acrylic lacquer finishes
Acrylic lacquer finishes offer an alternative to nitrocellulose lacquer, boasting their own set of characteristics and advantages. While acrylic lacquers are generally less reactive than their nitro counterparts, it's important to note that they're not entirely non-reactive. Acrylic finishes can still exhibit interactions with certain materials, such as lacquer, leading to what's commonly known as "burn-through."
One notable advantage of acrylic lacquer finishes is their affordability relative to nitrocellulose lacquers. This cost-effectiveness makes them an appealing option for those seeking a quality finish without breaking the bank. Additionally, acrylic lacquer finishes often boast durability comparable to nitrocellulose lacquers, providing adequate protection against wear and tear over time.
However, due to the popularity of nitro among luthiers and guitar technicians, acrylic lacquer is often less readily available than nitrocellulose lacquer. This scarcity should be factored into one's consideration, particularly if they anticipate the need for touch-ups or refinishing work in the future.
Polyurethane finishes
Polyurethane finishes have become the go-to choice for many modern guitars, owing to their cost-effectiveness and suitability for mass production in factory settings. One of the key advantages of poly finishes lies in their exceptional durability and resistance to wear and tear. Their tough, hard-wearing nature makes them ideal for players who prioritise longevity and protection, or who know their usual gigging environment.
Moreover, polyurethane finishes often exhibit a very glossy appearance, lending guitars a sleek and polished look. Additionally, their low reactivity allows for the use of a wide range of cleaning products without fear of damage. Where you would get nitro burn on a vintage guitar or on a guitar that has been refinished in nitro, no such risk applies to polyurethane; it’s incredibly tough and hard-wearing.
One thing to address about poly - there exists a pervasive myth claim among purists - be that your local guitar tech or local luthier - that polyurethane finishes negatively impact a guitar's tone. While theoretically plausible, this claim lacks empirical evidence to support its validity. In reality, the alleged tonal effects of poly finishes are often overstated, especially in the case of solid-body guitars where any impact is typically imperceptible. For archtop and acoustic guitars, it’s often stated that the wood ‘can’t breathe’ and this affects the tonal quality. To this, I simply ask you to run your finger on the underside of your archtop or acoustic tonewood through the f-hole or soundhole. Feels unfinished, right? Yeah, I thought so.
I appreciate the argument that effectively wrapping an acoustic guitar in a plasticine finish will affect its tone - there’s a chance this could happen. But is it an absolute truth that poly as a finish ruins tone? Absolutely not. If anything, its durability will help protect your tonewood from more elements than any other guitar finish.
Oil finishes: Gun stock, tung, and Danish oil
Oil finishes offer a distinct approach to guitar refinishing, with variations such as gun stock oil, tung oil, and Danish oil each offering unique characteristics.
Gunstock oil, primarily composed of boiled linseed oil, provides a traditional option known for its deep penetration and protective qualities. The luthier's choice is TruOil, which is known to be easy to apply and long-lasting.
Tung oil, derived from the stone of the fruit of the tung tree, offers a natural finish with excellent water resistance and durability. It’s also very long-lasting, and readily available.
Danish oil, a blend of various oils and resins, combines the benefits of both penetration and surface protection, but can sometimes come with a slight tint to it. This can be very nice if paired with the right wood - Swamp Ash for example - but should be a consideration for the finish because it will produce a warmer tone.
Despite their differences, the application process for these oil finishes remains largely similar. It typically involves sanding the guitar's surface, applying the oil in thin coats with a tack cloth, allowing it to penetrate the wood, and then wiping off any excess.
Subsequent coats can be applied as needed until the desired finish is achieved, with drying times varying depending on the specific oil used. Buffing these oils produces a gloss finish that will rival the glossiest most well-polished polyurethane.
French polish guitar finishes
French polish finishes are predominantly associated with classical guitars, renowned for their elegance and traditional craftsmanship. This meticulous technique involves applying thin layers of shellac dissolved in alcohol to achieve a highly polished surface.
The process begins with preparing the guitar's surface through sanding and pore filling, followed by the application of a base coat of shellac. Subsequent coats are applied using a pad made of cloth or cotton wool, with each layer meticulously rubbed into the wood to build up a smooth and glossy finish. Between coats, the surface is gently rubbed with a lubricant such as oil to prevent sticking.
French polish finishes require patience and skill, as achieving the desired level of glossiness may involve numerous applications and meticulous buffing. However, the result is a stunningly beautiful finish that enhances the natural beauty of the wood and is revered for its traditional craftsmanship.
Finishing isn’t the end of your journey…
Finding the right finish for your guitar is just the beginning of the journey. If you’re building your guitar from a kit or from scratch, it can be the starting point where the only thing left to do is get it wired up and get playing!
And if you’re considering a change to your guitar’s finish, Kelly at Alchemy Instruments has the time and expertise to help you choose the best option for your instrument. Feel free to get in touch if you have any questions about guitar refinishing.
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