A Galloup guitar made from paulownia.
Guitars priced between $1,500 and $4,000 typically utilize domestic woods or other widely accessible alternatives that provide excellent value. However, in recent years, sustainability has become an increasingly critical concern regarding the sourcing of these natural resources. We are committed to ensuring that the materials we select not only deliver superior sound but also align with sustainable practices, helping to preserve the environment for future generations of musicians.
Over the years, I’ve encountered difficulties with alternative, sustainable soundboard options. That is, until I took part in the paulownia experiment initiated by World Tree, an environmental organization “focused on nature-based solutions to some of our biggest global challenges.” This project highlighted wood from the fast-growing paulownia tree, which was cultivated by former President Jimmy Carter. Initially, the prospect of using paulownia appeared impractical. Yet, upon further analysis, we recognized its potential as a viable substitute, though some of its material property characteristics, such as damping and admittance, still require further testing.
Many luthiers understand traditional soundboard materials well. Despite this knowledge, integrating new tonewoods into our repertoire can be an arduous process. Fortunately, advancements in wood testing technology have significantly expedited the evaluation process. Currently, for the assessment of wood, I use the Acousonix Sonic Calculator, a handheld application that enables me to input various wood-property parameters for a thorough evaluation. Upon entering the data, the application delivers a precise rating, considers multiple factors, delineates the wood's sonic characteristics, and then specifies its best use applications.
Fig. 1
My Acousonix analysis of paulownia indicates that its 11.3 sonic rating makes it unexpectedly well-suited for use as a soundboard (see Fig. 1). As my builds with this material progressed, the results were exceedingly promising. Paulownia features well-rounded tonal characteristics, exhibiting a rapid response with a seemingly high admittance, which indicates a lower damping factor. Another noteworthy aspect of paulownia is its sustainability: The tree reaches full maturity in approximately 12 years. Upon harvest, a new sapling can be replanted in the same root system, allowing for accelerated mature growth in around seven years. This cycle can be repeated multiple times, establishing paulownia as a highly renewable resource. But unlike typical spruce, which commonly yields eight to 11 growth rings per inch, paulownia’s growth rings come in at around three to four per inch. But don’t let this fool you. Despite its non-traditional appearance, paulownia has a reputation for being stable and warp-resistant (see Fig. 2).
Fig. 2
“Another noteworthy aspect of paulownia is its sustainability: The tree reaches full maturity in approximately 12 years.”
While testing paulownia for guitar making, we observed that this species yields a highly responsive instrument. It offers a fast musical response similar to many late-1930s Gibson J-35s I have played. It exhibits a quick response with a lower fundamental and a pleasant decay. But, due to its lightweight—around 5 grams per cubic inch—it tends to exhibit lower headroom. Thus, despite being a powerful and enjoyable guitar to play, it tends to distort when pushed to higher volumes. In its defense, most players commonly don’t play hard enough to reach these limits.
Ultimately, the tests I conducted affirm its potential as a substitute tonewood for guitars, possessing desirable acoustic properties. While paulownia has historically been utilized in instruments like the Japanese koto, it stands to reason that the acoustic guitar market should explore this avenue further. To prove a point, we used paulownia for the top, back, sides, bracing, and neck, with the total price tag for all tone woods used coming in at around $70. So, given its low cost, stability, availability, and the grower's commitment to environmental sustainability, paulownia is a resource deserving of serious consideration.
For more information about World Tree, visit worldtree.eco, and to learn more about the Acousonix Sonic Calculator, visit acousonix.com.
