Working with Kempas in Epoxy River Tables
Kempas (Koompassia malaccensis) is an imported hardwood harvested from lowland and swamp forests in Malaysia and Indonesia. In custom river tables and bespoke furniture, the wood provides a distinctive appearance. Freshly cut heartwood displays a brick-red tone that naturally deepens upon air exposure into an orange-red or rich red-brown hue, accented by contrasting yellow-brown streaks from soft axial parenchyma tissue around the pores. Its coarse texture and interlocked grain give slabs bold visual depth alongside deep-pour resin castings.
Density and Physical Durability
Kempas is classified as a hard, heavy timber. In furniture applications, harder woods resist dents, scratches, and daily impacts far better than softer hardwoods, making Kempas well-suited for high-traffic dining tables, desks, and boardroom conference tops. However, because of its high density and interlocked grain structure, Kempas is difficult to work with hand and machine tools. Planers and jointers must be kept sharp, and feed rates should remain steady to prevent tearout along the reversing grain before framing the slab inside an epoxy mold form.
Key Wood Properties
| Property Metric | Value (USDA FPL-GTR-282) |
|---|---|
| Radial Shrinkage (Green to Ovendry) | 6.0% |
| Tangential Shrinkage (Green to Ovendry) | 7.4% |
| Volumetric Shrinkage (Green to Ovendry) | 14.5% |
| Air-Dried Density | 880 kg m–3 (55 lb ft–3) |
Tangential vs. Radial Movement in Slab Design
Wood naturally expands and contracts across its cell structure in response to shifting humidity, whereas cured epoxy resin remains dimensionally stable. For an epoxy river table, managing this differential movement is essential to prevent internal stress, joint separation, or edge fractures along the resin bondline.
Total shrinkage from green to ovendry conditions measures 6.0% in the radial dimension and 7.4% in the tangential dimension, with total volumetric shrinkage at 14.5%. Because tangential movement exceeds radial movement, flatsawn boards will shift more across their face width than quartersawn sections. Fortunately, the ratio between tangential and radial shrinkage in Kempas is relatively balanced compared to many other tropical species. This close relationship helps the timber dry predictably, though the material still carries an inherent tendency to warp and check if moisture shifts rapidly.
Epoxy Sealing and Table Construction Tips
- Dry to Stable Moisture Content: Slabs must be seasoned to a stable moisture equilibrium prior to casting. Uneven drying invites checking and warp that can break the chemical bond with cured epoxy.
- Apply a Thorough Seal Coat: The coarse texture and open pore structure of Kempas can harbor trapped air. Applying a preliminary seal coat of clear epoxy over all surfaces and live edges seals the axial parenchyma channels, preventing outgassing bubbles from rising into subsequent deep pours.
- Account for Seasonal Movement: When mounting cured tabletops to metal or wooden bases, always use slotted screw holes or expansion fasteners rather than fixed joints. Allowing the timber to expand and contract across its width prevents internal stress fractures against the rigid epoxy channel.
Sources
USDA Wood Handbook (FPL-GTR-282)
Published October 28, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: If you are building outdoor or high-moisture installations, note that while Kempas heartwood resists decay fungi, it remains vulnerable to termite activity unless treated, though it accepts preservative retention as high as 320 kg m–3 (20 lb ft–3) per the USDA Wood Handbook (FPL-GTR-282).