Overview of Mansonia for River Table Builds
Mansonia altissima, commonly known as Mansonia and harvested in Africa, is a fine-textured hardwood frequently specified for high-class cabinetwork, interior joinery, and furniture. For epoxy river table builders, it provides an appealing aesthetic profile that pairs deep, variegated hues with predictable straight grain. Understanding its mechanical and drying characteristics—as documented in the CIRAD Tropix technical sheet—is essential for achieving durable resin bonds and structurally sound tabletop panels.
Appearance, Grain, and Slab Sizing
The heartwood of Mansonia is brown, ranging from yellowish brown to dark grey brown, frequently accented by purplish glints and more or less visible veins. The wood features a fine texture and straight grain, with interlocked grain noted as absent. Its sapwood is clearly demarcated from the heartwood and measures from 2 to 5 cm in thickness.
Log diameters typically range from 40 to 70 cm. In the workshop, this means full live-edge single slabs are moderately sized. For wider conference or dining tables, builders typically bookmatch two live-edge boards around an epoxy river or edge-glue sawn planks to achieve the required tabletop width.
Density, Hardness, and Structural Strength
Mansonia has an average specific gravity of 0.66 at 12% moisture content. According to the CIRAD Tropix data, this yields a density of about 41.2 lb/ft³, meaning a standard 2-inch-thick slab weighs approximately 6.9 lb per square foot. This provides substantial heft for solid furniture without becoming unmanageable during assembly.
On the French Monnin hardness scale, Mansonia scores a 3.8 at 12% moisture content. It is important to remember that Monnin hardness is an empirical French scale where higher numbers reflect harder timber; it is not a Janka rating and should never be converted to one. For tabletop use, a 3.8 Monnin rating indicates solid surface resistance suitable for active dining or office environments. Mechanically, the species exhibits a crushing strength of 60 MPa (about 8,700 psi), a static bending strength (MOR) of 110 MPa (about 15,950 psi), and a modulus of elasticity (MOE) of 13,620 MPa (about 1,975,000 psi).
Shrinkage and Movement Next to Cured Epoxy
Epoxy resin forms a rigid, unyielding interface with wood, making dimensional stability a critical consideration. Mansonia displays a total tangential shrinkage (St) of 7.4% and a total radial shrinkage (Sr) of 4.6%, resulting in an St/Sr ratio of 1.6. The coefficient of volumetric shrinkage is 0.44% per 1% change in moisture content, with a fibre saturation point of 28%.
A shrinkage ratio of 1.6 reflects a moderate, predictable relationship between radial and tangential movement, limiting severe cupping tendencies. However, because volumetric change remains active across varying ambient humidity, the timber must be thoroughly equalized to indoor equilibrium moisture content prior to resin casting to avoid shear strain along the epoxy bond line.
Drying Risks, Machining, and Shop Safety
Mansonia dries at a normal rate. CIRAD Tropix identifies no risk or very slight risk of distortion, and no known specific risk for casehardening or collapse. However, drying presents a high risk of checking. Suggested kiln drying schedules run between 60 °C and 70 °C (about 140 °F to 158 °F). Builders must carefully inspect slabs for fine surface checks or end splits prior to casting.
When working Mansonia in the shop:
- Machining and Tooling: Blunting effect is normal. Standard ordinary or alloy steel saw teeth and ordinary cutting tools produce clean results on its straight grain. Peeling and slicing properties are rated good.
- Fastening: Nailing and screwing properties are rated good, ensuring secure table base attachments.
- Health Warning: The technical sheet notes that Mansonia sawdust may cause dermatitis or mucosa irritation. High-efficiency dust collection and proper skin and respiratory personal protective equipment are mandatory when surfacing or sanding.
Durability and Regulatory Status
The heartwood is classified as Durability class 1 (very durable) against xylophagous fungi under NF EN 350. However, CIRAD notes that it is sensible to white rot (Coriolus versicolor) attacks, giving it a practical classification in class 2 (durable). It is rated Class D (durable) against termites and dry wood borers, with borer risks limited to the sapwood. Heartwood treatability is Class 4 (not permeable). The species is categorized in Use Class 3 (exterior, not in ground contact) and is not listed in the CITES Appendices (Washington Convention 2025).
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Mansonia altissima | |
| Colour / texture / grain | Brown; texture fine; grain straight; interlocked grain absent | |
| Specific gravity (12% MC) | 0.66 | about 41.2 lb/ft³; a 2-inch-thick slab weighs about 6.9 lb per sq ft |
| Monnin hardness (12% MC) | 3.8 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 7.4 % | green to oven-dry |
| Total radial shrinkage | 4.6 % | green to oven-dry |
| Ratio St/Sr | 1.6 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.44 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 28 % | |
| Thermal conductivity | 0.22 W/(m·K) | |
| Crushing strength (12% MC) | 60 MPa | about 8,700 psi |
| Static bending strength (12% MC) | 110 MPa | about 15,950 psi |
| Modulus of elasticity (12% MC) | 13,620 MPa | about 1,975,000 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 3 – not in ground contact, outside | |
| Drying | rate normal; distortion: no risk or very slight risk; checking: high risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 60–70 °C | about 140–158 °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). Notes. Also called MANSONIA. |
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).
Pre-Pour Checklist for Mansonia Slabs
- Check Slab Dimensions: Verify that timber sourced from the 40 to 70 cm log diameter meets your required river opening and width.
- Inspect for Surface Checks: Given the high risk of checking during drying, scan both faces and ends for hairline fractures that require pre-filling or stabilizing.
- Examine the Sapwood Margin: Inspect the clearly demarcated 2 to 5 cm sapwood band for insect activity or mechanical flaws before embedding it along the river edge.
- Verify Moisture Content: Ensure the wood is completely acclimated to target interior conditions to mitigate the 0.44% volumetric shrinkage coefficient before pouring epoxy.
- Don Protective Gear: Set up active dust extraction and wear personal protective equipment to prevent skin and mucosa irritation from fine sanding dust.
- Prepare Mechanical Fasteners: Take advantage of Mansonia’s good screwing properties by planning threaded inserts or mechanical fasteners for the leg base.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: According to the CIRAD Tropix sheet, Mansonia is noted for being resistant to one or several acids, making it a unique candidate for laboratory fittings or specialty surfaces, though its Class 4 impermeable heartwood prevents deep penetration of liquid preservatives. (Source: CIRAD Tropix 7 technical sheet: Mansonia.)