Keruing (Dipterocarpus spp.) in Custom Epoxy River Table Builds
Keruing represents timber from several species of the genus Dipterocarpus (including Dipterocarpus acutangulus, Dipterocarpus grandiflorus, and Dipterocarpus alatus, also known under the trade name Yang). Sourced from Asia-Oceania, these large trees produce logs ranging from 70 to 120 cm in diameter with a clearly demarcated sapwood band between 5 and 7 cm thick. When considering Keruing for custom epoxy river tables, furniture builders must balance its dense, strong structure against high shrinkage rates, blunting tool wear, and natural resin exudations. Below are technical answers based on data from the CIRAD Tropix technical sheet for mature Keruing lumber.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Dipterocarpus acutangulus, Dipterocarpus alatus, Dipterocarpus appendiculatus, Dipterocarpus baudii, Dipterocarpus borneensis, Dipterocarpus caudatus, Dipterocarpus costulatus, Dipterocarpus gracilis, Dipterocarpus pilosus (synonymous), Dipterocarpus grandiflorus, Dipterocarpus kerrii, Dipterocarpus verrucosus, Dipterocarpus p.p. | |
| Other trade names | Yang | |
| Colour / texture / grain | Red brown; texture coarse; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.79 | about 49.3 lb/ft³; a 2-inch-thick slab weighs about 8.2 lb per sq ft |
| Monnin hardness (12% MC) | 4.6 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 10.0 % | green to oven-dry |
| Total radial shrinkage | 5.4 % | green to oven-dry |
| Ratio St/Sr | 1.9 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.54 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 34 % | |
| Thermal conductivity | 0.26 W/(m·K) | |
| Crushing strength (12% MC) | 65 MPa | about 9,430 psi |
| Static bending strength (12% MC) | 115 MPa | about 16,680 psi |
| Modulus of elasticity (12% MC) | 16,610 MPa | about 2,409,000 psi |
| Decay (fungi) resistance | Durability class 3 – moderately durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class D – durable (sapwood demarcated, risk limited | |
| Heartwood treatability | Class 3 – poorly permeable | |
| Use class from natural durability | Class 3.1 according to NF P 23-305 standard (December 2014). Class 3.2 may be considered with preservation | |
| Drying | rate slow; distortion: high risk; checking: high risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 48–60 °C | about 118–140 °F |
| Machining | blunting high; saw teeth: stellite-tipped; cutting tools: tungsten carbide | |
| Nailing and screwing | Good but pre-boring necessary | |
| CITES status | This species is not listed in the CITES Appendices (Washington Convention 2025). Quarter sawn Description of logs Diameter. From 70 to 120 cm Thickness of sapwood. From 5 to 7 cm Floats. No Log durability. Moderate (treatment recommended) |
Values from the CIRAD Tropix technical sheet (average values for mature wood, 12% moisture content where noted). US-unit conversions are calculated by BigEpoxy (1 MPa = 145.04 psi; density = specific gravity × 62.43 lb/ft³).
What does Keruing look like, and how does its grain present in tabletops?
Keruing heartwood displays a range from light red to red brown or purplish red brown. The sapwood is clearly demarcated, creating high visual contrast if edges are retained. The grain runs straight or slightly interlocked, accompanied by a coarse texture. CIRAD Tropix documentation notes the presence of resin and possible wind shakes (internal fractures within the wood). When planning a tabletop layout, builders should inspect boards carefully for these internal fractures. Additionally, quartersawn material can show occasional tearing during surfacing.
How heavy and hard is Keruing wood?
Keruing is a heavy, dense hardwood with a specific gravity of 0.79 at 12% moisture content. In practical shop terms, this corresponds to approximately 49.3 lb/ft³, meaning a 2-inch-thick tabletop slab weighs about 8.2 lb per square foot. Mechanical testing shows high structural strength, with a crushing strength of 65 MPa (around 9,430 psi), a static bending strength of 115 MPa (about 16,680 psi), and a modulus of elasticity of 16,610 MPa (around 2,409,000 psi).
Its hardness is measured at 4.6 on the Monnin hardness scale at 12% moisture content. The Monnin scale is a French standardized test where higher numbers reflect harder wood; it is not a Janka measurement and should never be converted into one. A Monnin value of 4.6 signifies a firm surface that resists denting in heavy tabletop use.
How does Keruing move, and what does its shrinkage mean next to an epoxy river?
Dimensional movement is a critical factor when pairing wood with rigid epoxy resin. Keruing exhibits substantial movement from green to oven-dry:
- Total tangential shrinkage: 10.0%
- Total radial shrinkage: 5.4%
- Tangential to radial ratio (St/Sr): 1.9
- Coefficient of volumetric shrinkage: 0.54% per % moisture content
- Fibre saturation point: 34%
The tangential shrinkage of 10.0% and volumetric coefficient of 0.54% per percentage of moisture content place Keruing in a category with high overall movement. The St/Sr ratio of 1.9 indicates moderate cupping tendencies if tangential boards encounter moisture swings. When locked next to an epoxy river, any substantial change in ambient humidity can exert stress along the epoxy-wood bondline. Slabs must be thoroughly dried and acclimated to interior equilibrium before casting.
What drying risks and moisture variations affect Keruing?
Drying Keruing requires caution. The CIRAD Tropix guide rates the drying rate as slow, noting a high risk of distortion and a high risk of checking (though collapse and casehardening present no known specific risks). Moisture content is known to be very variable, especially among the most resinous species in the group. Recommended kiln schedules suggest operating temperatures between 48 °C and 60 °C (about 118 °F to 140 °F). To mitigate checking and warping during drying, careful stacking and end coating are recommended.
How does Keruing handle machining and tooling?
Keruing exerts a high blunting effect on cutter edges. The wood contains variable silica content, and several species in the Dipterocarpus group are heavily resinous, which can clog saw blades, router bits, and planer knives. CIRAD recommends using stellite-tipped saw teeth and tungsten carbide cutting tools. Pre-boring is strictly necessary for all nailing and screwing operations despite good overall mechanical holding.
What should builders know about gluing, resin exudation, and finishes?
The CIRAD Tropix sheet specifically warns that resin exudations must be taken into account when gluing. Because active resin channels can bleed extractives to the surface, standard adhesive joints and epoxy pours can suffer bond interference if wood surfaces are not cleaned immediately prior to assembly. Fabricators working with Keruing should remove surface resin bleeds and ensure bare edges are freshly prepared before pouring resin or applying adhesives.
What is Keruing’s natural durability and CITES protection status?
Keruing heartwood is rated as Durability Class 3 (moderately durable) against wood-decay fungi. It is rated Class D (durable) against dry wood borers, with attack risk limited to the sapwood. However, it is classified as Class S (susceptible) to termites, and heartwood treatability is Class 3 (poorly permeable). In the European standard NF EN 350, Keruing covers use class 3.1 without preservation treatment. Keruing is not listed in the CITES Appendices (Washington Convention 2025). Outside of decorative joinery, its recorded commercial end-uses include interior and exterior joinery, flooring, indoor staircases, ship planking and decking, heavy carpentry, vehicle flooring, and plywood veneer.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because Keruing heartwood is poorly permeable (treatability Class 3) and termites find it susceptible (Class S), table bases or slabs intended for covered patio or semi-exterior use should rely on sound drainage detailing rather than expecting deep preservative penetration. (Source: CIRAD Tropix 7 technical sheet: Keruing.)