Appearance and Visual Character of Ekki
Ekki (Lophira alata, with the botanical synonym Lophira procera) is an African hardwood known for its heavy structural profile and deep coloration. According to the CIRAD Tropix technical sheet, the mature heartwood ranges from dark red to a distinctive purple-brown. The sapwood is clearly demarcated from the heartwood, measuring 2 to 4 cm in thickness, with an intermediate transitional zone located between the two.
For river tables and wide board glue-ups, Ekki offers a coarse texture and a marked interlocked grain. Another visual signature documented by CIRAD Tropix is the presence of white deposits inside the pores. When pairing raw edges with clear or tinted resin, these mineral or organic deposits provide high-contrast detail, though the coarse grain and marked interlock require careful mechanical preparation.
Weight, Monnin Hardness, and Mechanical Strength
Ekki is exceptionally dense. At 12% moisture content, it has an average specific gravity of 1.06, which corresponds to an air-dry weight of approximately 66.2 lb/ft³. In the shop, a standard 2-inch-thick tabletop slab weighs roughly 11.0 lb per square foot. That level of mass demands robust table bases and hardware capable of bearing substantial deadweight.
Hardness for Ekki is measured on the Monnin scale, an established French wood-testing standard where higher values indicate greater hardness. Unlike common North American testing systems, Monnin hardness uses an indentation ratio and is not an equivalent to Janka side hardness. Ekki carries a Monnin hardness rating of 10.7 at 12% moisture content, reflecting a very hard, crush-resistant surface. Its mechanical strength figures are equally massive: a crushing strength of 96 MPa (about 13,920 psi), static bending strength of 162 MPa (about 23,500 psi), and a modulus of elasticity of 21,420 MPa (about 3,107,000 psi).
Shrinkage, Stability, and Epoxy River Table Dynamics
Despite its strength, the CIRAD Tropix sheet classifies Ekki overall as a poorly stable wood. It exhibits total tangential shrinkage of 10.3% and total radial shrinkage of 7.3%, producing a tangential-to-radial shrinkage ratio of 1.4. Its coefficient of volumetric shrinkage is 0.69% per 1% change in moisture content, with a fiber saturation point of 28%.
In a wood-and-epoxy assembly, high volumetric shrinkage means that any moisture swing after casting will cause significant dimensional movement. A ratio of 1.4 indicates a moderate cupping risk across wide boards, but CIRAD notes an important structural behavior: small-section, high-slenderness pieces (such as thin decking) are not very stable, whereas large-section pieces remain relatively stable. For river table builders, this means thick, broad slabs will hold their form better than thin ripped boards, provided the core is properly conditioned.
Drying Challenges, Machining, and Gluing
Working with Ekki presents distinct shop hurdles:
- Drying risks: 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. CIRAD recommends a sheltered surface pre-drying period of 3 to 4 months before kiln drying. Slabs thicker than 38 mm are noted as very difficult to dry. Suggested kiln schedule temperatures range from 45 to 65 °C (113 to 149 °F).
- Tool wear and machining: Ekki imposes a fairly high blunting effect on cutters. Saws require stellite-tipped teeth, and cutting tools must be tungsten carbide. The wood requires significant machine power, and the marked interlocked grain creates difficulties during surface planing.
- Fasteners and adhesion: Direct nailing and screwing is good, but pre-boring is strictly necessary. Because of Ekki’s 1.06 specific gravity, CIRAD notes that gluing must be performed specifically in compliance with structural codes of practice. Heartwood treatability is classified as Class 4 (not permeable).
Natural Durability, CITES Status, and End-Uses
Ekki’s heartwood exhibits exceptional natural resistance: Class 2 (durable) against wood-decay fungi, Class D (durable) against termites, and Class D (durable) against dry-wood borers (with risk limited to sapwood). It meets Use Class 4 standards for direct ground or freshwater contact. The species is not listed in the CITES Appendices (Washington Convention 2025).
Its listed industrial and structural end-uses include bridges (both submerged and dry parts), fresh and seawater hydraulic works, industrial flooring, heavy carpentry, vehicle flooring, indoor staircases, cooperage, sleepers, and structures resistant to acids.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Lophira alata, Lophira procera (synonymous) | |
| Colour / texture / grain | Dark red; texture coarse; grain interlocked; interlocked grain marked | |
| Specific gravity (12% MC) | 1.06 | about 66.2 lb/ft³; a 2-inch-thick slab weighs about 11.0 lb per sq ft |
| Monnin hardness (12% MC) | 10.7 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 10.3 % | green to oven-dry |
| Total radial shrinkage | 7.3 % | green to oven-dry |
| Ratio St/Sr | 1.4 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.69 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 28 % | |
| Thermal conductivity | 0.34 W/(m·K) | |
| Crushing strength (12% MC) | 96 MPa | about 13,920 psi |
| Static bending strength (12% MC) | 162 MPa | about 23,500 psi |
| Modulus of elasticity (12% MC) | 21,420 MPa | about 3,107,000 psi |
| Decay (fungi) resistance | Durability class 2 – 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 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).
Practical Pre-Pour Checklist for Ekki Slabs
- Verify that the core moisture content of the slab is stable and thoroughly equilibrated to your indoor climate, especially if working with stock over 38 mm thick.
- Inspect the slab faces and live edges for drying checks or surface distortion that may have formed during its slow seasoning phase.
- Mill the lumber using high-powered machinery outfitted with tungsten-carbide knives to counter the marked interlocked grain and prevent severe planing tearout.
- Clean out all coarse pores and white mineral deposits along the casting perimeter with compressed air and wire brushing to ensure mechanical clearance for epoxy adhesion.
- Pre-bore all holes before attempting to drive mechanical fasteners, threaded inserts, or leg mounting hardware into the dense, 10.7 Monnin wood.
- Prepare the contact edges strictly according to standard wood-gluing best practices, recognizing that Class 4 impermeable, dense hardwoods offer low natural resin penetration.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: For projects subject to moisture exposure, pay close attention to the transitional zone between the sapwood and heartwood; CIRAD Tropix notes that this intermediate wood has variable durability and must be removed for applications involving permanent humidification. (Source: CIRAD Tropix 7 technical sheet: Ekki.)