Choosing and Producing
Wood for Lutherie
Some of the subtler elements of a stringed instruments are determined in selecting the wood for the top and back.
The tonewood pieces used are sawn from instrument-grade black walnut (for backs) and redwood (for tops). We begin by sawing pieces of quarter sawn 2"x4" or 2"x6" wood into slabs about 34" long, 4-to-6" wide, and about .150" thick. Neighboring slices are then paired into "bookmatched sets". These sets are called "Bookmatched" because when you open them side by side (like opening a book) their grains are twins of each other.
These pairs are then joined. Joining is the process of making their matching edges perfectly straight and gluing the edges together to make a board twice as wide. (Actually, you want a little concavity between them, so that when you clamp them together, the ends are under more pressure that the center. If the center are under more pressure, the ends will have a little tendency to release from the glue joint, resulting in a joint that is not as strong as otherwise.) Now we have boards that are twice as wide as the original plank, and the grain pattern is quarter sawn, and symmetrical about the centerline.
Next, these "bookmatched" tops and backs are planed down to a thickness of about .085 inches. Then they are stored in the shop for several months at 35-45% humidity, to get them down to their final moisture content. Then they are ready to be evaluated for their acoustic properties.
In an utterly quiet room each candidate top and back is carefully evaluated for its musical potential. Many pieces will be judged, to produce a top and back that will be tailored to the requirements of the instrument to be constructed.