Working with Billian in Custom Epoxy River Builds
Billian (Eusideroxylon zwageri), an exceptionally dense hardwood from Asia-Oceania belonging to the Lauraceae family, is widely celebrated for its structural strength and legendary weathering resistance. While traditionally utilized in marine pilings and heavy industrial construction, builders crafting distinctive, ultra-durable epoxy river tables occasionally encounter Billian boards and slabs. Because this timber exhibits exceptional density and distinct behavioral traits during drying and fabrication, successful integration with epoxy resin requires an understanding of its material properties.
According to the CIRAD Tropix technical sheet on Billian, this timber brings formidable physical metrics to the workshop. Below are the key engineering values and shop practicalities you need to plan your tabletop build.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Eusideroxylon zwageri | |
| Colour / texture / grain | Yellow brown; texture fine; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.93 | about 58.1 lb/ft³; a 2-inch-thick slab weighs about 9.7 lb per sq ft |
| Total tangential shrinkage | 7.5 % | green to oven-dry |
| Total radial shrinkage | 4.3 % | green to oven-dry |
| Ratio St/Sr | 1.7 | closer to 1 = less cupping tendency |
| Thermal conductivity | 0.30 W/(m·K) | |
| Crushing strength (12% MC) | 86 MPa | about 12,470 psi |
| Static bending strength (12% MC) | 143 MPa | about 20,740 psi |
| Modulus of elasticity (12% MC) | 22,690 MPa | about 3,291,000 psi |
| Decay (fungi) resistance | Durability class 1 – very durable | |
| Termite resistance | Class D – durable | |
| Dry-wood borer resistance | Class D – durable (heartw. durable but sapw. not | |
| 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: high risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 45–65 °C | about 113–149 °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).
What does Billian wood look like, and how does it present in a tabletop?
Billian heartwood displays a warm yellow-brown to reddish yellow-brown color that deepens over time, often revealing a subtle greenish tinge and a slight natural lustre. Its sapwood is pale yellowish, clearly demarcated from the heartwood, and measures between 4 to 9 cm thick on logs that typically range from 60 to 100 cm in diameter. The texture is fine, and the grain is straight or slightly interlocked. Notably, fresh quarter-sawn surfaces emit a recognizable lemon scent.
How heavy is Billian, and how does its density affect table design?
Billian is an unusually heavy wood. At 12% moisture content, its specific gravity averages 0.93, corresponding to a density of approximately 58.1 lb/ft³. A standard 2-inch-thick slab weighs roughly 9.7 lb per square foot before adding resin. This mass gives tabletops tremendous substance, but it demands sturdy leg assemblies, robust joinery, and reliable mechanical anchors. In mechanical strength, Billian tests at 86 MPa (about 12,470 psi) in crushing strength, 143 MPa (about 20,740 psi) in static bending strength, and 22,690 MPa (about 3,291,000 psi) in modulus of elasticity.
How hard is Billian wood, and how is its hardness measured?
In standard European and French timber testing, wood hardness is measured using the Monnin hardness test—a standardized scale where a higher numerical value indicates a harder, more dent-resistant surface. (Monnin hardness values cannot be converted directly into the North American Janka scale, as the test methods and calculations differ.) While the CIRAD Tropix data sheet does not publish a specific Monnin numerical index for Billian, it notes that the species possesses high hardness along with silica content, making it tough enough to serve as a direct substitute for heavy-duty timbers like Greenheart and Azobe.
What are the shrinkage rates, and what do they mean next to an epoxy river?
Total tangential shrinkage (St) from green to oven-dry is 7.5%, while total radial shrinkage (Sr) is 4.3%. This produces an St/Sr ratio of 1.7. In the context of an epoxy river table, a ratio of 1.7 indicates a moderate tendency toward distortion or cupping as environmental humidity shifts. Because cast epoxy resin is dimensionally rigid once cured, any substantial movement across the wood’s tangential face can introduce shear strain along the wood-epoxy bond line. Using quartersawn boards or ensuring slabs are dried thoroughly to local interior equilibrium moisture levels before casting will minimize stress against the epoxy core.
What are the primary drying risks when preparing Billian slabs?
CIRAD classifies the drying rate of Billian as slow. While there is only a slight risk of distortion and no known specific risk of casehardening or collapse, there is a high risk of checking. Surface and end checking can easily develop if the moisture gradient between the slab interior and surface becomes too steep. When kiln drying, suggested drying schedules operate between 45 °C and 65 °C (about 113 °F to 149 °F) with high relative humidity phases initially to avoid thermal and moisture shock that could split the wood.
How difficult is Billian to machine, saw, and fasten?
Due to its high density and silica content, Billian exerts a fairly high blunting effect on shop tooling. CIRAD advises the use of stellite-tipped saw teeth for breakdown and tungsten carbide cutting tools for milling and shaping. If you are attaching table aprons, stiffening C-channels, or mounting bases, pre-boring pilot holes is strictly necessary to prevent snapping fasteners or cracking the timber.
How does Billian bond with adhesives and resin?
The CIRAD sheet highlights that because of Billian’s high specific gravity, gluing must be performed in strict compliance with the code of practice and instructions supplied by the adhesive manufacturer. Dense, fine-textured woods with low porosity offer fewer microscopic anchors for glues, making thorough mechanical surface prep and dust removal essential before pouring an epoxy seal coat or river channel.
Is Billian naturally durable, and is it restricted by CITES?
Billian is extraordinarily durable against environmental decay. CIRAD rates the heartwood as Durability Class 1 (very durable) against wood-decaying fungi, Class D (durable) against dry-wood borers, and Class D (durable) against termites. It is Class 4 (not permeable) for heartwood treatability, and its natural durability qualifies it for Use Class 4 (in ground or fresh water contact) as well as Use Class 5 (permanent marine saltwater exposure). Furthermore, Billian is not listed in the CITES Appendices (Washington Convention 2025), meaning international trade is not governed by CITES restrictions.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because CIRAD documents that Billian requires strong steaming before decorative slicing into veneer, table builders working with thicker solid slabs should remember that the internal stresses of this dense Lauraceae species are remarkably stubborn, making gradual acclimatization in the workshop critical before final flattening. (Source: CIRAD Tropix 7 technical sheet: Billian.)