We’ve been through quite the journey exploring tonewoods…
From the responsiveness of softwood soundboards (Part 1) to the resonance of hardwood backs and sides (Part 2) and the tactile influence of fingerboards (Part 3), we’ve seen how tonewood choices shape a guitar’s voice and feel.
In this final part, we answer the question many experienced luthiers are asking…“What’s next?”
How is the science of tonewoods evolving?
What’s new in the world of tonewoods?
How does sustainability ensure that future generations can continue building exceptional instruments?
Modern Innovations and Sustainable Approaches
Acoustic guitar building has always embraced tradition, but tonewoods today also benefit from advanced science, specific data, and material engineering. The goal isn’t to replace the magic of wood; it’s to understand it better, use it responsibly, and preserve access to exceptional tonewoods for the decades ahead.
As Nully puts it:
“As a builder, I still rely on my intuition and my feel. The science just changes how I approach voicing that top.”
Let’s take a look at the innovations…
Sonic Grading (PRT Q-Tops)
The BING machine used for sonic grading
For centuries, luthiers have relied on intuition—tap tones, flex tests, weight, and feel—to understand the potential of a soundboard. Sonic grading doesn’t replace that instinct; it quantifies it. It brings measurable clarity to the same acoustic properties builders have evaluated by hand for generations.
At Pacific Rim Tonewoods, sonic grading evaluates each top by three core acoustic metrics:
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Density
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Stiffness – Modulus of Elasticity (MOE)
These are the same variables luthiers adjust for when voicing a guitar. The difference is that sonic grading measures them with repeatable accuracy, giving builders a detailed snapshot of how a given top is likely to behave before they carve, brace, or tap it.
The Research Behind the System
Our grading methodology isn’t theoretical; it’s grounded in an extensive, multi-year scientific study aimed at understanding how the acoustic properties of spruce translate to real-world musical performance.
Some key elements of that research include:
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5 years of testing across 6 laboratories on two continents
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18 guitars, all built to identical specifications
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58 trained listeners analyzing controlled recordings
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Collaboration with Dresden Technical University, home to one of the world’s most advanced anechoic chambers and multi-modal acoustic labs
Inside Dresden Tech’s cathedral-sized anechoic chamber—lined with two-meter foam wedges that eliminate all reflections—we recorded guitars whose only variable was the density, stiffness, and damping of each soundboard.
Those recordings were then analyzed in a 360-speaker measurement laboratory, revealing something long suspected but never before proven:
The sonic differences luthiers hear between pieces of spruce correspond directly to quantifiable material properties.
This breakthrough validated the premise behind sonic grading: that measurable traits can predict tonal outcomes with remarkable consistency.
From Research to Real Tools
Using these findings, we developed a rigorous sonic grading process using the BING measurement system. Every top is tested, analyzed, and categorized. More than 50% of tops tested are rejected, meaning only the highest-performing pieces qualify as Q-Tops.
Each one comes with a data sheet detailing its acoustic profile—a level of transparency that gives luthiers more control than ever before.
With this insight, builders can:
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Select tops whose stiffness and damping match their voicing goals
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Predict dynamic range, responsiveness, and projection more accurately
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Reduce variability between instruments
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Build with confidence for one guitar—or the next thousand
Nully has been one of PRT’s sonically graded most outspoken supporters, saying:
“When PRT released the sonically graded Q tops, I was skeptical. But it [the science] continues to blow my mind. I’ve been trying to poke a hole in their theory – with my hand, my weight, and the flex and tap, but the tops are dead on. And that’s really inspired me. It’s been a couple of years since I’ve been dealing with QTops, and every time I get them, it’s like Christmas. It really is the best Sitka.”
From the bench, the difference is immediately noticeable, as Rye explains:
“Absolutely loving the [sonic grading] wood! I just strung up the Gidgee Lutz guitar …could be one of the best sounding instruments I’ve made to date. The natural reverb that I get in my instrument is just accentuated; it’s going to be a special guitar for sure!”
This intersection of research and craft is shaping the future of guitar making. Sonic grading represents a new chapter where tradition, innovation, sustainability, and craftsmanship all converge to support the next generation of instruments.
Thermally Modified Wood (Torrefaction)
Torrefaction or thermal modification changes wood at a cellular level by heating it in a controlled, oxygen-free environment. In this process, volatile compounds are driven out, internal resins crystallize, and the cell walls physically change.
At Pacific Rim Tonewoods, torrefaction isn’t treated as a generic “roasting” process; it’s a carefully engineered sequence refined specifically for tonewood. Rather than blasting wood with high heat, PRT uses precise temperature curves and highly controlled humidity levels to reduce its susceptibility to humidity changes, leading to less shrinking and swelling.
This shift in the wood’s internal chemistry means:
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Soundboards that are more dimensionally stable
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Increased longitudinal and radial stiffness (MOE)
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Decreased density
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Soundboards that are more uniform in color
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Increased Q (diminished damping)
The end result is a top that feels remarkably “played-in” from day one—open, responsive, and stable across humidity swings.
Salvaged and Recovered Woods
Some of the most prized tonewoods today come from environmentally responsible recovery:
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Old-growth redwood from long-abandoned logging sites
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Sinker logs preserved underwater
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Storm-fallen maple and wind-damaged bigleaf trees
Recovered wood often offers exceptional character: tight growth, dark coloration, and impressive resonance. These woods also do their part in protecting standing forests.
Some luthiers frequently talk about how old-growth salvaged sets have a “mature,” “broken-in,” or “alive” quality—attributes tied to centuries of slow growth, mineral uptake, and natural aging. Many describe these tops or backs as unusually responsive or tonally rich compared to contemporary-cut wood.
There’s also a shared sentiment that working with these materials brings a sense of respect and responsibility—turning a fallen or forgotten tree into a world-class instrument feels meaningful, and many luthiers say that energy comes through in the final guitar.
The Future Forest: Growing Tomorrow’s Tonewood
Responsible sourcing isn’t only about protecting existing forests; it’s about ensuring the next generation of tonewood exists at all.
At Pacific Rim Tonewoods, sustainability means looking decades ahead. Through long-term forestry initiatives like Utopia and Siglo, PRT is actively investing in the future supply of instrument-quality wood. These projects focus on cultivating tonewood species under carefully managed conditions, while studying how factors such as site selection, growth rates, climate, and forest management practices influence the structural and acoustic properties that matter to luthiers.
The goal is to grow better tonewood. By combining forestry science with acoustic research, these programs help ensure that future generations of builders will have access to wood that meets the same standards for stiffness, density, stability, and resonance that today’s instruments demand.
For us, Utopia and Siglo reflect a broader shift in how tonewood is approached—from a finite natural resource to something that can be responsibly cultivated, understood, and stewarded over time. It’s a long-term commitment to both environmental responsibility and the continued availability of exceptional guitar wood for the luthiers who rely on it.
Closing Thoughts
The future of tonewood isn’t about choosing between tradition and innovation; it’s about letting them elevate each other.
From torrefaction to sonic grading, from careful forestry to reclaimed old-growth, these advances ensure the guitars built tomorrow can be as inspiring as those cherished today.
If you’d like to explore our most carefully engineered and responsibly sourced tonewoods—including Q-Tops, torrefied tops, and limited salvaged sets, you’ll find them in our tonewood shop and Vault collections.
Explore the full series:
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Part 1 — Softwoods for Soundboards
How Sitka, Lutz, Engelmann, cedar & redwood shape the guitar’s primary voice -
Part 2 — Hardwoods for Backs & Sides
How rosewood, mahogany, maple, koa & others reflect, reinforce & color tone -
Part 3 — Fingerboards & Playability
Ebony, rosewood & maple: where tone meets touch - Part 4 — Science and Sustainability
How tonewood is evolving in the world of guitar building
