Keruing or apitong (Dipterocarpus) is widely scattered throughout the Indo-Malaysian region. Most of the more than 70 species in this genus are marketed under the name keruing. Other important species are marketed as apitong in the Philippine Islands and yang in Thailand.
The heartwood varies from light to dark red-brown or brown to dark brown, sometimes with a purple tint; the heartwood is usually well defined from the gray or buff-colored sapwood. Similar to kapur (Dryobalanops), the texture of keruing is moderately coarse and the grain is straight or shallowly interlocked. The wood is strong, hard, and heavy (density of air-dried wood is 720 to 800 kg/m3 (45 to 50 lb/ft3)); this wood is characterized by the presence of resin ducts, which occur singly or in short arcs as seen on endgrain surfaces. This resinous condition and the presence of silica can present troublesome problems. Sapwood and heartwood are moderately resistant to preservative treatments. However, the wood should be treated with preservatives when it is used in contact with the ground. Durability varies with species, but the wood is generally classified as moderately durable. Keruing generally takes to sawing and machining, particularly when green, but saws and cutters dull easily as a result of high silica content in the wood. Resin adheres to machinery and tools and may be troublesome. Also, resin may cause gluing and finishing difficulties.
Keruing is used for general construction work, framework for boats, flooring, pallets, chemical processing equipment, veneer and plywood, railroad crossties (if treated), truck floors, and boardwalks.
*Much of the base wood information presented here is made available by the USDA FPL FS. If you are interested in a much more technical description of wood properties, I encourage you to visit the source.