Moral Wood in River Table Construction
Moral, known botanically as Maclura tinctoria (synonymous with Chlorophora tinctoria), is a dense Latin American hardwood originating from countries such as Brazil, Colombia, Bolivia, and Mexico. For craftspeople planning a wood and epoxy river build, technical data from the CIRAD Tropix technical sheet provides clear guidance on how this dense species behaves during machining, drying, and resin casting.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Maclura tinctoria, Chlorophora tinctoria (synonymous) | |
| Colour / texture / grain | Brown; texture medium; grain interlocked; interlocked grain marked | |
| Specific gravity (12% MC) | 0.88 | about 54.9 lb/ft³; a 2-inch-thick slab weighs about 9.2 lb per sq ft |
| Monnin hardness (12% MC) | 12.0 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 6.1 % | green to oven-dry |
| Total radial shrinkage | 3.3 % | green to oven-dry |
| Ratio St/Sr | 1.8 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.48 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 18 % | |
| Thermal conductivity | 0.29 W/(m·K) | |
| Crushing strength (12% MC) | 91 MPa | about 13,200 psi |
| Static bending strength (12% MC) | 151 MPa | about 21,900 psi |
| Modulus of elasticity (12% MC) | 21,900 MPa | about 3,176,000 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 4 – not permeable | |
| Use class from natural durability | Class 4 – in ground or fresh water contact | |
| Drying | rate slow; distortion: no risk or very slight risk; checking: no risk or very slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–65 °C | about 127–149 °F |
| Machining | blunting normal; 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).
What does Moral look like in a finished tabletop?
The wood presents a medium texture with marked interlocked grain. The sapwood is clearly demarcated from the heartwood, displaying a greyish-white to pale beige color across a thickness of 4 to 6 cm. The heartwood begins yellow and darkens over time to golden brown or dark brown. On radial surfaces, the interlocked grain reveals a fine ribbon figure, accompanied by a fine, clearly distinct silver figure. In an epoxy river table, this interlocked figure creates significant visual interest along flat-sawn surfaces and exposed edges.
How heavy and hard is Moral wood?
Moral is a dense timber with a specific gravity of 0.88 at 12% moisture content, which equates to about 54.9 lb/ft³. A 2-inch-thick slab weighs approximately 9.2 lb per square foot, requiring solid table bases and strong joinery. In terms of hardness, Moral records a 12.0 on the Monnin hardness scale. Monnin is an established French testing scale where higher numbers denote harder wood; it should not be confused with or converted to a Janka rating. With crushing strength measured at 91 MPa (about 13,200 psi) and static bending strength at 151 MPa (about 21,900 psi), tabletops made with Moral offer exceptional dent resistance.
What are the slab dimensions and CITES regulations?
According to CIRAD Tropix data, log diameters for Moral range from 80 to 120 cm. This provides ample width for wide single-slab projects or live-edge river pairings. For international procurement and shop inventory, builders do not have to navigate CITES restrictions: the species is not listed in the CITES Appendices (Washington Convention 2025).
How stable is Moral next to an epoxy river?
Wood movement is a primary factor in preventing epoxy bond separation. Moral has a total tangential shrinkage of 6.1% and a total radial shrinkage of 3.3%, yielding an St/Sr ratio of 1.8. Its coefficient of volumetric shrinkage is 0.48% per % moisture content, with a fibre saturation point at 18%. While the St/Sr ratio of 1.8 indicates a moderate cupping tendency compared to perfectly balanced species, the modest total shrinkage percentages help the timber stay dimensional once equilibrated to ambient indoor moisture.
What drying risks should builders watch for?
The drying rate for Moral is classified as slow, with suggested kiln schedules between 53 °C and 65 °C (about 127 °F to 149 °F). Despite its density, drying risks are exceptionally low. CIRAD reports no risk or very slight risk of distortion, no risk or very slight risk of checking, and no known specific risk of casehardening or collapse. Slabs that dry slowly without surface checks create cleaner boundaries for deep-pour resin rivers.
How does Moral machine and assemble in the shop?
The timber presents a normal blunting effect on tools, but the CIRAD technical sheet recommends using stellite-tipped saw teeth and tungsten carbide cutting tools to handle its density. When prepping joinery, screwing, or mounting tabletop hardware, nailing and screwing hold well, but pre-boring is necessary. Builders must also note that machining dust may cause irritation, and the wood is chemically active to iron, meaning direct contact with ferrous fasteners or clamps could cause discoloration.
What are the requirements for gluing and epoxy bonding?
CIRAD notes that due to its high specific gravity, gluing must be performed strictly in compliance with the code of practice. When casting resin against Moral river edges, meticulous surface preparation and following the resin manufacturer’s technical instructions are critical to secure a durable mechanical and chemical bond. Additionally, the heartwood is rated Class 4 (not permeable) for treatability, meaning liquid penetration into the cell structure is restricted.
What are the primary end-uses and natural durability ratings?
Moral heartwood has outstanding natural durability: Durability class 1 (very durable) against wood-decay fungi, Class D against dry-wood borers, and Class D against termites. It qualifies for Use class 4 (in ground or fresh water contact) without preservative treatment. Outside of custom furniture or furniture components, CIRAD lists end-uses such as flooring, industrial or heavy flooring, decking, bridges, ship building (planking and deck), indoor staircases, vehicle or container flooring, tool handles, sliced veneer, and turned goods.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because Moral is chemically active to iron, builders should avoid using raw steel fasteners, steel wool, or unbuffered iron clamping cauls during assembly to prevent dark contact staining. (Source: CIRAD Tropix 7 technical sheet: Moral.)