Introduction to Guarea (Bossé Clair)
Guarea, commercially referred to as Scented Guarea or Bossé clair, encompasses African hardwoods primarily from the botanical species Guarea cedrata and Guarea laurentii (along with Guarea p.p.). In commercial grading and trade, G. cedrata and G. laurentii are categorized as light Bossé, distinct from dark Bossé (G. thompsonii). According to the CIRAD Tropix technical sheet, this species is not listed in the CITES Appendices (Washington Convention 2025).
With listed end-uses spanning high-class cabinetwork, furniture components, flooring, interior and exterior joinery, panelling, and ship decking, Guarea offers an intriguing profile for custom furniture makers. However, integrating this timber into deep-pour epoxy river tables requires close attention to its specific physical properties, notably its interlocked grain and natural resin tendencies.
Visual Characteristics and Grain Figure
Guarea heartwood displays an attractive pinkish brown color that contrasts against sapwood that is clearly demarcated, measuring from 5 to 10 cm in thickness on logs between 60 to 100 cm in diameter. The texture of the wood is fine, but the grain structure is distinctly interlocked and marked. Builders frequently observe irregular or wavy grain patterns that produce a slightly moiré figure on sawn faces. Additionally, Guarea cedrata is recognized for its pleasant cedar scent, though it also possesses an active tendency toward natural resin exudation.
Weight, Hardness, and Mechanical Strength
Guarea is a medium-density hardwood. At 12% moisture content, it carries an average specific gravity of 0.63, translating to an air-dry density of approximately 39.3 lb/ft³. For table builders calculating dead load on structural bases, a 2-inch-thick slab weighs roughly 6.6 lb per square foot.
On the French Monnin hardness scale, Guarea rates at 3.5 at 12% moisture content. The Monnin scale operates on an absolute indentation measurement where higher numbers indicate greater surface hardness; it is distinct from and should never be confused with or converted to the Janka scale. Structurally, the wood exhibits a crushing strength of 55 MPa (about 7,980 psi), a static bending strength (MOR) of 95 MPa (about 13,780 psi), and a modulus of elasticity (MOE) of 12,650 MPa (about 1,835,000 psi).
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Guarea cedrata, Guarea laurentii, Guarea p.p. | |
| Colour / texture / grain | Pinkish brown; texture fine; grain interlocked; interlocked grain marked | |
| Specific gravity (12% MC) | 0.63 | about 39.3 lb/ft³; a 2-inch-thick slab weighs about 6.6 lb per sq ft |
| Monnin hardness (12% MC) | 3.5 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 6.8 % | green to oven-dry |
| Total radial shrinkage | 4.1 % | green to oven-dry |
| Ratio St/Sr | 1.7 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.36 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 31 % | |
| Thermal conductivity | 0.21 W/(m·K) | |
| Crushing strength (12% MC) | 55 MPa | about 7,980 psi |
| Static bending strength (12% MC) | 95 MPa | about 13,780 psi |
| Modulus of elasticity (12% MC) | 12,650 MPa | about 1,835,000 psi |
| Decay (fungi) resistance | Durability class 2 – durable | |
| Termite resistance | Class S – susceptible | |
| 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 rapid to normal; distortion: slight risk; checking: slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 55–65 °C | about 131–149 °F |
| Machining | blunting fairly high; saw teeth: stellite-tipped; cutting tools: tungsten carbide | |
| Nailing and screwing | Good | |
| CITES status | This species is not listed in the CITES Appendices (Washington Convention 2025). Notes. * : Common commercial name. G. cedrata and G. laurentii are called light BOSSE; G. thompsonii is called dark BOSSE. |
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 and Movement Next to an Epoxy River
Epoxy resin cures into a rigid plastic matrix that does not expand or contract with ambient humidity. Consequently, pairing wood with an epoxy channel requires low, predictable dimensional movement to prevent delamination or split table joints.
Data from CIRAD documents a total tangential shrinkage of 6.8% and a total radial shrinkage of 4.1% from green to oven-dry status. This results in a tangential-to-radial shrinkage ratio (St/Sr) of 1.7. A ratio of 1.7 indicates a moderate difference between the radial and tangential planes, presenting a slight risk of distortion or cupping under environmental cycling. Its coefficient of volumetric shrinkage is 0.36% per 1% change in moisture content, with a fiber saturation point recorded at 31%. These values mean that once cured and acclimated, properly dried Guarea is reasonably stable, but moisture fluctuations in the surrounding space must still be minimized.
Drying Behavior and Shop Machining
Guarea exhibits a rapid to normal drying rate. Kiln drying schedules generally run between 55 and 65 °C (about 131 to 149 °F). Technical evaluations report only a slight risk of checking and a slight risk of distortion, with no known specific risk of collapse or casehardening. However, Guarea cedrata has a tendency toward resin exudation during drying, which can alter the surface appearance of dried timber.
When machining Guarea slabs, tooling wear is fairly high. Guarea cedrata can contain high to very high silica content, which rapidly dulls standard high-speed steel edges. CIRAD recommends using stellite-tipped saw teeth and tungsten carbide cutting tools. Woodworkers should also run effective dust collection and wear proper personal protection, as the sawdust is an irritant.
Gluing, Finishing, and Durability Considerations
Securing a strong bond between wood edges and an epoxy river requires clean wood fibers. With Guarea, CIRAD notes that gluing Guarea cedrata may be difficult specifically due to resin exudations. Before pouring epoxy or edge-gluing boards, any surface resin must be thoroughly cleaned or prepped per the resin manufacturer's technical data sheet to ensure chemical and mechanical adhesion. For finishing tabletops, CIRAD notes that grain filling is recommended to achieve an optimal final surface finish.
Regarding biological resistance, the heartwood is classified as Durability Class 2 (durable) against fungi and Class D (durable) against dry-wood borers, with borer risk limited to the demarcated sapwood. It is Class S (susceptible) to termites, though G. cedrata is noted as moderately durable. The heartwood is Class 4 (not permeable) to preservative treatment, achieving a natural use class rating of Class 3 (outside, not in ground contact).
Is it a good epoxy table wood?
Guarea (Bossé clair) is a viable, handsome wood for interior epoxy river tables and fine furniture tops, supported by an St/Sr ratio of 1.7 and a fine, moiré-figured pinkish-brown surface. However, it requires careful shop management. The high silica content requires tungsten carbide tooling, and the tendency of Guarea cedrata to exude natural resin poses challenges for epoxy adhesion. If builders carefully address the natural resin on the bonding face and utilize grain filler during top-coating, Guarea performs exceptionally well in custom tabletops.
Sources
- CIRAD Tropix 7 technical sheet: Scented Guarea (Bossé Clair)
- CIRAD Tropix 7 technical sheets (index)
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: CIRAD identifies that dry-wood borer risk is strictly limited to the sapwood, which measures between 5 and 10 cm thick; if you plan to cast live-edge slabs in epoxy where the pale sapwood remains visible, ensure the boards are thoroughly inspected and protected from infestation prior to casting. (Source: CIRAD Tropix 7 technical sheet: Scented Guarea (Bossé Clair).)