Mora Timber Profile for Epoxy River Tables
Mora covers several species from Latin America, notably Mora excelsa, Mora gonggrijpii, Mora megistosperma, and Mora paraensis. According to the CIRAD Tropix technical sheet, the wood produces a pinkish-brown to red-brown heartwood, occasionally figured with thin darker veins. The sapwood is clearly demarcated and measures from 5 to 15 cm thick on logs ranging from 60 to 150 cm in diameter. Mora has a medium texture paired with marked interlocked grain.
This is an extraordinarily dense wood. With a specific gravity of 1.03 at 12% moisture content, it does not float in water. In standard shop dimensions, that equals roughly 64.3 lb/ft³, meaning a 2-inch-thick tabletop slab weighs about 10.7 lb per square foot before pouring any resin. The wood is exceptionally hard, registering 8.6 on the French Monnin hardness scale (where higher numbers indicate greater hardness; this scale must not be confused with or converted to Janka). Coupled with a static bending strength of 141 MPa (about 20,450 psi) and a modulus of elasticity of 18,940 MPa (about 2,747,000 psi), Mora creates an unyielding table foundation, but demands careful handling at the epoxy boundary.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Mora excelsa, Mora gonggrijpii, Mora megistosperma, Mora paraensis | |
| Colour / texture / grain | Red brown; texture medium; grain interlocked; interlocked grain marked | |
| Specific gravity (12% MC) | 1.03 | about 64.3 lb/ft³; a 2-inch-thick slab weighs about 10.7 lb per sq ft |
| Monnin hardness (12% MC) | 8.6 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 10.0 % | green to oven-dry |
| Total radial shrinkage | 6.5 % | green to oven-dry |
| Ratio St/Sr | 1.5 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.68 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 26 % | |
| Thermal conductivity | 0.33 W/(m·K) | |
| Crushing strength (12% MC) | 80 MPa | about 11,600 psi |
| Static bending strength (12% MC) | 141 MPa | about 20,450 psi |
| Modulus of elasticity (12% MC) | 18,940 MPa | about 2,747,000 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 3-4 – poorly or 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: yes; 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).
Pros and Cons for River Table Builders
Pros
- High Natural Durability: Rated Durability class 1 (very durable) against wood-decay fungi, Class D against termites, and Class D against dry-wood borers (with borer risk limited to sapwood).
- Structural Rigidity: Exceptional crushing strength of 80 MPa (about 11,600 psi) and high modulus of elasticity ensure minimal tabletop deflection over wide spans.
- Subtle Figure: Warm red-brown color tone with marked interlocked grain and occasional darker striping creates a bold contrast against clear or tinted epoxy.
- Unrestricted Trade: Mora is not listed in the CITES Appendices (Washington Convention 2025).
- Moderate Cupping Ratio: A tangential-to-radial shrinkage ratio (St/Sr) of 1.5 indicates a balanced directional shrinkage profile.
Cons
- Severe Drying Hazards: High risk of distortion, high risk of checking, and prone to collapse if dried improperly.
- High Overall Shrinkage: Total tangential shrinkage is 10.0% and radial is 6.5%, with a coefficient of volumetric shrinkage of 0.68% per % MC, exerting heavy stress on rigid resin joints during moisture shifts.
- Extreme Weight: At approximately 64.3 lb/ft³, completed river tables require heavy-duty bases and hardware.
- Difficult Machining: Hardness and marked interlocked grain cause high tool wear and make clean surfacing difficult.
- Gluing Sensitivity: Heartwood is poorly or not permeable (treatability Class 3-4), requiring strict adherence to gluing best practices.
Build Notes for Wood and Epoxy Fabrication
Slab Selection and Inspection
Log diameters range from 60 to 150 cm, offering wide material suitable for single-slab river channels. However, because CIRAD Tropix notes that the heartwood is prone to collapse and checking during drying, every board must be inspected for internal separations and honeycombing before work begins. The sapwood is 5 to 15 cm thick and clearly demarcated from the red-brown heartwood. Because sapwood is susceptible to dry-wood borers, verify that any live edge incorporating sapwood is sound and free of insect activity.
Drying and Equilibrium Moisture
Mora exhibits a slow drying rate. The fiber saturation point is 26%. Suggested kiln schedules range between 45 °C and 65 °C (about 113 °F to 149 °F), calling for slow, careful moisture extraction to prevent high-risk distortion and checking. Because the coefficient of volumetric shrinkage is high at 0.68% per % MC, bringing the wood to a stable indoor equilibrium before casting is mandatory. If wood is cast while wet, tangential contraction (up to 10.0% total) will break adhesive bonds along the river bank.
Machining and Surfacing
CIRAD notes that Mora is hard to saw due to its high density and marked interlocked grain. The blunting effect on cutting edges is fairly high. Machine slabs using stellite-tipped saw teeth and tungsten-carbide knives. Flattening slabs on a CNC or router sled requires slow feed rates and light passes to prevent tearout along the interlocked fibers. For hardware installation and mounting table bases, nailing and screwing quality is good, but pre-boring is strictly necessary to prevent splitting.
Sealing, Gluing, and Finishing
The CIRAD sheet highlights that due to Mora’s very high specific gravity, gluing must be performed strictly in compliance with established codes of practice. Heartwood treatability is Class 3-4 (poorly or not permeable). Sand the bonding edges thoroughly to expose clean, fresh wood fibers, and clear away all sanding dust. Apply an epoxy seal coat to the live edge to seal surface pores and reduce outgassing before executing deep casting pours. Mora is traditionally utilized in demanding structural end-uses such as heavy flooring, bridges, hydraulic works, and tool handles, confirming that once properly dried and sealed, it provides an ultra-durable tabletop surface.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: For mounting heavy steel table legs into Mora slabs, always pre-bore pilot holes to the exact root diameter of your fasteners; at an 8.6 Monnin hardness and 80 MPa crushing strength, driving screws without full-depth pilot holes will shear steel fastener heads clean off. (Source: CIRAD Tropix 7 technical sheet: Mora.)