What distinguishes 'instrument grade' wood? - Dec 2002
Instrument grade tonewood, differs from other woods in its consistency, density, strength & appearance. Tonewoods include the spruce & cedar most typically used for the tops of stringed instruments, the maple, mahogany, rosewood, walnut & cherry used for the necks, backs & sides, fingerboards & bridges. Tonewood is quartersawn - split through the center of a log, perpendicular to the tree’s growth rings. Quartersawing produces fewer boards than cutting logs in parallel slabs (as construction lumber). But quartered wood has straight, even grain with enough strength to withstand string tension & enough flexibility to vibrate freely.
Wood suppliers cut the wood into thinner wedges & stack it to air-dry for at least 4 years. Builders split the wedges in half & ‘book-match’ the two halves to make instruments (smaller instruments’ backs are sometimes one piece). Wood suppliers grade wood quality according to grain straightness & tightness (5 grains/inch is very wide, 20 grains/inch is very tight), run-out (wood grain ‘runs out’ of the board when the wood is cut at an angle relative to the plane of grain direction; run-out diminishes wood’s tonal transmission). In woods for the back, neck & sides of an instrument, the amount of figure (dramatic color variations & iridescence within the wood) is a very important aesthetic, not tonal issue. In woods for tops, clarity, uniformity of color & run-out are critical issues. The only color variation commonly accepted in the top wood is ‘bear-claw’ figure - swirls of parallel light-color patterns that bear claws might make.
Grading for tonewood for tops (spruce, cedar, fir) includes AAA/AAA-plus, AA, A & lower. A & low-A grade wood has some grain irregularity & ‘wiggle,’ wide grain spacing, moderate run-out, color variation & knot shadow. AA grade wood, prevalent in large-scale manufacture of good-quality guitars, has medium-to-tight grain with little run-out & slight color variation. AAA grade is slightly less perfect than AAA-plus; both grades have tight-to-very-tight, very straight grain with no run-out or color variation.. Adirondack spruce, the strongest, stiffest, lightest of all spruce species, is the most rare, sought-after spruce on Earth. Sitka, Engleman & European spruce are also excellent instrument-top tonewoods.
In woods for the neck, back & sides of instruments grading has different priorities. Straightness of grain (strength) is paramount for necks; figure, while prized,is not essential. Maple & mahogany are common neck woods. For backs & sides, figure such as flame, quilt, burl & birdseye speckle are highly prized– as is significant color variation. Grades of 3A, 4A & 5A indicate the amount of figure & visual beauty of maple, mahogany, East Indian rosewood, walnut & cherry used in backs & sides. Flamed maple is completely dominant in violins. In guitars, Brazilian rosewood, like Adirondack spruce, is the ‘Holy Grail’ for many players.
What can I do.
If you are interested in learning more about tonewoods, where they come from & their grading, stop by the store. We will tell you what we know & give you references for more detailed information.