An Introduction to Eyoum
Eyoum represents several African hardwood species within the Dialium genus, primarily Dialium aubrevillei, Dialium bipidense, Dialium dinklagei, and Dialium pachyphyllum. Sourced from trees with trunk diameters typically ranging from 60 to 100 cm, this dense timber provides solid dimensions for slab preparation. According to the CIRAD Tropix technical sheet, the heartwood presents a rich red brown tone, varying from light pinkish brown to brown, red brown, or even very dark shades. Its sapwood spans 4 to 8 cm in thickness and is clearly demarcated from the dark heartwood, offering striking edge contrast for live-edge epoxy builds. The grain ranges from straight to entangled, featuring marked interlocked grain and a medium texture.
Weight, Hardness, and Mechanical Strength
Builders should anticipate an extremely heavy workpiece when handling Eyoum. With an average specific gravity of 0.94 at 12% moisture content, the wood weighs roughly 58.7 lb/ft³, meaning a standard 2-inch-thick slab clocks in at approximately 9.8 lb per square foot. Strong internal framework, substantial leg systems, and appropriate shop handling equipment are required when managing full-sized river tabletops built with this timber.
Eyoum also brings remarkable surface resistance. On the French Monnin hardness scale—where higher numbers indicate harder timber and values must not be confused with or converted to Janka ratings—Eyoum scores an impressive 10.3. This extreme surface hardness ensures outstanding resistance against tabletop dents and scratches. Mechanically, the mature wood provides an average crushing strength of 90 MPa (about 13,050 psi), a static bending strength (modulus of rupture) of 162 MPa (about 23,500 psi), and a modulus of elasticity of 22,700 MPa (about 3,292,000 psi).
Shrinkage and Movement Next to an Epoxy River
When pairing solid wood boards with rigid epoxy resins, dimensional stability is a primary consideration. Eyoum demonstrates substantial overall shrinkage figures:
- Total tangential shrinkage: 8.7%
- Total radial shrinkage: 4.9%
- Tangential to radial ratio (St/Sr): 1.8
- Coefficient of volumetric shrinkage: 0.50% per 1% change in moisture content
- Fibre saturation point: 28%
A shrinkage ratio of 1.8 indicates a moderate tendency toward cupping. Combined with a volumetric shrinkage coefficient of 0.50%, the wood reacts noticeably to ambient humidity changes. In an epoxy river table, where cured resin remains dimensionally static, any seasonal expansion or contraction of the wood generates shearing stress along the bond line. The wood must be thoroughly acclimatized and dried to your interior target equilibrium moisture content before you cast epoxy against it.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Dialium aubrevillei, Dialium bipidense, Dialium dinklagei, Dialium pachyphyllum, Dialium p.p. | |
| Colour / texture / grain | Red brown; texture medium; grain straight to entangled; interlocked grain marked | |
| Specific gravity (12% MC) | 0.94 | about 58.7 lb/ft³; a 2-inch-thick slab weighs about 9.8 lb per sq ft |
| Monnin hardness (12% MC) | 10.3 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 8.7 % | green to oven-dry |
| Total radial shrinkage | 4.9 % | green to oven-dry |
| Ratio St/Sr | 1.8 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.50 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 28 % | |
| Thermal conductivity | 0.30 W/(m·K) | |
| Crushing strength (12% MC) | 90 MPa | about 13,050 psi |
| Static bending strength (12% MC) | 162 MPa | about 23,500 psi |
| Modulus of elasticity (12% MC) | 22,700 MPa | about 3,292,000 psi |
| Decay (fungi) resistance | Durability class 1 – very durable | |
| Termite resistance | Class D – 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: high 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 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).
Drying Risks and Kiln Behavior
Drying Eyoum requires rigorous patience and control. The CIRAD Tropix data sheet classifies its drying rate as slow, noting a high risk of distortion and a high risk of checking. While there is no known specific risk for casehardening or collapse, thick slabs are prone to surface cracking and warping if dried aggressively. Suggested kiln programs operate within conservative temperature ranges from 45 °C to 65 °C (about 113 °F to 149 °F) to mitigate these risks. Inspecting slabs thoroughly for internal and surface checks prior to the resin pour is essential.
Machining, Tooling, and Gluing
The combination of exceptional density and interlocked grain makes Eyoum demanding on cutting tools. The CIRAD data rates the blunting effect as high, recommending stellite-tipped saw teeth and tungsten carbide tooling to maintain clean edges without burning or tearout. For structural assembly, nailing and screwing properties are good, but pre-boring is strictly necessary to prevent splitting.
Regarding adhesion, the CIRAD technical sheet notes that due to the timber’s high specific gravity, gluing must be performed in strict compliance with the code of practice. The heartwood is classified as Class 4 (not permeable) for preservative treatment, pointing to a tight, non-absorbent pore structure. Preparing clean, freshly abraded surfaces and following your epoxy manufacturer’s data sheet for surface preparation ensures the best mechanical grip along the river channel.
Durability, Environmental Status, and Uses
Eyoum possesses outstanding natural resistance. The heartwood is rated Durability Class 1 (very durable) against fungi, and Class D (durable) against both termites and dry-wood borers (with borer risk limited to the demarcated sapwood). It meets the standards for Use Class 4, signifying suitability in ground contact or fresh water. Environmentally, the timber is not listed in the CITES Appendices (Washington Convention 2025). Traditional industrial end-uses include bridges, heavy flooring, vehicle flooring, railway sleepers, decking, hydraulic works, exterior joinery, turned goods, and sliced veneer.
Is It a Good Epoxy Table Wood?
Eyoum can produce an exceptionally durable, wear-resistant, and visually compelling epoxy table, but it is best suited for experienced craftspeople. Its deep red brown color and live-edge sapwood contrast offer striking aesthetics. However, its high blunting effect, substantial weight (58.7 lb/ft³), slow drying behavior, and high risk of distortion and checking require meticulous stock selection and strict moisture control to avoid stressing the wood-epoxy interface.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because Eyoum heartwood treatability is rated Class 4 (not permeable), deep resin penetration into the wood matrix is limited; scuff-sanding the river edge with coarse abrasive right before casting is critical to maximize mechanical keying. (Source: CIRAD Tropix 7 technical sheet: Eyoum.)