Comparative Hardness and Density
The Janka hardness scale ranks wood species based on the force it takes to press a specifically sized ball-bearing halfway into its surface. Based on this test, yellow balau has a rating of 1,600 pounds-per-foot-squared, which means it is harder than most domestic hardwoods and about a third as hard as Brazilian walnut, one of the hardest exotic species. With a specific gravity of around 0.70, it easily floats on water, and its density is 53 pounds-per-foot-cubed, which makes it more dense than common domestic species such as white oak, maple and hickory.
Yellow balau has a coarse texture, and the grain has large pores with few knots, although it is sometimes interlocked with occasional resin pockets. The tree is susceptible to infestations of the Pinhole Borer Beetle that leaves tiny holes in the grain -- these holes have no effect on the strength or workability of the timber. The color of the sapwood ranges from yellowish-brown to tan, while the heartwood is a darker brown. Like most timbers, yellow balau turns a silvery-gray when exposed to sunlight for an extended period. Yellow balau has little natural resistance to rot and insects.
Working With Yellow Balau
Because of its density and grain structure, yellow balau tends to be difficult to work. Nailing it is difficult, partly because it resists nails and partly because it splits when nails do penetrate the grain. Consequently, you must predrill holes for nails and screws. Stainless-steel fasteners are recommended, because the wood reacts with ones containing iron to produce black stains. Moreover, some varieties contain silica which have a dulling effect on saw blades and shaping tools. Another consequence of the wood's density is that fresh lumber takes a long time to dry, and shrinkage is common if the wood is used before it has dried.
Uses for Yellow Balau
Because of its hardness and density, yellow balau is primarily a utility-grade wood for exterior projects. Common uses include decks and planking for ships, sleepers for bridges and railways, docks and wharves, pallets and veneer for utility-grade plywood -- sometimes called lauan plywood. It accepts finishes well and has an attractive grain and color, so yellow balau is also a common material for flooring and decking. Because of the tendency of the wood to shrink as it dries out, it isn't an appropriate material for cabinetry or indoor woodworking projects, although it is frequently used for outdoor furniture.