Introduction to Angoa for Wood and Epoxy Projects
Angoa (Erismadelphus exsul) is an African hardwood documented by CIRAD Tropix. Sourced from trees with log diameters ranging from 60 to 100 cm, Angoa provides sufficient width for live-edge boards and multi-piece epoxy river table builds. Listed for end-uses such as current furniture components, interior joinery, flooring, and panelling, this species offers a distinctive look for custom wood and resin work when handled with attention to its physical characteristics.
Appearance, Figure, and Surface Texture
The heartwood of Angoa ranges from yellowish to light brown, frequently showing greenish brown marks near the heart. The sapwood is yellowish and is not demarcated from the heartwood. The wood features a coarse texture and grain that can be straight or slightly interlocked. Because of the coarse open texture, the CIRAD technical sheet notes that Angoa needs filling before polishing. In a river table build, this coarse grain requires thorough sealing to prevent outgassing and micro-bubbles along the wood-resin boundary.
Density, Hardness, and Structural Strength
Angoa has a specific gravity of 0.72 at 12% moisture content. In workshop terms, this equals a density of about 44.9 lb/ft³, meaning a 2-inch-thick tabletop slab weighs approximately 7.5 lb per sq ft. This medium-heavy density gives solid, substantial weight to finished furniture bases and frames.
On the French Monnin hardness scale, Angoa scores 4.8 at 12% moisture content. The Monnin scale measures surface resistance where a higher number indicates a harder timber; it should not be converted to or confused with the American Janka scale. A Monnin rating of 4.8 represents moderate hardness, offering good resistance against standard tabletop wear. Structurally, Angoa provides a crushing strength of 56 MPa (about 8,120 psi), a static bending strength of 100 MPa (about 14,500 psi), and a modulus of elasticity of 16,030 MPa (about 2,325,000 psi).
Shrinkage, Stability, and Epoxy River Bonding
When embedding wood slabs alongside a cured epoxy river, dimensional movement must be evaluated carefully. Angoa has a total tangential shrinkage of 9.9% and a total radial shrinkage of 5.6%, yielding a shrinkage ratio of 1.8. Its coefficient of volumetric shrinkage is 0.43% per 1% change in moisture content, with a fibre saturation point of 36%.
The tangential shrinkage value of 9.9% and the 1.8 ratio mean that flat-sawn boards will experience noticeable movement across their width if room humidity fluctuates. If the moisture content is not completely equilibrated to an interior environment before casting, the wood can pull against the rigid epoxy casting or open gaps at the interface. Live edges must be thoroughly stabilized and finished on all sides to control seasonal moisture vapor exchange.
Drying Behavior, Machining, and Natural Durability
CIRAD reports that Angoa dries at a rapid rate. While checking presents no risk or very slight risk and casehardening shows no known specific risk, distortion carries a slight risk, with a noted inclination to twist and cup. Crucially, collapse is recorded as an active risk during drying. Standard suggested kiln schedules run between 53 and 65 °C (about 127 to 149 °F).
In the shop, Angoa performs predictably with standard equipment. The blunting effect on tools is normal, allowing the use of ordinary cutting tools and ordinary or alloy steel sawteeth. Nailing and screwing properties are rated as good. For natural durability, Angoa is classified under Durability class 4 (poorly durable against fungi) and Class S (susceptible to termites and dry-wood borers across all wood). Its heartwood treatability is Class 3 (poorly permeable), and its natural use class is restricted to Class 1 (inside, no dampness). This makes Angoa strictly suitable for interior, dry-climate tabletops. Regarding trade regulations, the species is not listed in the CITES Appendices (Washington Convention 2025).
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Erismadelphus exsul | |
| Colour / texture / grain | Light brown; texture coarse; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.72 | about 44.9 lb/ft³; a 2-inch-thick slab weighs about 7.5 lb per sq ft |
| Monnin hardness (12% MC) | 4.8 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 9.9 % | green to oven-dry |
| Total radial shrinkage | 5.6 % | green to oven-dry |
| Ratio St/Sr | 1.8 | 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 | 36 % | |
| Thermal conductivity | 0.24 W/(m·K) | |
| Crushing strength (12% MC) | 56 MPa | about 8,120 psi |
| Static bending strength (12% MC) | 100 MPa | about 14,500 psi |
| Modulus of elasticity (12% MC) | 16,030 MPa | about 2,325,000 psi |
| Decay (fungi) resistance | Durability class 4 – poorly durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class S – susceptible (risk in all the wood) | |
| Heartwood treatability | Class 3 – poorly permeable | |
| Use class from natural durability | Class 1 – inside (no dampness) | |
| Drying | rate rapid; distortion: slight risk; checking: no risk or very slight risk; collapse: yes; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–65 °C | about 127–149 °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).
Practical Pre-Pour Checklist for Angoa River Tables
- Verify Internal Moisture Content: Confirm that the slab is uniformly dried down to interior equilibrium (around 6% to 12% MC) to prevent rapid shrinkage and cupping against cured resin.
- Inspect for Collapse and Twist: Examine the slab faces for warping, cupping, or cellular collapse that may have developed during its rapid drying cycle.
- Prep Live Edges and Remove Soft Areas: Clear away loose cambium or insect-susceptible sapwood zones with wire brushes, ensuring sound fiber for resin contact.
- Apply a Deep Seal Coat: Coat the coarse, porous surface and edges with a thin epoxy seal coat to satisfy the wood’s open grain and avoid trapped bubbles before the deep pour.
- Machine Flat with Standard Tooling: Plane or flatten both faces using sharp steel or carbide cutters, watching for slight grain tearout on interlocked sections.
- Seal Underside and Fastener Points: Finish all exposed surfaces equally and pre-bore screw holes for base hardware to protect this strictly interior Class 1 wood from ambient moisture changes.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because Angoa’s heartwood is rated as Class 3 (poorly permeable) yet remains Class S (susceptible) to dry-wood borers throughout the entire wood, builders should verify that timber lots have undergone proper heat treatment or preservative processing before bringing them into a conditioned shop space. (Source: CIRAD Tropix 7 technical sheet: Angoa.)