African Walnut Characteristics and Appearance
African walnut represents timber from the botanical species Lovoa swynnertonii, Lovoa trichilioides, and its synonym Lovoa klaineana, belonging to the family Meliaceae. Despite its commercial name, CIRAD Tropix technical sheet documentation notes that it should not be confused with true walnut (Juglans species), as only their colors are similar. Log diameters typically range from 60 to 120 cm with a sapwood thickness from 3 to 7 cm. The sapwood is clearly demarcated from the heartwood.
The heartwood displays a brown, yellow-brown, or grey-brown tone, accented with black streaks or veins that present a golden glint under light. Pores contain visible black deposits. The wood features a fine texture and interlocked grain, classified as slight. On quartersawn faces, this slight interlock produces an attractive ribbon-like aspect. Logs may sometimes contain ring shakes or brittleheart, and existing shakes tend to slightly extend during processing.
Density, Hardness, and Mechanical Strength
African walnut is a medium-density hardwood with an average specific gravity of 0.53 at 12% moisture content. In workshop calculations, this translates to roughly 33.1 lb/ft³, meaning a dried 2-inch-thick slab weighs approximately 5.5 lb per square foot. This moderate weight makes it manageable to maneuver across shop benches and casting molds without placing excessive strain on table bases.
Hardness is measured at 2.3 on the Monnin hardness scale at 12% moisture content. The Monnin system is a standardized French test based on cylinder indentation where higher values designate harder timbers; it is entirely distinct from the American Janka test and cannot be directly converted to Janka ratings. Mechanically, mature wood exhibits a crushing strength of 47 MPa (about 6,820 psi), static bending strength of 72 MPa (about 10,440 psi), and a modulus of elasticity of 10,460 MPa (about 1,517,000 psi). Its thermal conductivity is 0.18 W/(m·K).
Shrinkage, Wood Movement, and Epoxy Compatibility
When embedding wood slabs alongside rigid casting resins, seasonal movement must be carefully accounted for to prevent joint separation or shear stress. According to the CIRAD Tropix data, African walnut has a fiber saturation point of 27%. Its total tangential shrinkage is 5.8%, while total radial shrinkage is 3.7%. This yields an St/Sr ratio of 1.6, reflecting balanced dimensional stability and low cupping tendencies during climate shifts. The coefficient of volumetric shrinkage is moderate at 0.43% per 1% change in moisture content.
Drying rates for this species are rapid to normal, carrying only a slight risk of distortion and a slight risk of surface checking. There is no known specific risk of collapse or casehardening. When kiln-drying African walnut, suggested programs operate within a temperature range of 55 to 65 °C (about 131 to 149 °F).
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Lovoa swynnertonii, Lovoa trichilioides, Lovoa klaineana (synonymous) | |
| Colour / texture / grain | Brown; texture fine; grain interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.53 | about 33.1 lb/ft³; a 2-inch-thick slab weighs about 5.5 lb per sq ft |
| Monnin hardness (12% MC) | 2.3 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.8 % | green to oven-dry |
| Total radial shrinkage | 3.7 % | green to oven-dry |
| Ratio St/Sr | 1.6 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.43 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 27 % | |
| Thermal conductivity | 0.18 W/(m·K) | |
| Crushing strength (12% MC) | 47 MPa | about 6,820 psi |
| Static bending strength (12% MC) | 72 MPa | about 10,440 psi |
| Modulus of elasticity (12% MC) | 10,460 MPa | about 1,517,000 psi |
| Decay (fungi) resistance | Durability class 3 to 4 – moderately to poorly durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class D – durable (sapwood demarcated, risk limited | |
| Heartwood treatability | Class 3-4 – poorly or not permeable | |
| Use class from natural durability | Class 2 – inside or under cover (dampness possible) | |
| Drying | rate rapid to normal; distortion: slight risk; checking: 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 normal; saw teeth: ordinary or alloy steel; cutting tools: ordinary | |
| 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).
Tooling, Durability, and Shop Handling
African walnut exhibits normal blunting on ordinary cutting tools and saw blades made of ordinary or alloy steel. However, because of the interlocked grain, woodworkers face difficulties with tearing during planing. Maintaining sharp tools is necessary to achieve a clean face. The resulting fine sawdust may act as an irritant, requiring appropriate shop dust collection and personal protection. Nailing and screwing properties are rated as good.
In terms of durability, the heartwood is classified as durability class 3 to 4 against xylophagous fungi (moderately to poorly durable) and class S (susceptible) against termites. Resistance to dry-wood borers is class D (durable, with risk limited strictly to the demarcated sapwood). Heartwood treatability is class 3-4 (poorly or not permeable). For natural durability, CIRAD Tropix places it in use class 2, covering interior uses or situations under cover where dampness is possible. The wood is not recommended for permanent humidification. Regarding trade regulations, African walnut is not listed in the CITES Appendices (Washington Convention 2025). Its primary commercial end-uses include high-class cabinetwork, interior joinery, furniture components, paneling, seats, turned goods, and sliced veneer.
Pre-Pour Checklist for African Walnut River Tables
- Inspect the slab faces and ends carefully for internal ring shakes or brittleheart, and mark any existing cracks since shakes have a tendency to slightly extend.
- Remove all pale sapwood if insect resistance is critical, as natural borer durability is limited strictly to the heartwood.
- Ensure the timber has equalized below its 27% fiber saturation point to an interior-appropriate moisture content to minimize tangential and radial movement.
- Equip jointers and planers with sharp cutters to eliminate tearout caused by the slightly interlocked grain.
- Wear respiratory dust protection when machining, as the fine sawdust may cause irritation.
- Clean fine pores and black mineral deposits along the casting edge with compressed air to clear debris before mold placement.
- Seal the contact edges thoroughly according to your resin manufacturer’s instructions to prevent air displacement into the deep pour.
- Fasten the tabletop assembly using slotted fasteners to accommodate the wood’s 1.6 shrinkage ratio.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Ring shakes and brittleheart can occur naturally in some African walnut logs, so builder teams should scrutinize raw slab cross-sections before designing an epoxy layout around natural defects. (Source: CIRAD Tropix 7 technical sheet: African walnut.)