Working with Alep in Wood and Epoxy Builds
Alep (Desbordesia insignis, with synonyms Desbordesia glaucescens and Desbordesia pierreana) is an African hardwood notable for its exceptional mass and mechanical strength. Originating from western and central Africa, it is primarily utilized for heavy industrial applications like decking, sleepers, bridges, and hydraulic works. When considered for custom woodworking such as epoxy river tables and solid composite tabletops, Alep provides an ultra-dense, hard-wearing surface, but its pronounced shrinkage rates and density demand careful shop preparation based on data from the CIRAD Tropix technical sheet.
Appearance, Grain, and Slab Dimensions
Alep heartwood displays an initial yellow-brown tone that turns to dark brown upon exposure to air, often accented by a variable number of dark veins. The sapwood is clearly demarcated from the heartwood, measuring from 5 to 8 cm in thickness. The wood has a fine texture, a straight grain, and an absence of interlocked grain. According to the CIRAD Tropix data, log diameters range from 90 to 100 cm, offering wide slab potential for conference tables and full-width river pours without requiring extensive edge-gluing.
Density, Hardness, and Mechanical Strength
Alep is an exceptionally heavy timber. At 12% moisture content, its specific gravity averages 1.05, which translates to a density of about 65.6 lb/ft³. A standard 2-inch-thick tabletop slab weighs approximately 10.9 lb per square foot. The CIRAD Tropix technical sheet rates Alep with a Monnin hardness of 10.9. The Monnin scale is an established French hardness measurement where higher numerical values indicate greater resistance to indentation; it is not a Janka rating and should never be read as one.
Mechanically, Alep exhibits tremendous load resistance. Its crushing strength is 80 MPa (about 11,600 psi), with a static bending strength of 157 MPa (about 22,770 psi) and a modulus of elasticity of 23,390 MPa (about 3,392,000 psi). For tabletop design, this high modulus means minimal deflection over wide spans, though the shear mass places substantial demands on table bases and mounting hardware.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Desbordesia insignis, Desbordesia glaucescens (synonymous), Desbordesia pierreana (synonymous) | |
| Colour / texture / grain | Yellow brown; texture fine; grain straight; interlocked grain absent | |
| Specific gravity (12% MC) | 1.05 | about 65.6 lb/ft³; a 2-inch-thick slab weighs about 10.9 lb per sq ft |
| Monnin hardness (12% MC) | 10.9 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 10.9 % | green to oven-dry |
| Total radial shrinkage | 6.8 % | green to oven-dry |
| Ratio St/Sr | 1.6 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.67 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 28 % | |
| Thermal conductivity | 0.33 W/(m·K) | |
| Crushing strength (12% MC) | 80 MPa | about 11,600 psi |
| Static bending strength (12% MC) | 157 MPa | about 22,770 psi |
| Modulus of elasticity (12% MC) | 23,390 MPa | about 3,392,000 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 3 – poorly 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 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).
Dimensional Stability and the Epoxy Interface
The primary hurdle when pairing Alep with epoxy resin is moisture movement. Alep has a fiber saturation point of 28%. Its total tangential shrinkage is 10.9%, while total radial shrinkage is 6.8%, resulting in an St/Sr ratio of 1.6. Its coefficient of volumetric shrinkage is 0.67% per 1% change in moisture content. Because the total tangential shrinkage is high, any moisture change after casting creates strong forces against an immovable epoxy river.
If wood movement occurs after curing, the stress along the wood-resin joint can lead to edge shear, boundary fractures, or checking within the wood itself. Slabs must be fully dried to indoor equilibrium moisture content before any resin is mixed or poured.
Drying Risks, Tool Wear, and Gluing
Drying Alep requires patience and close control. The CIRAD Tropix sheet indicates that the drying rate is slow, with a high risk of distortion and a high risk of checking. There is no known specific risk of collapse or casehardening, but logs must be sawn quickly after felling to prevent cracks. Suggested kiln schedules use temperatures ranging from 45 to 65 °C (about 113 to 149 °F).
Machining Alep requires high power. The blunting effect on cutters is fairly high; CIRAD recommends stellite-tipped saw teeth and tungsten carbide cutting tools. For joinery and leg mounting, nailing and screwing hold well, but pre-boring is strictly necessary to prevent splitting. The technical sheet highlights that due to the very high specific gravity, gluing must be performed in strict compliance with the code of practice. For epoxy tabletops, this means deep pore preparation, thorough dust extraction, and generous seal coats to maximize bond strength on this dense, poorly permeable wood (Class 3 treatability).
In terms of durability, Alep heartwood is rated Durability Class 1 (very durable) against fungi and Class D (durable) against dry-wood borers and termites. Regarding international trade rules, this species is not listed in the CITES Appendices (Washington Convention 2025).
Pre-Pour Checklist for Alep River Tables
- Verify that the core moisture content of the slab is stabilized and fully acclimated to the climate-controlled indoor space where the table will reside.
- Inspect the slab surfaces thoroughly for any checking or hairline splits caused by the slow, high-risk drying process.
- Square and prepare joint edges using sharp tungsten carbide cutters or stellite-tipped tooling to avoid burnishing the dense wood fibers.
- Remove all sapwood or inspect it closely, as the natural borer resistance applies primarily to the heartwood and sapwood is clearly demarcated.
- Vacuum the wood pores completely to clear all fine dust generated from machining.
- Apply a thin seal coat of epoxy across all contact faces and river edges in accordance with resin manufacturer guidelines to seal the poorly permeable surface and prevent outgassing bubbles.
- Allow the seal coat to cure per product specifications before securing the wood inside the mold for the deep pour.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because CIRAD Tropix notes that Alep wood turns from yellow-brown to dark brown upon exposure to air, builders should anticipate natural darkening along the river interface and top surface over time, which will increase contrast against light-colored or clear epoxy pours. (Source: CIRAD Tropix 7 technical sheet: Alep.)