Gurjan / Keruing Wood (Dipterocarpus): Properties & Uses

What Gurjan / Keruing Is

Gurjan and keruing are not a single wood but two trade names for the same group of timbers from the genus Dipterocarpus, which contains roughly 70 species 14. "Gurjan" (also spelt gurjun or garjan) is the name used in India, Bangladesh and Myanmar, while "keruing" is the standard international trade name for the mixed genus timber, and the same wood turns up as apitong in the Philippines, yang in Thailand and dau in Vietnam 2. The Indian gurjan of commerce is drawn chiefly from Dipterocarpus turbinatus, with several related species contributing to the trade. Because the trade name covers so many species, no two parcels are identical, and density and strength can shift noticeably from one shipment to the next.

Where It Grows

The genus is spread across South and Southeast Asia, from north-eastern India and the Andaman and Nicobar Islands through Bangladesh, Myanmar, Thailand, Cambodia, Laos and Vietnam, and on into Peninsular Malaysia, Borneo, Sumatra and the Philippines 25. Dipterocarpus is one of the dominant components of the region's lowland and hill tropical rainforest, where the trees grow as large emergents standing above the surrounding canopy 6. They reach 30–45 m and occasionally up to 60 m, with straight cylindrical boles of 1–1.5 m diameter that are often buttressed and clear of branches for much of their height, which is what makes the genus so productive as a source of large plywood veneer.

Appearance and Grain

The heartwood ranges from pinkish and red-brown to grey-brown and darkens as it is exposed to light, and it is not sharply set off from the paler grey-brown sapwood 1. The grain is straight to shallowly interlocked and the texture is moderately coarse but fairly even. The most distinctive feature of the wood is its resin: Dipterocarpus timbers carry a natural oleoresin (the source of gurjun oil) that gives freshly worked stock a clear resinous smell and can leave the surface sticky 2. In panel form the face reads as a warm, even brown once dressed, which is why it is accepted as a structural face veneer as well as a core.

Weight, Density and Strength

Keruing is a genuinely heavy hardwood. The Wood Database puts the genus average at about 745 kg/m³ (46 lb/ft³) at 12% moisture, while PROSEA reports a broad species range of 600–980 kg/m³, so parcels run from moderately heavy to heavy 13. In round terms that is several hundred kg/m³ heavier than our lightweight partner species, okoume — see our okoume entry for its own weight and strength figures. Janka side hardness averages around 1,390 lbf (6,170 N), within a genus spread of about 800–1,640 lbf (3,575–7,300 N) 13. Bending strength (modulus of rupture) is around 115 MPa and stiffness (elastic modulus) around 15.8 GPa on typical figures, again with wide species ranges behind those averages 13. This combination of density, hardness and stiffness is exactly why keruing is the structural counterpart to lighter tropical veneers.

Working, Gluing and Finishing

Keruing peels well into veneer, which is the foundation of its place in the plywood trade, and it works reasonably with hand and machine tools. The catch is that it carries silica, which blunts cutting edges quickly, so tungsten-carbide tooling is preferred 1. The high resin content can gum up saw blades and interfere with gluing, staining and finishing, and it may bleed to the surface if the stock is not properly seasoned. The wood also shrinks a great deal and can distort, so it must be dried carefully and slowly. In well-made plywood these issues are managed through correct drying and adhesive selection, and finished panels bond and dress reliably; it is the raw timber, not the finished panel, that needs the care.

Durability and Treatment

Keruing is rated moderately durable. The heartwood resists decay to a moderate degree but is vulnerable to termites and other insects, and the sapwood is prone to powder-post beetle and pinhole borer attack 1. It also takes preservative treatment poorly, so it is best kept out of prolonged ground or weather contact unless it has been treated. High shrinkage and only moderate dimensional stability mean movement in service is rated large, reinforcing the need for careful seasoning. For plywood used under cover or protected within a structure — the great majority of packing and construction applications — these limits are readily managed.

Sustainability and Legality

The genus is not listed on CITES, but responsible sourcing still matters. The principal Indian gurjan species, D. turbinatus, is assessed as Vulnerable on the IUCN Red List, driven by logging pressure and habitat loss 25. Because the trade name pools many species with differing Red List assessments, buyers cannot assume every parcel carries the same conservation profile. The practical rule is to prefer legally harvested, verified or certified supply and to keep proper chain-of-documentation, which is standard practice for tropical hardwood veneer.

How Cochin Wood Uses Gurjan / Keruing

At Cochin Wood Industries, gurjan is the strength counterpart to okoume. Where okoume gives us a light, smooth face for panels chosen on weight and appearance, gurjan gives us density, stiffness and load-bearing capacity. We use it as a structural face and, more importantly, as the core for container-flooring and heavy-duty plywood, where the panel has to carry point loads, resist abrasion and stay stiff under repeated stress. Its heavy density and high bending strength are precisely the properties that heavy-duty flooring demands, and its ready availability in large veneer sizes keeps it practical for volume production. If you are weighing the two woods against each other, our okoume vs gurjan guide sets out the trade-offs, our container flooring plywood page covers the heavy-duty grade in detail, and our okoume encyclopedia entry covers the lightweight partner species.