African hardwood causes sticky dilemma

THOUGH acclaimed as an I African lookalike for rosewood, bubinga unfortunately has a tendency to gum up the works.

Highly prized bubinga (Guibourtia demeusei) is a beautiful, expensive hardwood featuring medium red-tobrown wood with lighter red to purple veining. The grain may be straight or interlocked. And its striking appearance is so similar to rosewood, it is often calledmisleadingly soAfrican rosewood.

But bubinga is available only in limited supply to the U.S., perhaps in part due to the sticky problems it presents. In seasoning, the wood dries easily but occasionally experiences gum exudation. Slow seasoning will avoid distortion and checking.

In addition, the timber works easily enough on both hand and machine tools, although the gum pockets may cause problems. The gum pockets are also a source of trouble in steam bending and gluing bubinga.

The fancier, interlocked and irregular grained pieces also tend to tear or pick up, requiring a l5' cut- ting angle for planing or moulding. The wood may cause extreme blunting of cutting edges, which then must constantly be maintained. Nailing of bubinga requires pre-boring.

Story at a Glance

African bubinga resembles rosewood in appearance and price. gum exudationcauses problems in drying, working, steam bending and gluing used for decorative veneers.

That the hardwood is a very hard and heavy wood, though, really does not present problems in machining. Its average weight is 57 lbs. per cu. ft. and its specific gravity averages 0.88. Bubinga logs may be hugel some imported to the U.S. have tipped the scales at up to l0 tons. Trees grow 130 to 150 ft. tall, with straight cylindrical boles up to 70 ft. and average trunk diameters of 3 to 5 ft.

The heartwood is resistant to preservative treatment and termite at- tack, but only somewhat resistant to marine borers, Yet it is susceptible to attack by the common furniture beetle. Its whitish sapwood is permeable.

Bubinga is primarily peeled for decorative veneers, the decorative rotary cut wood known as kevazingo. The slicing olten showcases its natural wild, swirling, veined appearance, while the wood stains easily and can be brought to an excellent finish.

It is also a superb wood for turnery producing [urniture construction pieces such as bedposts and chair rails and parts; for inlay work in objects such as tables with checkerboards, and for fancy items, including knife handles and brush backs.

Besides African rosewood, other names for this member of the Leguminosae family include essingang in Cameroon and buvenga in Gabon. The hardwood is found chiefly in equatorial African areas such as Cameroon and Gabon, also reaching into Zaire and the Congo region. The trees thrive in damp areas, being abundant in swamps, wetland forests and near rivers and lakes.