Working with Jelutong in Wood and Epoxy Builds
Jelutong refers to commercial timber from the genus Dyera, primarily Dyera costulata and Dyera polyphylla, originating from Asia-Oceania in countries such as Indonesia and Malaysia. According to the CIRAD Tropix technical sheet for Jelutong, mature logs reach diameters from 80 to 120 cm. The species is not listed in the CITES Appendices (Washington Convention 2025). In woodworking, Jelutong is historically valued for sculpture, patternmaking, mouldings, interior joinery, and furniture components, often serving as an alternative to obeche or poplar. For epoxy river table builders, its uniform cream-white to light yellow tone, straight grain, and mild shrinkage profile present distinct advantages, balanced by mechanical softness and unique anatomical characteristics.
Appearance, Density, and Hardness
The heartwood of Jelutong is light yellow or cream white, and the sapwood is not demarcated from the heartwood. It possesses a fine texture, straight grain, and completely absent interlocked grain. One defining anatomical feature recorded by CIRAD is the frequent presence of large latex canals, along with the presence of brittleheart in logs.
Jelutong is a relatively lightweight hardwood. At 12% moisture content, it has an average specific gravity of 0.45, translating to a density of approximately 28.1 lb/ft³. A 2-inch-thick slab weighs roughly 4.7 lb per square foot. On the Monnin hardness scale—a French testing standard where higher values represent harder timber—Jelutong measures 1.6. Because this is Monnin hardness rather than a Janka rating, builders should evaluate it within the context of lightweight, easily worked interior woods rather than dense architectural hardwoods. Its crushing strength is 27 MPa (about 3,920 psi), static bending strength is 45 MPa (about 6,530 psi), and modulus of elasticity is 10,040 MPa (about 1,456,000 psi).
Dimensional Movement Next to Epoxy
In custom river tables, wood movement against rigid cured epoxy resin is a primary engineering concern. Jelutong exhibits moderate to low overall shrinkage. CIRAD records total tangential shrinkage at 5.5% and total radial shrinkage at 2.3%, yielding an St/Sr ratio of 2.4. Its coefficient of volumetric shrinkage is 0.35% per percent change in moisture content. Because the absolute shrinkage percentages are modest, properly dried Jelutong imparts relatively low seasonal stress along epoxy bond lines, though its 2.4 ratio indicates that tangential grain moves more than twice as much as radial grain.
Pros and Cons for River Table Builders
Pros
- Mild Distortion Risk: CIRAD reports no risk or very slight risk of distortion during drying.
- Consistent Texture: Fine texture and straight grain with absent interlocked grain allow clean, predictable surfacing.
- Lightweight Handling: At about 28.1 lb/ft³ at 12% moisture content, large wide tabletops remain easy to transport and mount.
- Permeable Structure: Classified as Class 1 (easily permeable), accepting deep penetration of low-viscosity seal coats.
- Standard Tooling: Blunting effect is normal; ordinary or alloy steel tools cut the wood cleanly without specialized carbide tooling.
Cons
- Latex Canals: Large latex canals create surface voids and run a risk of developing localized surface checks.
- Non-Durable Heartwood: Durability class 5 (not durable against fungi) and Class S (susceptible to dry-wood borers and termites), restricting use strictly to dry interior environments (Class 1 – inside, no dampness).
- Latex Residue: Natural latex in the timber can clog sawteeth during processing.
- Low Mechanical Resistance: A Monnin hardness of 1.6 and poor screw-holding capacity require careful consideration when securing heavy structural table bases.
- Stain Vulnerability: CIRAD notes explicit risks of blue stain during processing.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Dyera costulata, Dyera polyphylla, Dyera p.p. | |
| Colour / texture / grain | Light yellow; texture fine; grain straight; interlocked grain absent | |
| Specific gravity (12% MC) | 0.45 | about 28.1 lb/ft³; a 2-inch-thick slab weighs about 4.7 lb per sq ft |
| Monnin hardness (12% MC) | 1.6 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.5 % | green to oven-dry |
| Total radial shrinkage | 2.3 % | green to oven-dry |
| Ratio St/Sr | 2.4 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.35 % per % MC | volume change per 1% change in moisture content |
| Thermal conductivity | 0.16 W/(m·K) | |
| Crushing strength (12% MC) | 27 MPa | about 3,920 psi |
| Static bending strength (12% MC) | 45 MPa | about 6,530 psi |
| Modulus of elasticity (12% MC) | 10,040 MPa | about 1,456,000 psi |
| Decay (fungi) resistance | Durability class 5 – not durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class S – susceptible (risk in all the wood) | |
| Heartwood treatability | Class 1 – easily permeable | |
| Use class from natural durability | Class 1 – inside (no dampness) | |
| Drying | rate rapid; distortion: no risk or very slight risk; checking: slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–62 °C | about 127–144 °F |
| Machining | blunting normal; saw teeth: ordinary or alloy steel; cutting tools: ordinary | |
| Nailing and screwing | Poor | |
| CITES status | This species is not listed in the CITES Appendices (Washington Convention 2025). |
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).
Build Notes for the Epoxy Shop
Slab Selection
Look for solid boards free of brittleheart, a common defect documented in Jelutong logs. Inspect both faces for large latex canals, which appear as slit-like openings across the grain. Because sapwood is not demarcated, color across the slab is very uniform, creating a pale, clean backdrop that pairs well with colored or deep translucent epoxy resins.
Drying
Jelutong features a rapid drying rate with no known risk of collapse or casehardening. However, CIRAD warns of pocket moisture in thick stock, slight checking risk, surface checking caused by latex canals, and susceptibility to blue stain. For kiln drying, suggested program temperatures range from 53 °C to 62 °C (about 127 °F to 144 °F). Ensure thick slabs are thoroughly equalized throughout their core before pouring resin.
Machining
Jelutong machines easily using ordinary cutting tools. However, the wood’s latex content can build up and clog sawteeth. Keep cutter heads clean and maintain razor-sharp cutting edges to produce a smooth, tearout-free surface. Because nailing and screwing resistance is rated poor, table bases should be fastened using threaded inserts with generous thread depth rather than direct wood screws.
Sealing and Finishing
Due to Jelutong’s Class 1 permeability, a dedicated epoxy seal coat should be applied before the main river pour. Pre-sealing prevents air bubbles from releasing out of the wood pores and seals open latex canals. With a Class 1 interior use rating and durability class 5 rating against wood-rotting fungi, completed tables must remain strictly indoors in dry settings. Apply a uniform finish across all faces and edges to control ambient moisture exchange.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because CIRAD highlights pocket moisture in thick material alongside rapid surface drying, verify moisture readings across the center of thick Jelutong slabs with a deep-probe meter to avoid trapped wet pockets beneath an epoxy river. (Source: CIRAD Tropix 7 technical sheet: Jelutong.)