2012年5月2日星期三

Maple Offers Figures Fantastic for Furniture & Specialty Items

Defined as a deviation in direction from straight grain in one or more growth rings of the tree, maple figure comes is many forms. “Figure may be caused by compression from large limbs, vine constrictions, injury, genetics, insect infestation, growth conditions and numerous other causes, some known while others remain a mystery,” said Ang Schramm, Technical Services Director, Columbia Forest Products.

This special form of growth occurs in only 2 to 5 percent of all maple logs, according to Veneers, A Fritz Kohl Handbook. The occurrence applies to both hard and soft maples.

Although bird’s-eye is the most well-known, maple also yields a range of other figures. Curly figure, said Schramm, occurs when the grain, normally oriented in a generally straight line parallel to the upward growth of the tree, becomes compressed in a more-or-less washboard pattern due to one of the causes listed above. “During processing into veneer or lumber, the knife or saw will cut across these regions of the log, producing a pronounced striped appearance across the grain. Because the cut crosses the wavy grain at a somewhat radial approach, it leaves a repeating pattern of end-grain, flat-grain, end-grain, giving the resulting surface an almost iridescent three-dimensional look that is greatly enhanced with the application of finish materials.”

Curly figure may be categorized into non-specific groups, with names like cross bar, flair, tiger stripe, mottled, quilted, or fiddleback, depending on the intensity and relative population on a given surface. Generally speaking, Schramm said, cross bar and flair figure occur in isolated regions on the surface. Tiger stripe is used to describe figure that is boldly pronounced on the radial plane and distributed over a high percentage of the surface. Fiddleback, named for its association with the backs of fiddles and stringed instruments, is usually much smaller in size relative to tiger stripe.

Uses for curly and other maple figures include: high-end residential and office furniture, wall panel systems, store fixtures, inlay and musical instruments. Figured maple also is used in specialty pieces. Ken Wheeler, founder of Renovo Bikes, Portland, OR, uses curly maple in one of the more unusual applications.

The company uses figured eastern maple in its performance bikes. “It is typically used in the center as an accent with other woods, like bubinga,” Wheeler said. “For our application in our performance bikes, it isn’t just about the look, it is how the bike will hold up and perform. Western maple has a gorgeous color and curly figure, but it is too soft for our needs,” he added.

In addition to hardness, aesthetics is also important. Schramm recommended obtaining a sample or photo approval whenever specifying wood with these characteristics. For example, he said, with bird’s-eye maple the population, size and dimensionality of the “eyes” determine whether it is considered valued or undesirable. “I would caution anyone specifying bird’s-eye to approve samples as agreed upon by buyer and seller before purchasing.”

Caution should also be taken when working with the wood. “Because the grain undulates so that end grain is present, finish has a tendency to saturate those areas, often creating a splotchy, washed out effect unless careful preparation to include a wash coat or glue sizing is included in the finish process,” Schramm said. “The abrupt grain direction changes also lead to saw and machine chipout that can be addressed to a great extent by machining in the direction of the grain, use of multiple cutting surfaces on shaper tooling, along with appropriate tool speeds and feed rates.”

But when properly machined and finished, he added “figured maple will always create a breath taking work of art that seems to pop out at the admirer.”

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