Using Iroko in Wood and Epoxy Tabletops
Iroko (botanical species Milicia excelsa, Milicia regia, and their synonyms Chlorophora excelsa and Chlorophora regia, also known by the trade name Kambala) is an African hardwood frequently evaluated for high-end furniture. Sourced from log diameters ranging from 80 to 100 cm with sapwood bands between 5 and 10 cm thick, it offers wide boards suitable for custom wood and resin projects. The following guide details how this timber behaves in custom river tables and tabletop fabrication based on technical data from the CIRAD Tropix research program.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Milicia excelsa, Chlorophora excelsa (synonymous), Milicia regia, Chlorophora regia (synonymous) | |
| Other trade names | Kambala | |
| Colour / texture / grain | Yellow brown; texture coarse; grain interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.64 | about 40.0 lb/ft³; a 2-inch-thick slab weighs about 6.7 lb per sq ft |
| Monnin hardness (12% MC) | 4.1 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.4 % | green to oven-dry |
| Total radial shrinkage | 3.5 % | green to oven-dry |
| Ratio St/Sr | 1.5 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.44 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 23 % | |
| Thermal conductivity | 0.22 W/(m·K) | |
| Crushing strength (12% MC) | 54 MPa | about 7,830 psi |
| Static bending strength (12% MC) | 87 MPa | about 12,620 psi |
| Modulus of elasticity (12% MC) | 12,840 MPa | about 1,862,000 psi |
| Decay (fungi) resistance | Durability class 1-2 – very durable to 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 3 – not in ground contact, outside | |
| Drying | rate normal; distortion: slight risk; checking: no risk or very slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 55–65 °C | about 131–149 °F |
| Machining | blunting fairly high; saw teeth: stellite-tipped; cutting tools: tungsten carbide | |
| Nailing and screwing | Good | |
| 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 Iroko look like in a live edge slab or tabletop?
Iroko heartwood displays a yellow-brown to more or less dark brown colour accented with golden glints. On slabs, it frequently exhibits darker veins, whereas quartersawn cuts show a distinct ribbon-like aspect. The timber features a coarse texture and a slight interlocked grain. The sapwood is clearly demarcated from the heartwood. Builders should also inspect incoming material for occasional internal inclusions: Iroko logs can contain very hard white calcium carbonate deposits, which are sometimes surrounded by darker rings of wood.
How heavy and hard is Iroko lumber?
At 12% moisture content, Iroko has an average specific gravity of 0.64. In shop terms, this translates to a bulk density of about 40.0 lb/ft³, meaning a 2-inch-thick solid slab weighs approximately 6.7 lb per square foot before carving out a river channel or embedding resin.
Its hardness is measured at 4.1 on the Monnin hardness scale. The Monnin scale is a French standardized test where higher numbers indicate a harder surface (it does not correlate to and must never be converted into a Janka value). A rating of 4.1 places it in a solid medium-hard bracket suitable for tabletop surfaces. Mechanically, mature wood exhibits a crushing strength of 54 MPa (about 7,830 psi), a static bending strength of 87 MPa (about 12,620 psi), and a modulus of elasticity of 12,840 MPa (about 1,862,000 psi).
How stable is Iroko when joined to an epoxy river?
Dimensional stability is critical along the epoxy-wood boundary to prevent stress cracks or joint separation. Iroko exhibits favourable shrinkage numbers: a total tangential shrinkage (St) of 5.4% and a total radial shrinkage (Sr) of 3.5%, yielding a low St/Sr ratio of 1.5. Ratios close to 1.0 denote minimal cupping distortion across board faces.
Its coefficient of volumetric shrinkage is 0.44% per 1% change in moisture content below its fibre saturation point of 23%. Because the wood shows a modest volumetric response to ambient humidity swings, properly dried boards maintain a consistent interface along cured resin pours under normal interior service conditions.
What are the primary drying behaviors and defect risks?
According to CIRAD Tropix testing, Iroko dries at a normal rate. The risk of distortion is rated as slight, while the risk of checking is minimal (classified as no risk or very slight risk). There is no known specific risk for either casehardening or cell collapse. Recommended kiln schedules suggest operating temperatures between 55 °C and 65 °C (about 131 °F to 149 °F).
How abrasive is Iroko on shop tools, and what cutting gear is required?
Fabricating Iroko requires heavy-duty cutting equipment. CIRAD rates the blunting effect on tools as fairly high. Standard steel cutters dull rapidly; stellite-tipped saw teeth and tungsten carbide cutting tools are specifically recommended. The presence of natural calcium carbonate stone deposits in certain boards can severely damage standard blades and router bits. Due to the slightly irregular, interlocked grain, shallow passes are advisable to avoid grain tearing. In addition, Iroko produces very irritant sawdust, making dust collection and personal protection essential during surfacing.
How does Iroko’s chemical composition affect finishing and coatings?
Iroko heartwood contains chlorophorin, a non-saturated phenolic compound that functions as a powerful antioxidant. Because of this extractive, the wood is sometimes resistant to certain standard wood-finishing products. Finishes or varnishes containing siccative oils should be avoided, as the natural antioxidants can inhibit oil drying.
The technical data recommends using synthetic, resin-based coatings free of siccative oil—such as polyurethane varnishes or vinylic formulations—either as the final coat or as an undercoat sealer. Due to the coarse grain structure, surface filling is also recommended prior to topcoat application to obtain a smooth, continuous film across the tabletop.
What is Iroko’s durability rating, CITES status, and intended end uses?
Iroko heartwood has exceptional natural resistance to biological decay. It is classified in Durability Class 1-2 (very durable to durable) against xylophagous fungi, Class D (durable) against termites, and Class D against dry-wood borers. Its heartwood treatability is Class 4 (not permeable). It is categorized for natural durability Use Class 3 (exterior use not in ground contact), and naturally satisfies Use Class 5 for submersion in salt or brackish water under standard NF EN 350, though it is not rated for continuous ground contact (Class 4).
Regarding trade restrictions, Iroko is not listed in the CITES Appendices (Washington Convention 2025). Its primary recognized end uses include high-class cabinetwork, interior and exterior joinery, current furniture, sliced veneer, indoor staircases, ship planking and decking, and heavy flooring.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: CIRAD Tropix notes that spacer sticks often leave marks on Iroko during the seasoning process; a vertical surface drying phase is recommended prior to final stacking to minimize sticker staining. (Source: CIRAD Tropix 7 technical sheet: Iroko.)