Today we take a look deeper into the relatively new industry term of "roasted" woods being used in guitars. "Roasted" wood is industry jargon for wood that has been thermally modified. I recently traveled to Superior Thermowood, a facility nestled among the frozen forests of Northern Minnesota. It is here that guitar parts for companies such as Gibson and Fender come to be thermally modified. I went there to learn about what exactly roasted wood is and what it means for guitarists and the future of the industry. I found the process of thermal modification and its practical and tonal implications to be an exciting new frontier for luthiers and guitar nerds alike.
Roasted wood is relatively new technology in the guitar industry but it has already unearthed a lot of great discoveries which paint a bright future for many guitarist's quest tone. What if we could build a guitar that comes off the luthier's bench or assembly line sounding exactly like a rare (insert coveted acoustic here)? What if we could make renewable woods like pine, spruce, or cedar sound exactly like or better than the more coveted exotic or endangered woods? The answer to both of these questions may lie in thermal modification.
What is "Roasted" wood?
Roasted wood is often thought to mimic the sound of vintage wood. As wood ages, it dries out. So starting out with wood that is already dried out. The process draws out the water out of the cells of the wood, leaving behind a bit for dried sap. Nearly all brands now offer roasted guitars - Martin Taylor, Fender, and Gibson.
The roasting process occurs inside a kiln - which controls temperature and humidity. The kiln at Superior Thermowood is massive. Inside this kiln is where heat and humidity, which are both closely monitored by computer, work in tandem to dry out the wood to a desired humidity level. Each wood has a specific variation of the process meant to achieve a certain humidity level, and visual aesthetic.
Thermally modified wood is used for all sorts of other applications, typically outdoor applications like decking since the wood is water resistant. This has practical uses in the guitar world - for example a maple neck that has been roasted will be more resistant to humidity changes. The same effect has been used in the past by using chemicals but the thermal modification process used at Superior Thermowood uses no chemicals. In fact, the company has won awards from The University of Minnesota for their environmentally friendly roasting process.
What does this mean for the guitar industry?
Roasting wood tends to bring out and enhance the natural beauty of the woodgrain. The color of woods can be manipulated as well. In addition to the visual aesthetic, thermal modification also enhances certain tonal qualities in the wood. It is often thought to mimic the sound of vintage wood. Whether or not roasted wood perfectly replicates the vintage sound is a hotly debated issue. The idea behind lowering the humidity level of the wood is to speed up the natural drying process. Low humidity levels are often one of the main factors contributing to the "vintage tone". One could assume that if roasted wood can perfectly mimic the sound of a vintage guitar, it could potentially drive the price of vintage guitars down. During the tour, we were able to compare pine tops that had been thermally modified against its traditional counterpart. The thermally modified top was much brighter and resonant. Another secondary effect of roasting guitars parts is that they come out lighter due to the moisture (water weight) being drawn out of the wood.
I would be remiss in my journalistic duties if I didn't mention the one obvious con to thermally modified wood - the price. Many of us who have looked into purchasing a "roasted" guitar will note the drastic spike in price when the word roasted is used. It should also be noted that different brands will use different roasting processes.
Walking around the compound at Superior Hardwood and seeing stacks of ash body blanks - ready to be sent off to Fender, Stacks of Rosewood fretboards ready to be shipped off to Gibson, its enough to have any guitar geek or DIY luthier in awe. The folks who work at ST are constantly experimenting with various woods and settings in the kiln. Somewhere between lumberjack and mad scientist, the folks at Superior Thermowood may very well hold the key to your "holy grail" tone.