Working with Essia in Custom Wood and Epoxy Tabletops
Essia (Petersianthus macrocarpus, with botanical synonyms Combretodendron africanum and Petersia africana) is a dense African hardwood documented in the CIRAD Tropix technical sheet. Known for rich coloration and striking grain figures, it offers unique visual character for furniture builders. However, its physical density and drying tendencies present specific challenges when joined with epoxy resin.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Petersianthus macrocarpus, Combretodendron africanum (synonymous), Petersia africana (synonymous) | |
| Colour / texture / grain | Red brown; texture medium; grain interlocked; interlocked grain marked | |
| Specific gravity (12% MC) | 0.80 | about 49.9 lb/ft³; a 2-inch-thick slab weighs about 8.3 lb per sq ft |
| Monnin hardness (12% MC) | 4.0 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 9.2 % | green to oven-dry |
| Total radial shrinkage | 4.7 % | green to oven-dry |
| Ratio St/Sr | 2.0 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.53 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 36 % | |
| Thermal conductivity | 0.26 W/(m·K) | |
| Crushing strength (12% MC) | 57 MPa | about 8,270 psi |
| Static bending strength (12% MC) | 103 MPa | about 14,940 psi |
| Modulus of elasticity (12% MC) | 12,870 MPa | about 1,867,000 psi |
| Decay (fungi) resistance | Durability class 3 – moderately durable | |
| Termite resistance | Class M – moderately durable | |
| Dry-wood borer resistance | Class D – durable (sapwood demarcated, risk limited | |
| Heartwood treatability | Class 3 – poorly permeable | |
| Use class from natural durability | Class 2 – inside or under cover (dampness possible) | |
| Drying | rate slow; distortion: high risk; checking: high risk; collapse: yes; 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 Essia look like, and what slab widths are available?
Essia heartwood is red brown, though it can display a variable aspect ranging from yellowish pink to red brown. The wood features a medium texture with marked interlocked grain that may be straight or wavy. In decorative cuts, figure can appear mottled, striated, veined, or moiré. Log diameters range from 60 to 100 cm, which yields usable slab widths for dining tables and river builds. The sapwood is clearly demarcated, wide (measuring from 8 to 10 cm thick), and distinctly lighter. Builders working with unseasoned lumber should also anticipate an unpleasant odour when green.
How heavy and hard is Essia?
Essia is a heavy wood with an average specific gravity of 0.80 at 12% moisture content. That places its weight at about 49.9 lb/ft³, meaning a 2-inch-thick tabletop slab weighs approximately 8.3 lb per sq ft. In terms of mechanical strength, CIRAD reports a crushing strength of 57 MPa (about 8,270 psi), a static bending strength of 103 MPa (about 14,940 psi), and a modulus of elasticity of 12,870 MPa (about 1,867,000 psi).
Its hardness measures 4.0 on the Monnin hardness scale. The Monnin scale is a French testing standard where higher values indicate harder timber; it is not a Janka rating and should never be treated as one. A Monnin rating of 4.0 places Essia in a solid medium-hard bracket suitable for durable furniture tops.
How does Essia move next to an epoxy river?
Dimensional movement is a critical factor when pairing wood with rigid epoxy castings. Essia displays total tangential shrinkage of 9.2 % and total radial shrinkage of 4.7 %, giving a tangential-to-radial shrinkage ratio of 2.0. Its coefficient of volumetric shrinkage is 0.53 % per % MC, with a fibre saturation point of 36 %.
A shrinkage ratio of 2.0 indicates a noticeable tendency toward cupping. Combined with a relatively high volumetric shrinkage coefficient, any interior humidity swing that alters slab moisture will exert substantial stress along the epoxy-wood boundary. To avoid seam failure or cracking, boards must be dried thoroughly and stabilized before pouring.
What are the drying risks for Essia slabs?
Drying Essia requires extreme patience. CIRAD lists the drying rate as slow, with a high risk of distortion, a high risk of checking, and a confirmed risk of collapse (though casehardening carries no known specific risk). In fact, CIRAD notes that kiln drying is very difficult and recommends drying thin dimensions rather than thick timber.
For thick dimensions, quartersawn stock is recommended to minimize defect risks. When kiln schedules are used, CIRAD outlines suggested temperatures between 53 and 65 °C (about 127 to 149 °F). Rushing thick live-edge slabs through drying will almost certainly cause internal checking or warping.
How does Essia machine, plane, and cut?
Essia exerts a normal blunting effect on cutting edges, but tooling should be matched to its density. CIRAD recommends stellite-tipped saw teeth and tungsten carbide cutting tools. The marked interlocked grain complicates machining; surface tearout is a common hazard, especially during planing operations. Light passes and sharp carbide cutters are essential to achieve a clean profile.
What assembly and gluing rules apply to Essia tabletops?
Because of its dense structure, pre-boring is strictly necessary for all nailing and screwing to prevent splitting, particularly with thin dimensions. In addition, CIRAD explicitly warns that because of Essia’s high specific gravity, gluing must be performed strictly in compliance with the code of practice. For epoxy river projects, slabs must be cleanly planed, free of surface contamination, and bonded following the resin manufacturer’s technical data sheet.
Is Essia naturally durable, and does it face trade restrictions?
Essia heartwood is classified as durability class 3 (moderately durable) against wood-decay fungi, class M (moderately durable) against termites, and class D (durable) against dry-wood borers. Its heartwood treatability is class 3 (poorly permeable), and its natural durability earns it a class 2 rating for use inside or under cover where dampness is possible. In commercial trade, Essia is utilized for heavy carpentry, sliced veneer, and vehicle or container flooring. Essia is not listed in the CITES Appendices (Washington Convention 2025).
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: If you plan to showcase Essia’s natural live edge, keep in mind that CIRAD warns the wide sapwood (8 to 10 cm thick) is sensible to insect attacks, while whole logs have low durability requiring prompt preservative treatment. (Source: CIRAD Tropix 7 technical sheet: Essia.)