Mecrussé Wood Profile for Epoxy Table Builders
Mecrussé (Androstachys johnsonii), also known by the trade name Cimbirre, is an exceptionally heavy African hardwood originating from countries such as Mozambique, Madagascar, and Zimbabwe. According to the CIRAD Tropix technical sheet for the species, it is not listed in the CITES Appendices (Washington Convention 2025). Characterized by high density and fine texture, Mecrussé offers unique mechanical strength for tabletop projects, but its specific physical behaviors require careful preparation before introduction to an epoxy river mold.
Appearance, Figure, and Weight
Mecrussé displays a light brown to reddish-brown heartwood, frequently accented with darker veining. Its sapwood is yellowish-white with a thickness of 1 to 2 cm and is not clearly demarcated from the heartwood. The wood features a fine texture and straight or slightly interlocked grain, providing a clean, tight visual surface across wide tabletop faces.
In terms of weight, Mecrussé is a dense timber with a specific gravity of 0.93 at 12% moisture content. This translates to an approximate density of 58.1 lb/ft³, meaning a 2-inch-thick tabletop slab weighs approximately 9.7 lb per square foot. Mechanical testing shows high resistance to force, with a crushing strength of 67 MPa (about 9,720 psi) and a static bending strength of 163 MPa (about 23,640 psi). Logs typically range from 60 to 80 cm in diameter and do not float in water.
Monnin Hardness Explained
The CIRAD Tropix technical sheet reports a Monnin hardness of 8.7 for Mecrussé at 12% moisture content. Monnin hardness is a French standardized scale based on cylinder indentation where a higher value signifies a harder wood. It is fundamentally different from the American Janka test and cannot be directly converted into Janka pounds-force. At 8.7 on the Monnin scale, Mecrussé ranks as a very hard wood, providing exceptional dent resistance for high-wear furniture surfaces.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Androstachys johnsonii | |
| Other trade names | Cimbirre | |
| Colour / texture / grain | Brown; texture fine; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.93 | about 58.1 lb/ft³; a 2-inch-thick slab weighs about 9.7 lb per sq ft |
| Monnin hardness (12% MC) | 8.7 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 6.2 % | green to oven-dry |
| Total radial shrinkage | 5.7 % | green to oven-dry |
| Ratio St/Sr | 1.1 | 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 | 23 % | |
| Thermal conductivity | 0.30 W/(m·K) | |
| Crushing strength (12% MC) | 67 MPa | about 9,720 psi |
| Static bending strength (12% MC) | 163 MPa | about 23,640 psi |
| Decay (fungi) resistance | Durability class 1 – very durable | |
| Termite resistance | Class D – durable | |
| Dry-wood borer resistance | Class D – durable (heartw. durable but sapw. not | |
| Heartwood treatability | Class 4 – not permeable | |
| Use class from natural durability | Class 4 – in ground or fresh water contact | |
| Drying | rate slow; distortion: slight risk; checking: high risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 45–65 °C | about 113–149 °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).
Shrinkage, Dimensional Stability, and Epoxy River Integration
Dimensional movement is a primary factor when bonding wood slabs to rigid epoxy resin channels. Mecrussé shows a total tangential shrinkage of 6.2% and a total radial shrinkage of 5.7% from green to oven-dry conditions. This results in an exceptionally balanced tangential-to-radial shrinkage ratio (St/Sr) of 1.1.
A ratio close to 1.0 indicates that radial and tangential planes move at nearly identical rates, presenting only a slight risk of distortion or cupping as environmental humidity shifts. Its coefficient of volumetric shrinkage is 0.57% per percent change in moisture content, with a fibre saturation point recorded at 23%. While the low ratio minimizes warp across the interface of an epoxy river, the wood’s high density means any moisture movement generates significant shear stress, reinforcing the need for thorough acclimatization.
Drying Risks, Tooling, and Assembly
Mecrussé dries at a slow rate. While distortion, collapse, and casehardening show slight or no known specific risk, CIRAD Tropix records a high risk of checking. Slabbing or drying too quickly can induce surface checks and end splits. Recommended kiln schedules utilize temperatures between 45 °C and 65 °C (about 113 °F to 149 °F).
For machining, the blunting effect on cutters is rated as normal. However, due to its density, stellite-tipped saw teeth and tungsten carbide cutting tools are specified. Nailing and screwing hold well, but pre-boring is strictly necessary to prevent splitting. Regarding adhesive bonds, the data sheet highlights that due to high specific gravity, gluing must be performed in strict compliance with the code of practice.
Natural Durability and Use Classes
Mecrussé heartwood has outstanding biological durability. It is rated Durability Class 1 (very durable) against wood-decay fungi, Class D (durable) against termites, and Class D against dry-wood borers (though sapwood is not clearly demarcated). Heartwood treatability is Class 4 (not permeable). Its natural resistance places it in Use Class 4 (in ground or fresh water contact), and its exceptional hardness enables it to naturally meet Use Class 5 conditions for marine environments. Typical non-table uses include heavy carpentry, decking, flooring, turned goods, bridges, and hydraulic works.
Practical Pre-Pour Checklist for Mecrussé Slabs
- Inspect for checking: Thoroughly examine all faces and edges for micro-checks or fissures resulting from the species’ high checking risk.
- Verify target moisture content: Ensure the slab has slowly and fully acclimated to shop equilibrium, avoiding green moisture levels above the 23% fibre saturation point.
- Surface preparation with carbide tools: Flatten slabs using sharp tungsten carbide tooling to avoid rough tearout or machine friction on the dense grain.
- Pre-drill mechanical fasteners: If using threaded inserts, mechanical anchors, or tabletop mounting screws, pre-bore every hole to prevent splitting.
- Seal contact edges prior to casting: Because the wood is dense and impermeable (Class 4 treatability), thoroughly brush-seal the live edges with a compatible epoxy coat to lock the interface and improve bond reliability before filling the river.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: CIRAD Tropix lists Mecrussé as a functional substitute for Muhuhu, meaning shops familiar with Muhuhu’s dense working characteristics and turning performance will find very similar shop handling with Mecrussé. (Source: CIRAD Tropix 7 technical sheet: Mecrussé.)