Working with Simpoh in Custom Wood and Epoxy Tabletops
Simpoh encompasses several timber-producing species of the genus Dillenia (such as Dillenia aurea, Dillenia excelsa, Dillenia eximia, Dillenia grandifolia, Dillenia indica, Dillenia ovata, and Dillenia papuana) native to Asia-Oceania. Documented extensively by the CIRAD Tropix technical sheet, this hardwood is harvested in regions including Indonesia, Malaysia, Myanmar, Papua New Guinea, and the Solomon Islands. Simpoh is not listed in the CITES Appendices (Washington Convention 2025), making timber acquisition and trade straightforward from a regulatory perspective.
For custom river table builders, Simpoh presents a unique combination of rich coloration and distinct decorative grain alongside technical hurdles that require careful shop practices.
Appearance, Grain, and Slab Dimensions
Simpoh heartwood displays an attractive red-brown tone, often characterized by an intriguing violet tinge that gradually darkens to a deep chocolate brown over time. Its sapwood, which is clearly demarcated from the heartwood, ranges from light yellowish brown to reddish brown with a typical thickness from 3 to 5 cm. When sawn on the quarter, the wood reveals a decorative silver figure that creates dramatic contrast beneath a clear flood coat or embedded alongside a tinted epoxy river.
The texture of Simpoh is medium, and the grain is straight to slightly interlocked. In log form, diameters range from 80 to 120 cm. This substantial diameter offers woodworkers broad slab widths suitable for full-sized dining tables, conference tops, or dramatic live-edge river pairings.
Density, Hardness, and Structural Strength
Simpoh is a moderately heavy hardwood. At 12% moisture content, its specific gravity averages 0.71, translating to an approximate density of 44.3 lb/ft³. A slab planed to a standard 2-inch thickness weighs roughly 7.4 lb per sq ft, giving completed furniture pieces substantial, solid heft.
Hardness is recorded on the French Monnin scale at 4.2. On the Monnin scale, higher numbers denote harder wood (it is a distinct metric and not equivalent to a Janka rating). A Monnin score of 4.2 indicates a durable surface capable of resisting day-to-day household impacts. Mechanically, mature wood exhibits a crushing strength of 39 MPa (around 5,660 psi), a static bending strength (MOR) of 71 MPa (roughly 10,300 psi), and a modulus of elasticity (MOE) of 17,700 MPa (about 2,567,000 psi), providing sufficient rigidity across wide table spans.
Dimensional Movement and Epoxy River Considerations
Understanding wood movement is essential when locking natural timber against a rigid epoxy casting. Simpoh has a fibre saturation point of 27%. Total tangential shrinkage from green to oven-dry is 7.6%, while total radial shrinkage is 4.4%. The resulting tangential-to-radial shrinkage ratio is 1.7, pointing to moderate cupping tendencies during moisture shifts. Its coefficient of volumetric shrinkage is 0.46% per % change in moisture content.
The CIRAD Tropix data sheet rates the drying rate as normal, but highlights a high risk of distortion and a high risk of checking. There is no known specific risk of collapse or casehardening. Because the timber is prone to checking and warping during drying, slabs must be thoroughly stabilized and verified dry before resin pouring. A sudden shift in moisture content after casting could stress the epoxy-wood bondline, resulting in edge separation or splits.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Dillenia aurea, Dillenia excelsa, Dillenia eximia, Dillenia grandifolia, Dillenia indica, Dillenia ovata, Dillenia papuana, Dillenia p.p. | |
| Colour / texture / grain | Red brown; texture medium; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.71 | about 44.3 lb/ft³; a 2-inch-thick slab weighs about 7.4 lb per sq ft |
| Monnin hardness (12% MC) | 4.2 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 7.6 % | green to oven-dry |
| Total radial shrinkage | 4.4 % | green to oven-dry |
| Ratio St/Sr | 1.7 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.46 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 27 % | |
| Thermal conductivity | 0.24 W/(m·K) | |
| Crushing strength (12% MC) | 39 MPa | about 5,660 psi |
| Static bending strength (12% MC) | 71 MPa | about 10,300 psi |
| Modulus of elasticity (12% MC) | 17,700 MPa | about 2,567,000 psi |
| Decay (fungi) resistance | Durability class 5 – not durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class S – susceptible (risk in all the wood) | |
| Heartwood treatability | Class 1 – easily permeable | |
| Use class from natural durability | Class 1 – inside (no dampness) | |
| Drying | rate normal; distortion: high risk; checking: high risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–65 °C | about 127–149 °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).
Machining, Fastening, and Finishing
Simpoh contains natural silica deposits, which impart a fairly high blunting effect on cutter knives. Fabricators should strictly use stellite-tipped saw teeth and tungsten carbide cutters to avoid burning and rapid edge wear. The slight interlock of the grain can demand light passes during flattening and milling.
When assembling table bases or mechanical brackets, pre-boring is necessary despite good holding power for screws and nails. For surface preparation, CIRAD notes that the wood needs filling before polishing due to its pore structure. Standard traditional end uses include flooring, indoor staircases, mouldings, interior joinery, panelling, and sliced veneer.
Durability and Interior Service Life
Simpoh heartwood falls into Durability Class 5 (not durable against wood-decay fungi). Furthermore, it is classified as Class S (susceptible) to both dry-wood borers and termites. Its natural durability restricts it to Class 1 interior installations where no dampness occurs. Table makers should never specify Simpoh for outdoor or humid environments. On the positive side, the heartwood is Class 1 (easily permeable), meaning it readily accepts stabilizing treatments or sealers.
Is It a Good Epoxy Table Wood?
Simpoh is a viable candidate for interior epoxy river tables, but only if handled with care. Its rich violet-to-chocolate heartwood, quartersawn silver figure, and generous log diameters (up to 120 cm) provide exceptional visual appeal. However, high risks of checking and distortion mean only fully conditioned, kiln-dried slabs should enter the casting mold. Woodworkers must also account for high silica content by tooling with carbide cutters and thoroughly sealing the wood pores.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Simpoh’s natural heartwood treatability is rated as Class 1 (easily permeable), which makes deep-penetrating stabilizing resins and liquid epoxy seal coats absorb into the wood pores far more readily than in denser, impermeable tropical species. (Source: CIRAD Tropix 7 technical sheet: Simpoh.)