Ovangkol in Custom River Table Builds
Ovangkol (Guibourtia ehie), also known in the timber trade as Mozambique or Ovengkol, is an African hardwood originating from nations such as Cameroon, Côte d’Ivoire, Gabon, and Ghana. For builders crafting custom epoxy river tables and solid tabletops, it offers an arresting presentation. According to the CIRAD Tropix technical sheet, the heartwood ranges from yellow-brown to dark brown, highlighted by grey to blackish veins and warm copper glints. When quartersawn, Ovangkol can present an eye-catching moiré figure. Its sapwood is clearly demarcated, typically measuring between 4 and 7 cm in thickness, and the wood possesses a fine texture with slightly interlocked grain.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Guibourtia ehie | |
| Other trade names | Mozambique, Ovengkol | |
| Colour / texture / grain | Yellow brown; texture fine; grain interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.82 | about 51.2 lb/ft³; a 2-inch-thick slab weighs about 8.5 lb per sq ft |
| Monnin hardness (12% MC) | 7.5 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 8.0 % | green to oven-dry |
| Total radial shrinkage | 3.9 % | green to oven-dry |
| Ratio St/Sr | 2.1 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.57 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 24 % | |
| Thermal conductivity | 0.27 W/(m·K) | |
| Crushing strength (12% MC) | 69 MPa | about 10,010 psi |
| Static bending strength (12% MC) | 127 MPa | about 18,420 psi |
| Modulus of elasticity (12% MC) | 21,470 MPa | about 3,114,000 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 3 – poorly permeable | |
| Use class from natural durability | Class 4 – in ground or fresh water contact | |
| Drying | rate normal to slow; distortion: slight risk; checking: slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–62 °C | about 127–144 °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).
Weight, Hardness, and Mechanical Strength
Ovangkol is a dense, stout hardwood. At 12% moisture content, it has an average specific gravity of 0.82, which equates to a density of about 51.2 lb/ft³. In practical workshop terms, a 2-inch-thick slab weighs roughly 8.5 lb per square foot. Builders designing large dining tables must ensure substantial base joinery and robust legs to manage the resulting mass.
On the French Monnin hardness scale, mature Ovangkol rates at 7.5 at 12% moisture content. The Monnin system measures timber hardness by the depth of an indentation made by a cylindrical steel tool, where a higher number denotes a harder surface. (Note that Monnin numbers are an independent scale and cannot be converted to Janka values.) This level of hardness provides excellent crush resistance for functional tabletops, backed by a crushing strength of 69 MPa (about 10,010 psi), a static bending strength of 127 MPa (about 18,420 psi), and a modulus of elasticity of 21,470 MPa (about 3,114,000 psi).
Dimensional Movement and River Stability
Whenever wood is permanently bonded to rigid epoxy resin, dimensional stability dictates long-term performance. Ovangkol has a total tangential shrinkage of 8.0% and a total radial shrinkage of 3.9%, yielding an St/Sr ratio of 2.1. Its coefficient of volumetric shrinkage is 0.57% per 1% change in moisture content, with a fiber saturation point of 24%.
Because the tangential shrinkage is double the radial shrinkage, plainsawn sections will move noticeably more than quartersawn boards when indoor humidity fluctuates. To minimize stress along the epoxy-to-wood bondline, timber must be dried thoroughly to reach equilibrium moisture content before casting. Any dimensional movement after pouring puts shear strain on the resin interface, making proper conditioning vital.
Drying, Tooling, and Shop Working Notes
CIRAD records Ovangkol’s drying rate as normal to slow, with only a slight risk of distortion and a slight risk of checking. There is no known specific risk of casehardening or collapse. For kiln operations, Tropix suggests run temperatures ranging from 53 to 62 °C (about 127 to 144 °F).
In the shop, Ovangkol requires dedicated power due to its high density and slightly interlocked grain:
- Cutting and Planing: The blunting effect on tools is fairly high. Stellite-tipped saw teeth and tungsten carbide cutting edges are strongly recommended.
- Surface Efflorescence: Sawn boards sometimes develop a white efflorescence or white deposits on the surface. These can be removed prior to epoxy work with a warm water wash.
- Fasteners: Nailing and screwing properties are rated as good, but pre-boring is necessary to prevent splitting.
- Gluing: Because of the timber’s high specific gravity, CIRAD notes that gluing must be carried out carefully and in strict compliance with proper trade practice.
Durability, Environmental Status, and End-Uses
Ovangkol heartwood exhibits exceptional natural resistance against biological threats. It achieves Durability Class 2 (durable) against wood-decay fungi, Class D (durable) against termites, and Class D against dry-wood borers (with risks limited to any remaining sapwood). The heartwood is poorly permeable (Class 3 treatability) and qualifies for Use Class 4, covering applications in ground or fresh water contact. Environmental regulations are straightforward: Ovangkol is not listed in the CITES Appendices (Washington Convention 2025). Its recognized industrial end-uses include high-class cabinetwork, musical instruments, flooring, stairs, exterior joinery, decking, sliced veneer, turned goods, and environments requiring resistance to one or several acids.
Practical Pre-Pour Checklist for Ovangkol Slabs
- Confirm Equilibrium Moisture: Test the slab cores to ensure they have fully dried down to the target moisture level suitable for your climate before sealing or pouring.
- Wash Away Surface Deposits: Inspect the live edges and faces for white efflorescence; scrub these areas clean with warm water and let the wood dry completely.
- Tune Tooling and Cutters: Equip planers, jointers, and router sleds with fresh carbide cutters or stellite tooling to handle the wood’s density and high blunting effect without burning the grain.
- Roughen and Clean the Bondline: Thoroughly abrade the river edge to provide mechanical tooth, as dense hardwoods require an immaculate surface profile for adhesive bonding.
- Pre-Seal the Live Edge: Apply a thin initial seal coat of resin per the resin maker’s data sheet to lock the pores and prevent trapped outgassing bubbles in the deep river pour.
- Pre-Drill Table Mounting Points: Plan out base fastener locations in advance, drilling oversized pilot holes with slotted brackets to accommodate seasonal movement across the width.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: If retaining the sapwood for aesthetic contrast on a live edge, remember that CIRAD Tropix notes dry-wood borer risk is limited specifically to the sapwood, while the heartwood is naturally resistant (Class D); ensure any sapwood edges are thoroughly checked and completely encapsulated in resin. (Source: CIRAD Tropix 7 technical sheet: Ovangkol.)