Bintangor as a Slab and Board Timber for Epoxy Tables
Bintangor covers several species within the Calophyllum genus, including Calophyllum ferrugineum, Calophyllum inophyllum, Calophyllum neo-ebudicum, Calophyllum papuanum, Calophyllum teysmannii, and Calophyllum vitiense. Sourced across Africa and Asia-Oceania from trees typically measuring 50 to 100 cm in diameter, it is recognized for traditional end-uses such as cabinetwork, high-class furniture, interior joinery, flooring, indoor staircases, and ship decking or ribs. When selected for wood-and-epoxy tabletops or live-edge river tables, Bintangor provides an attractive aesthetic, but its mechanical and drying behaviors require careful preparation in the workshop, as detailed in data from the CIRAD Tropix technical sheet.
Appearance, Figure, and Wood Density
The heartwood of Bintangor displays a dark red color, often shifting from brown-red to pinkish brown, frequently accented by darker veins. Its texture is medium, and it features an interlocked grain that is typically rated as slight. The sapwood measures 5 to 10 cm in thickness and is clearly demarcated from the darker heartwood, creating a striking contrast if you choose to preserve the sapwood on a live edge.
In terms of mass, Bintangor has an average specific gravity of 0.74 at 12% moisture content. In practical shop terms, this translates to a density of about 46.2 lb/ft³, meaning a 2-inch-thick slab weighs roughly 7.7 lb per square foot. This density gives tabletops solid heft and resistance to mechanical denting.
Hardness and Mechanical Strength
On the French Monnin hardness scale, Bintangor records an average rating of 5.7 at 12% moisture content. The Monnin system measures hardness by indentation, where higher numbers signify harder wood (this scale is distinct and must never be confused with or converted to Janka values). A rating of 5.7 indicates a moderately hard surface suitable for high-traffic tabletop use.
Its structural performance is reinforced by a crushing strength of 66 MPa (about 9,570 psi), a static bending strength of 105 MPa (about 15,230 psi), and a modulus of elasticity of 14,800 MPa (about 2,147,000 psi). These metrics make slabs sufficiently stiff to bridge wide spans without excessive flex under regular use.
Shrinkage, Stability, and Epoxy Interface Considerations
The primary engineering challenge when pairing natural lumber with rigid epoxy resin is dimensional movement. Bintangor exhibits a total tangential shrinkage of 7.7% and a total radial shrinkage of 5.8%, resulting in a tangential-to-radial shrinkage ratio (St/Sr) of 1.3. A ratio of 1.3 is relatively low (close to 1), which indicates a low tendency toward cupping or distortion across radial and tangential axes.
However, Bintangor has a coefficient of volumetric shrinkage of 0.52% per percent of moisture content, alongside a fiber saturation point of 31%. If the wood gains or loses moisture after being bonded into a rigid epoxy river, dimensional stress will develop along the bond line. Thorough moisture equilibrium before sealing and pouring is essential to maintain bond integrity.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Calophyllum ferrugineum, Calophyllum inophyllum, Calophyllum neo-ebudicum, Calophyllum papuanum, Calophyllum teysmannii, Calophyllum vitiense, Calophyllum p.p. | |
| Colour / texture / grain | Dark red; texture medium; grain interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.74 | about 46.2 lb/ft³; a 2-inch-thick slab weighs about 7.7 lb per sq ft |
| Monnin hardness (12% MC) | 5.7 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 7.7 % | green to oven-dry |
| Total radial shrinkage | 5.8 % | green to oven-dry |
| Ratio St/Sr | 1.3 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.52 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 31 % | |
| Thermal conductivity | 0.24 W/(m·K) | |
| Crushing strength (12% MC) | 66 MPa | about 9,570 psi |
| Static bending strength (12% MC) | 105 MPa | about 15,230 psi |
| Modulus of elasticity (12% MC) | 14,800 MPa | about 2,147,000 psi |
| Decay (fungi) resistance | Durability class 3 – moderately 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 2 – inside or under cover (dampness possible) | |
| Drying | rate normal to slow; distortion: high risk; checking: slight risk; collapse: yes; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–65 °C | about 127–149 °F |
| Machining | blunting normal; saw teeth: ordinary or alloy steel; cutting tools: ordinary | |
| 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).
Drying Risks, Machining, and Surface Preparation
CIRAD records Bintangor’s drying rate as normal to slow. Builders must be aware that the timber carries a high risk of distortion, a risk of collapse, and a risk of end checks, though casehardening presents no known specific risk. CIRAD drying notes recommend aligning spacer sticks directly over piles to prevent warping, andSuggested kiln temperatures run between 53 °C and 65 °C (about 127 °F to 149 °F).
When cutting and shaping, tool blunting is normal, and ordinary cutting tools or ordinary/alloy steel saw teeth perform satisfactorily. However, Bintangor harbors risks of internal stresses and a tendency to woolliness during machining, largely due to interlocked grain. Surface filling is explicitly recommended to achieve a smooth finish before applying final topcoats. In assemblies involving mechanical fasteners, pre-boring is necessary despite its good nailing holding power.
Durability and CITES Status
Bintangor heartwood is rated Durability Class 3 (moderately durable) against xylophagous fungi, Class M (moderately durable) against termites, and Class D (durable) against dry-wood borers, with borer risk confined to the sapwood. Heartwood treatability is Class 4 (not permeable). The timber corresponds to Use Class 2 (inside or under cover, where dampness is possible), making it well matched for climate-controlled indoor furniture. It is not listed in the CITES Appendices (Washington Convention 2025).
Practical Pre-Pour Checklist for Bintangor
- Verify that boards or live-edge slabs have completely equalized to interior shop humidity to minimize movement against rigid resin.
- Inspect the slab thoroughly for collapse, warping, or end checks resulting from drying stresses.
- Plane or scrape the face carefully to spot and address any woolly grain patches caused by interlocked fibers.
- Clean out loose fibers along the live edge where the clearly demarcated sapwood meets the casting area.
- Apply a pore-filling sealer to the wood surface and river edges as recommended to prevent outgassing and yield a clean finish.
- Pre-bore all screw holes on the underside where table base mounting hardware or threaded inserts will sit.
- Follow the epoxy manufacturer’s data sheet for mixing ratios, maximum pour depth, and ambient shop temperatures during the pour.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: CIRAD notes highlight that Bintangor can be utilized for high-class furniture provided the grain is not highly interlocked, so inspect individual boards closely for severe fiber twist before committing them to wide, flat tabletops. (Source: CIRAD Tropix 7 technical sheet: Bintangor.)