Building Wood and Epoxy Tables with Merbau
Merbau encompasses timber from species such as Intsia bijuga and Intsia palembanica (alongside botanical synonyms including Afzelia bijuga, Intsia amboinensis, Intsia retusa, and Intsia backeri). Documented extensively in the CIRAD Tropix technical sheet, this heavy hardwood offers unique visual traits and exceptional physical strength for custom river tables and furniture components.
What does Merbau look like in a finished tabletop?
Merbau heartwood displays an orangey brown tone that darkens with light exposure to a dark red brown or dark brown. A distinctive visual marker is the presence of yellow sulphur deposits within the wood structure. The sapwood is clearly demarcated from the heartwood, presenting a distinct band measuring between 5 to 8 cm thick. The grain runs straight or slightly interlocked, and the wood possesses a coarse texture that provides prominent natural character when paired alongside clear or tinted epoxy pours.
How heavy and hard is Merbau?
According to CIRAD Tropix data, Merbau carries an average specific gravity of 0.83 at 12% moisture content, which translates to a density of about 51.8 lb/ft³. For table builders, a standard 2-inch-thick slab weighs approximately 8.6 lb per square foot, requiring solid, well-engineered table bases.
Its hardness is rated at 8.8 on the Monnin hardness scale. The Monnin scale is an established French measurement where higher numerical values represent harder woods (distinct from indentation scales like Janka). An 8.8 rating denotes a dense, hard surface with great crush resistance (crushing strength of 74 MPa or about 10,730 psi), making it highly resistant to daily tabletop wear.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Intsia bijuga, Afzelia bijuga (synonymous), Intsia amboinensis (synonymous), Intsia retusa (synonymous), Intsia palembanica, Intsia backeri (synonymous), Intsia p.p. | |
| Colour / texture / grain | Brown; texture coarse; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.83 | about 51.8 lb/ft³; a 2-inch-thick slab weighs about 8.6 lb per sq ft |
| Monnin hardness (12% MC) | 8.8 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 4.4 % | green to oven-dry |
| Total radial shrinkage | 2.7 % | green to oven-dry |
| Ratio St/Sr | 1.6 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.39 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 24 % | |
| Thermal conductivity | 0.27 W/(m·K) | |
| Crushing strength (12% MC) | 74 MPa | about 10,730 psi |
| Static bending strength (12% MC) | 115 MPa | about 16,680 psi |
| Modulus of elasticity (12% MC) | 15,440 MPa | about 2,239,000 psi |
| Decay (fungi) resistance | Durability class 1-2 – very durable to durable | |
| Termite resistance | Class M – moderately durable | |
| Dry-wood borer resistance | Class D – durable (sapwood demarcated, risk limited | |
| Heartwood treatability | Class 4 – not permeable | |
| Use class from natural durability | Class 4 – in ground or fresh water contact | |
| Drying | rate slow; distortion: slight risk; checking: slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 48–60 °C | about 118–140 °F |
| Machining | blunting fairly 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). |
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).
How stable is Merbau next to an epoxy resin river?
CIRAD Tropix classifies Merbau as a stable wood. It exhibits low shrinkage properties from green to oven-dry:
- Total tangential shrinkage (St): 4.4%
- Total radial shrinkage (Sr): 2.7%
- Shrinkage ratio (St/Sr): 1.6
- Fibre saturation point: 24%
- Coefficient of volumetric shrinkage: 0.39% per % MC
Because its shrinkage ratio is a modest 1.6 and overall dimensional movement is limited, Merbau stays exceptionally flat. This low movement reduces stress along the epoxy-to-wood bond lines during indoor seasonal humidity shifts.
What drying behaviors and risks should builders expect?
Merbau has a slow drying rate. The technical data notes only a slight risk of distortion and a slight risk of surface checking, with no known specific risks for collapse or casehardening. However, CIRAD notes that care is required to avoid surface cracks when drying thick boards. Suggested kiln schedules operate between 48 °C and 60 °C (approximately 118 °F to 140 °F) to gently bring the lumber down to target moisture levels without degrading the wood.
What should you anticipate when cutting and machining Merbau?
Working Merbau demands dedicated tooling consideration. The CIRAD Tropix sheet notes that the blunting effect on tools is fairly high due to variable silica content. Recommended tooling includes stellite-tipped sawteeth and tungsten carbide cutting edges. Builders should also take note of two operational quirks:
- Sawblades tend to clog during cutting operations.
- There is an observed tendency toward tearing on quartersawn surfaces.
What are the key gluing, fastening, and finishing considerations?
Merbau has good holding for mechanical fasteners, but pre-boring is strictly necessary because the wood tends to split when nailed or screwed. Due to its high specific gravity, adhesive bonding must be performed carefully in compliance with standard shop trade practice and the specific resin manufacturer instructions.
A critical consideration for builders is extractive bleed: the technical sheet warns of a risk of dripping due to tannin-type colored chemical compounds in the wood. These water-soluble compounds can cause aesthetic damage to nearby structures if exposed to moisture, making thorough sealing of the slab essential before and after epoxy casting.
What is Merbau’s durability and CITES status?
Merbau displays outstanding natural resistance. The heartwood is listed in Durability class 1-2 (very durable to durable) against xylophagous fungi, Class D against dry wood borers, and Class M (moderately durable) against termites. It is classified as Class 4 (not permeable) for heartwood treatability and qualifies for use class 4 (in ground or fresh water contact). Common end-uses include cabinetwork, high-class furniture, flooring, heavy carpentry, and musical instruments. Regarding international trade restrictions, this species is not listed in the CITES Appendices (Washington Convention 2025).
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: When designing wide table layouts from large Merbau logs (which range from 60 to 120 cm in diameter), keep in mind that while the heartwood resists dry-wood borers (Class D), CIRAD notes that borer risk remains limited to the 5 to 8 cm sapwood perimeter, so check any live edges thoroughly before embedding them in resin. (Source: CIRAD Tropix 7 technical sheet: Merbau.)