About Guitar Finishes
Introduction
The influence of guitar finishes on tone has long been a subject of debate among luthiers, musicians, and enthusiasts. Among the myriad of finishes available, nitrocellulose lacquer has been traditionally revered for its supposed superior acoustic properties, often linked to the concept of the "breathing guitar." This notion suggests that certain finishes allow the wood to resonate more freely, thereby enhancing the instrument's tone. However, scientific scrutiny reveals a more nuanced reality, challenging these widely held beliefs and inviting a reevaluation of the impact of finishes on guitar tone.
In an effort to demystify the effects of guitar finishes, a study conducted by H.P. Stephens examines the vibrational properties of spruce guitar soundboards coated with various finishes, including traditional de-waxed shellac and nitrocellulose instrument lacquer, alongside reactive shellac-based finishes. This research provides a foundation for a scientific exploration into how finishes interact with the wood, influencing fundamental aspects such as the vibrational frequency (f0) and the damping quality factor (Q).
The main goal of this article is to debunk myths surrounding guitar finishes, particularly the alleged superiority of nitrocellulose lacquer, by delving into the scientific principles underlying the effects of different finishes on tone. Through a rigorous examination of empirical data, we aim to shed light on the actual impact of finishes, guiding luthiers and players towards informed decisions based on objective evidence rather than tradition or anecdote.
Background on Guitar Finishes
Guitar finishes have long been recognized for their dual role in both protecting and enhancing the aesthetic appeal of musical instruments. However, beyond their visual and protective functions, finishes also hold the potential to influence the acoustic properties of an instrument. This relationship between finishes and acoustics forms the basis of an intriguing area of study within the field of lutherie.
Traditionally, guitar finishes have been categorized mainly into two types: evaporative and reactive. Evaporative finishes, such as de-waxed shellac and nitrocellulose lacquer, dry by solvent evaporation, leaving behind a film that can be relatively thin and may have a certain degree of porosity. On the other hand, reactive finishes, which also include shellac-based types, undergo a chemical curing process after the solvent evaporates, leading to a more durable and potentially thicker film.
The distinction between these two categories of finishes raises significant questions for guitar makers and enthusiasts alike. One of the most pressing inquiries is whether the different physical and chemical characteristics of evaporative and reactive finishes lead to noticeable differences in the vibration properties of the wood they cover. Specifically, the study highlighted in the introduction segment aims to shed light on this matter by comparing the effects of these finishes on the vibrational behavior of spruce, a commonly used wood for guitar soundboards.
Understanding the impact of various finishes on the acoustic properties of guitars is not just a matter of scientific curiosity but also has practical implications for the design and construction of these beloved instruments. As we delve deeper into the nuances of guitar finishes, we uncover the complex interplay between materials, craftsmanship, and sound, a relationship that continues to fascinate and challenge luthiers and musicians alike.
Scientific Principles of Sound and Material Interaction
Understanding the scientific principles behind sound and material interaction is crucial in evaluating the impact of different finishes on a guitar's tone. This section explores how sound waves interact with guitar finishes and how these interactions might affect the instrument's acoustic properties.
Vibrational Energy Transfer: At the heart of a guitar's sound is the transfer of vibrational energy from the strings to the air, primarily mediated by the guitar's body and soundboard. The efficiency and character of this energy transfer are influenced by the material properties of the wood and the finish applied to it.
Material Damping: Different materials and finishes exhibit varying degrees of damping, which affects how they absorb and dissipate vibrational energy. A finish that adds significant damping can reduce the vibrational energy of the wood, potentially "muting" the instrument's resonance and sustain.
Acoustic Impedance: The acoustic impedance of a material describes its resistance to sound wave propagation. Finishes can alter the surface acoustic impedance of the guitar's body, affecting how sound waves are reflected or absorbed, thereby influencing the tone.
Microscopic Interactions: On a microscopic level, the finish affects the wood's surface properties, such as roughness and porosity, which in turn can influence how sound waves interact with the instrument's surface. These interactions can subtly alter the timbre and resonance characteristics of the guitar.
Perceptual Effects: Beyond the physical interactions, the perception of tone is subject to psychoacoustic effects. The listener's brain interprets the complex mixture of harmonics, overtones, and resonances, which are all influenced by the guitar's material properties and finish.
Vibrational Properties of Wood
The vibration of guitar soundboards is central to sound production in both acoustic and electric guitars. The fundamental vibrational frequency (f0) of the wood is a critical factor, as it determines the resonance characteristics of the instrument. Finishes can alter this vibrational frequency by adding mass and changing the surface properties of the wood. Studies, such as the one conducted by H. P. Stephens, have investigated the impact of various finishes, including de-waxed shellac and nitrocellulose lacquer, on the vibrational properties of spruce, a common material for guitar soundboards.
Finish Types and Their Effects
Evaporative Finishes: Traditional finishes like nitrocellulose lacquer and de-waxed shellac fall into this category. They dry by solvent evaporation, leaving behind a solid film that can influence the wood's vibrational behavior. The application of these finishes has been shown to affect the fundamental vibrational frequency of spruce soundboards, an essential aspect of their tonal impact.
Reactive Finishes: Modern finishes, such as certain shellac-based formulations, cure through chemical reactions that occur after solvent evaporation. These finishes potentially offer a more durable coating but also impact the wood's vibration differently than evaporative finishes. The study by Stephens explores these differences, providing insights into how reactive finishes compare to their traditional counterparts in altering wood's vibrational properties.
Electric Guitars Consideration
While the primary focus might be on acoustic instruments, it's worth noting that the physical properties of electric guitars, including their finishes, can also influence tone. The body's resonance, affected by the finish, can interact with the electric signals generated by the pickups, subtly coloring the amplified sound. This interaction is less direct than in acoustic guitars but still relevant for those seeking to understand the nuances of electric guitar tone.
A significant part of this discussion involves debunking myths surrounding guitar finishes, particularly the notion that certain finishes like nitrocellulose allow the guitar to "breathe" and thus produce a superior tone. Scientific analysis, such as the vibrational studies mentioned, provides a more nuanced understanding, showing that while finishes do impact vibrational properties, the effects are complex and not solely attributable to the finish type. This knowledge challenges the traditional hierarchy of finishes and encourages a more informed approach to selecting and evaluating guitar finishes.
In summary, the interaction between sound waves and guitar finishes is a complex interplay of material science and acoustics. Understanding these principles helps in making informed decisions about finishes, whether for preserving traditional tones or exploring new sonic possibilities in guitar design.In the broader context of "breathing guitars" and the supposed superiority of nitrocellulose finishes, it's essential to approach claims with a critical scientific perspective. While nitrocellulose and other traditional finishes may have less impact on the wood's natural resonance compared to some modern, heavier finishes, the differences in perceived tone can be subtle and subject to individual interpretation. This section aims to demystify the role of finishes in sound production, providing a foundation for understanding how material choices contribute to the unique voice of each instrument.
In the realm of guitar construction, few topics are as contentious or surrounded by myth as the impact of finishes on an instrument's tone. A pervasive belief among many musicians and luthiers is that certain finishes, particularly nitrocellulose lacquers, allow the guitar to "breathe" more freely, thereby enhancing its tonal qualities and resonance. This section aims to address these beliefs head-on, armed with scientific evidence and analyses to separate fact from folklore.
The "Breathing" Guitar Myth
The concept of a "breathing" guitar suggests that the finish applied to the wood impacts its ability to resonate, with thinner, more permeable finishes like nitrocellulose purportedly allowing the wood to vibrate more freely and produce a superior tone. This notion is deeply ingrained in guitar lore, often leading players and builders to favor traditional finishes despite their drawbacks in durability and environmental impact.
Let’s also change the point of view a little bit. If the ultimate goal for the best tone was to have a perfectly breathing, living and free guitar, would'nt oiled and non finished guitar considered vastly superior ? And why would’n builders and players choose oil finishes since decades if that was a significant criteria ?
Scientific Findings on Finish Impact
Recent studies, including an in-depth analysis by H.P. Stephens, challenge the traditional views on the impact of finishes on vibration and tone. The study meticulously examined the effects of various finishes, including dewaxed shellac, nitrocellulose lacquer, and modern reactive finishes, on the vibrational properties of spruce, a common tonewood for guitar soundboards. The findings reveal that both evaporative (e.g., nitrocellulose) and reactive finishes, when applied over the same sealer, produce equivalent changes in the fundamental vibrational frequency (f0) and damping quality (Q) of the wood. Notably, the sealer alone induced significant changes, while the type of top coat finish did not materially alter the wood's vibrational behavior, debunking the notion of nitrocellulose's supposed superiority in preserving the wood's natural resonance.
It appears that the only parameter that we can retain as significant isn’t material, but coat thickness. You would’nt play a guitar that has a 3mm nitrocellulose topcoat over a 0.5mm polyurethane finish
Electric Guitars
While the discussion often centers around acoustic guitars, it's crucial to extend this analysis to electric guitars, where the choice of finish is predominantly aesthetic, given the minimal impact on the instrument's electronically amplified sound. Unlike their acoustic counterparts, electric guitars rely on pickups to convert string vibrations into electrical signals, making the wood's vibrational characteristics less critical to the overall sound. This reality further diminishes the argument for "breathing" finishes in the context of electric guitar construction.
The myth of the "breathing" guitar and the alleged superiority of traditional finishes like nitrocellulose lacquer is not supported by scientific evidence. Comprehensive studies demonstrate that the type of finish has a negligible impact on the wood's vibrational properties, challenging long-held beliefs and encouraging a more informed approach to guitar finishing. This evidence-based perspective not only informs the choices of builders and players but also opens the door to more sustainable and practical finish options, marrying tradition with innovation in the art of guitar making.
Effects of Different Finishes on Tone
The impact of guitar finishes on tone has been a subject of considerable debate among luthiers, musicians, and enthusiasts. This section draws upon scientific studies, including the investigation of the effects of sealer and four different finishes on the vibrational properties of spruce for guitar soundboards, to shed light on how various finishes influence the sound of a guitar.
Scientific Findings
The study highlighted in the Savart Journal explored the effect of de-waxed shellac, nitrocellulose instrument lacquer, and two reactive shellac-based finishes on Sitka spruce test bars. The research found that the sealer alone could significantly alter the fundamental vibrational frequency (f0) and the damping quality factor (Q) across different grain orientations. Specifically, the sealer decreased f0 along the grain and increased it across the grain, while reducing Q in both orientations. When top coats were applied, only the along-grain bars showed a decrease in f0, but all top coats increased Q for the along-grain bars after curing for seven weeks, with no significant effect on the cross-grain bars. Importantly, statistical analysis demonstrated that all top coat finishes had equivalent effects on the vibrational properties of the spruce bars after the curing period
Oil Finishes
In addition to the more traditional lacquers and sealers, oil finishes are another option that luthiers may consider. Oil finishes, such as linseed or tung oil, penetrate the wood to provide protection while leaving a more natural feel to the instrument. These finishes are often praised for their ease of application and repair, and for not adding significant mass to the wood, potentially allowing for more natural vibration and resonance. However, the scientific impact of oil finishes on tone is less documented, and any perceived differences in sound quality may be subtle and subjective.
Electric Guitars
While the focus of the aforementioned study was on acoustic guitar soundboards, the principles of finish effects apply to electric guitars as well, albeit in a different context. Electric guitars rely more on their electronic components (pickups, amplifiers, etc.) for sound production, but the wood and its finish can still influence the instrument's overall tonality and sustain. For electric guitars, finishes might affect the body's resonance, which in turn can subtly color the sound that the pickups translate into an electrical signal.
The scientific exploration of guitar finishes and their effects on tone reveals a complex interaction between the material properties of the finish and the vibrational behavior of the wood. While traditional finishes like nitrocellulose and modern reactive finishes have been shown to have equivalent impacts on the vibrational properties of spruce bars, the choice of finish—whether for an acoustic or electric guitar—still holds aesthetic, practical, and potentially tonal significance. As the guitar world continues to blend tradition with innovation, the ongoing study of finishes and their effects on tone remains a vital part of the conversation surrounding guitar construction and sound quality.
Innovations and Future Directions
The guitar industry is witnessing a period of innovation and exploration, especially in the realm of finishes, as luthiers and manufacturers seek to balance aesthetic appeal, durability, and tonal influence. The future of guitar finishes is likely to be shaped by advancements in materials science, environmental sustainability, and the ongoing quest to enhance musical expression through technological innovation.
Innovations in Materials
Recent years have seen the development of new finish materials that offer improved durability, ease of application, and minimal impact on the tonal qualities of the instrument. Water-based finishes, for example, have gained popularity for their lower environmental impact and reduced health risks during application. These finishes dry faster and emit fewer volatile organic compounds (VOCs) than traditional solvent-based finishes, making them a more sustainable choice for both manufacturers and the environment.
Enhancing Tonal Characteristics
The exploration of finishes that can positively influence or at least preserve the natural tonal characteristics of the wood is an ongoing pursuit. Innovations in thin-film finishes and nanotechnology coatings offer the potential to protect the instrument without significantly dampening its resonance. These advanced coatings are designed to be ultra-thin, allowing the wood to vibrate more freely while still providing adequate protection against moisture, temperature changes, and wear.
Customization and Personalization
Advancements in finishing techniques are also enabling greater customization and personalization of instruments. From high-definition digital printing to intricate laser etching, players can now customize their guitars with detailed artwork, patterns, and textures that reflect their personal style without compromising the instrument's structural integrity or sound quality.
Environmental Sustainability
As the guitar industry continues to focus on sustainability, the development of eco-friendly finishes that do not harm the environment or deplete scarce resources is becoming increasingly important. The use of naturally derived resins, oils, and waxes that are biodegradable and non-toxic is on the rise, offering luthiers and manufacturers an opportunity to contribute to conservation efforts while still producing high-quality instruments.
The Role of Research and Development
The study highlighted in the Savart Journal illustrates the kind of research that is pivotal in advancing our understanding of how finishes affect the vibrational properties of wood. Such studies are crucial in debunking myths and guiding the development of new finishes that meet the evolving needs of musicians and the industry.
Future Directions
Looking ahead, the intersection of traditional lutherie with modern materials science and environmental ethics is set to define the future of guitar finishes. Continued research into the impact of various finishes on the tonal qualities of instruments, coupled with innovations in sustainable materials and application techniques, will shape the next generation of guitars. As we move forward, the challenge will be to honor the rich heritage of instrument making while embracing the possibilities that new technologies and materials bring to the art of guitar construction.
Conclusion
In concluding our exploration of guitar finishes and their impact on tone, it's evident that the scientific community has begun to unravel the nuanced relationship between finish types and the vibrational properties of guitar woods. A pivotal study highlighted in our discussion found that various top coat finishes, including both evaporative and reactive types, yield equivalent changes in the fundamental vibrational frequency and damping qualities of spruce, a commonly used tonewood for guitar soundboards. This finding challenges the long-held belief in the superiority of certain finishes, such as nitrocellulose lacquer, for enhancing an instrument's tone.
The conclusion drawn from this and similar studies is twofold: firstly, that the type of finish, whether traditional or modern, does not singularly dictate the tonal quality of a guitar. Both the sealer layer and the chosen top coat have measurable effects on the wood's vibrational properties, yet these effects do not necessarily translate to a superior tonal outcome for any one finish type. Secondly, the notion of a "breathing guitar," wherein the finish significantly allows the wood to resonate more freely, seems less about the porosity or flexibility of the finish and more about the overall interaction of the finish with the wood's natural vibrational tendencies.
This scientific perspective does not diminish the artistry or craftsmanship involved in selecting and applying finishes to guitars. Instead, it encourages a broader understanding and appreciation of how various factors, including the type of wood, the construction techniques, and yes, the finish, collectively contribute to the instrument's final sound. As we move forward, the integration of scientific insights with traditional lutherie practices promises to enhance our ability to craft instruments that not only meet the aesthetic and protective needs but also fulfill the acoustic potential inherent in each piece of wood.
