Muirapiranga (Bloodwood) Wood Properties for River Tables
Muirapiranga (Brosimum rubescens), widely traded as Bloodwood, is a dense Latin American hardwood sourced from countries such as Brazil, French Guiana, Guyana, and Suriname. Highly regarded in fine cabinetwork, flooring, turned goods, and stringed instrument bows, this species offers exceptional mechanical stiffness and a striking visual profile. According to technical documentation from CIRAD Tropix, the heartwood is a rich dark red that often presents darker veins, set against a fine texture and straight or slightly interlocked grain. It finishes exceptionally well and takes a beautiful polish.
When planning an epoxy river table or hybrid tabletop, builders must understand the physical demands of this species. Bloodwood is exceptionally heavy, with a specific gravity of 1.10 at 12% moisture content. That equates to an air-dry density of approximately 68.7 lb/ft³, meaning a 2-inch-thick slab weighs roughly 11.4 lb per square foot before resin is added. The tree does not float in water, and logs typically arrive at diameters of 50 to 70 cm with a wide, clearly demarcated sapwood band between 4 and 20 cm thick.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Brosimum rubescens | |
| Other trade names | Bloodwood, Ferolia, Legno satino, Palo de oro, Satinwood | |
| Colour / texture / grain | Dark red; texture fine; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 1.10 | about 68.7 lb/ft³; a 2-inch-thick slab weighs about 11.4 lb per sq ft |
| Monnin hardness (12% MC) | 17.6 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.9 % | green to oven-dry |
| Total radial shrinkage | 4.1 % | green to oven-dry |
| Ratio St/Sr | 1.4 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.59 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 21 % | |
| Thermal conductivity | 0.35 W/(m·K) | |
| Crushing strength (12% MC) | 106 MPa | about 15,370 psi |
| Static bending strength (12% MC) | 162 MPa | about 23,500 psi |
| Modulus of elasticity (12% MC) | 28,130 MPa | about 4,080,000 psi |
| Decay (fungi) resistance | Durability class 2 – 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 slow; distortion: slight risk; checking: slight risk; collapse: no known specific risk; 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).
Hardness, Strength, and Tooling Requirements
Muirapiranga exhibits extreme resistance to indentation. CIRAD Tropix rates its hardness at 17.6 on the Monnin hardness scale. Monnin is a standardized French indentation test where higher numbers reflect harder timber; it is fundamentally distinct from the Janka scale and cannot be directly converted to Janka values. At 17.6, this timber sits among the hardest commercial woods documented.
This extreme hardness carries directly into its crushing strength of 106 MPa (about 15,370 psi) and static bending strength of 162 MPa (about 23,500 psi), paired with an extraordinarily high modulus of elasticity of 28,130 MPa (around 4,080,000 psi). For table builders, these figures mean deflection under heavy tabletop spans is practically nonexistent. However, the trade-off is high tool resistance: CIRAD Tropix notes that machining Muirapiranga requires significant machine power and causes fairly high tool blunting. Stellite-tipped saw teeth and tungsten carbide cutting edges are specifically recommended to mill and flatten slabs cleanly without burning.
Dimensional Movement and Epoxy River Stability
Connecting solid wood slabs to cast epoxy requires predictable shrinkage values. Bloodwood has a fibre saturation point of 21% and a coefficient of volumetric shrinkage of 0.59% per 1% change in moisture content. Total shrinkage from green to oven-dry is 5.9% in the tangential direction and 4.1% in the radial direction, resulting in a tangential-to-radial shrinkage ratio (St/Sr) of 1.4.
Because the St/Sr ratio is relatively low (1.4 is close to 1), Bloodwood displays a low tendency toward severe cross-sectional cupping compared to many other dense tropical species. CIRAD Tropix classifies the risk of distortion and checking during drying as slight, with no known specific risk of internal collapse or casehardening. However, its drying rate is inherently slow. When kiln-drying, suggested temperatures range from 45 °C (113 °F) during initial phases up to 65 °C (149 °F) in late stages.
Gluing, Assembly, and Durability
Fastening and adhesion require strict attention. Nailing and screwing properties are good, but pre-boring is strictly necessary to prevent splitting under hardware fasteners. Due to the very high specific gravity (1.10), CIRAD Tropix emphasizes that gluing must be carried out in rigorous compliance with standard trade practices. Wood surfaces should be freshly planed and trued immediately before resin pours to maximize physical bonding.
Natural durability of the heartwood is very high: it falls into Durability Class 2 (durable) against wood-decay fungi, Class D (durable) against termites, and Class D against dry-wood borers. It is categorized under Use Class 3 for exterior use above ground without ground contact, and its heartwood is impermeable (treatability Class 4). Conversely, the thick sapwood (4 to 20 cm) is very perishable. Regarding international trade controls, Brosimum rubescens is not listed in the CITES Appendices under the 2025 Washington Convention.
Pre-Pour Checklist for Bloodwood River Tabletops
- Inspect and isolate the sapwood: Measure the sapwood band (typically 4 to 20 cm). Because CIRAD notes it is very perishable, remove any compromised or soft live edge sapwood before sealing.
- Verify core moisture content: Ensure the slow-drying wood has acclimated thoroughly to indoor equilibrium moisture content across the full slab thickness before locking it in resin.
- Freshly prep the river face: Because dense hardwoods (specific gravity 1.10) present bonding challenges, mill or scuff the contact face immediately prior to sealing to ensure optimal mechanical grip.
- Equip carbide cutters: Use sharp tungsten carbide tooling and stellite-tipped saws to handle the fairly high blunting effect and high 17.6 Monnin hardness during flattening and edge routing.
- Pre-drill all hardware locations: Never drive structural screws directly into Bloodwood tabletop undersides without pre-boring clearance holes.
- Engineer table bases for high weight: Calculate table base capacity accounting for approximately 11.4 lb per square foot on 2-inch slab sections plus epoxy volume.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: While the dark red heartwood holds Class 2 natural durability against rot and Class D resistance against borers and termites, the CIRAD Tropix data sheet explicitly warns that the sapwood is very perishable and non-durable; if you choose to incorporate the contrasting pale sapwood into a decorative live edge, it must be thoroughly saturated and sealed with low-viscosity resin to prevent localized insect or fungal degradation. (Source: CIRAD Tropix 7 technical sheet: Muirapiranga / Bloodwood.)