Introduction to Perupok for Custom River Tables
Perupok refers to timber harvested from several species within the genus Lophopetalum, primarily Lophopetalum javanum, Lophopetalum multinervium, Lophopetalum wightianum, and related species (Lophopetalum p.p.) belonging to the family Celastraceae. Originating from Asia-Oceania—including major producing nations such as India, Indonesia, Malaysia, Thailand, and Viet Nam—this timber yields logs with diameters ranging from 60 to 100 cm. For woodworkers building custom epoxy river tables and live-edge furniture, this log diameter offers ample width for wide river-table banks, structural boards, and multi-slab bookmatches.
Perupok is not listed in the CITES Appendices under the Washington Convention (2025). According to technical data published by the CIRAD Tropix research program, Perupok presents a fine texture with straight or slightly interlocked grain. Visually, the wood exhibits a yellow-brown tone once seasoned. Freshly cut heartwood displays a light straw, yellow, or pink hue that transitions to light yellow-brown upon drying. CIRAD notes that the sapwood is yellow and not demarcated from the heartwood, and the planed wood surface develops an attractive lustrous sheen, making it an appealing domestic or commercial tabletop surface.
Weight, Hardness, and Mechanical Strength
Perupok falls into a medium-density hardwood profile. CIRAD reports an average specific gravity of 0.55 at 12% moisture content, which corresponds to a density of approximately 34.3 lb/ft³. For shop planning and base design, a standard 2-inch-thick tabletop slab weighs roughly 5.7 lb per square foot before resin channels are cut.
When assessing surface durability and dent resistance, CIRAD evaluates Perupok using the Monnin hardness test rather than the North American Janka standard. Monnin hardness is a French test measuring cylinder indentation under a calibrated load, where higher numerical values represent harder woods. Perupok scores a Monnin hardness rating of 1.7 at 12% moisture content, placing it in a moderately soft to medium-hard bracket. Mechanically, the mature timber demonstrates a crushing strength of 39 MPa (about 5,660 psi), a static bending strength (modulus of rupture) of 70 MPa (about 10,150 psi), and a modulus of elasticity of 15,380 MPa (about 2,231,000 psi). These mechanical figures demonstrate sufficient stiffness for long table spans when paired with rigid epoxy fills.
Shrinkage, Movement, and River Table Interface
Understanding wood movement is essential when locking lumber into rigid epoxy pours. Perupok possesses a total tangential shrinkage of 5.9% and a total radial shrinkage of 3.5%, yielding a tangential-to-radial shrinkage ratio (St/Sr) of 1.7. Its coefficient of volumetric shrinkage is 0.43% per 1% change in moisture content, with a fiber saturation point recorded at 30%.
An St/Sr ratio of 1.7 indicates moderate differential movement across the grain orientations. In a river table build, tangential live edges abutting cured epoxy will exert more movement across fluctuating ambient relative humidity than quartersawn surfaces. Proper moisture acclimation prior to casting is critical to keep shear stresses along the wood-resin bond line within manageable thresholds.
Drying Behavior and Working Characteristics
CIRAD rates the drying speed of Perupok as rapid to normal. Drying defects are generally low: the CIRAD sheet lists no risk or very slight risk of distortion, slight risk of checking, no known specific risk of collapse, and no known specific risk of casehardening. Suggested kiln programs operate within the 55 °C to 65 °C range (about 131 °F to 149 °F).
However, woodworkers must heed a critical shop note highlighted by CIRAD: Perupok is “very prone to splits.” While surface checking during standard drying is slight, the timber readily develops splits along grain boundaries during handling, drying, or processing. Cutting tools and saw blades experience normal blunting and require only ordinary steel or alloy steel tooling. Nailing and screwing properties are rated as good, though pre-boring near ends is recommended to avoid triggering the species’ splitting tendencies.
Natural Durability and Listed Uses
Perupok is strictly an interior timber. CIRAD classifies its heartwood as Durability Class 4 (poorly durable against xylophagous fungi) and Class S (susceptible) to both dry-wood borers and termites. Heartwood treatability is Class 2 (moderately permeable), and its natural durability ensures only Class 2 use conditions (inside or under cover, where dampness is possible). CIRAD lists primary end-uses including furniture and furniture components, interior joinery, interior panelling, moulding, seats, rolling shutters, sliced veneer, blockboard, and plywood veneers.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Lophopetalum javanum, Lophopetalum multinervium, Lophopetalum wightianum, Lophopetalum p.p. | |
| Colour / texture / grain | Yellow brown; texture fine; grain straight or interlocked; interlocked grain slight | |
| Specific gravity (12% MC) | 0.55 | about 34.3 lb/ft³; a 2-inch-thick slab weighs about 5.7 lb per sq ft |
| Monnin hardness (12% MC) | 1.7 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.9 % | green to oven-dry |
| Total radial shrinkage | 3.5 % | green to oven-dry |
| Ratio St/Sr | 1.7 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.43 % per % MC | volume change per 1% change in moisture content |
| Fibre saturation point | 30 % | |
| Thermal conductivity | 0.19 W/(m·K) | |
| Crushing strength (12% MC) | 39 MPa | about 5,660 psi |
| Static bending strength (12% MC) | 70 MPa | about 10,150 psi |
| Modulus of elasticity (12% MC) | 15,380 MPa | about 2,231,000 psi |
| Decay (fungi) resistance | Durability class 4 – poorly durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class S – susceptible (risk in all the wood) | |
| Heartwood treatability | Class 2 – moderately permeable | |
| Use class from natural durability | Class 2 – inside or under cover (dampness possible) | |
| Drying | rate rapid to normal; distortion: no risk or very 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 normal; saw teeth: ordinary or alloy steel; cutting tools: ordinary | |
| Nailing and screwing | Good | |
| 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).
Practical Pre-Pour Checklist for Perupok River Tables
- Inspect for Internal and End Splits: Carefully examine raw boards for hairline splits along the face and ends, as CIRAD explicitly identifies this species as very prone to splitting.
- Verify Target Moisture Content: Confirm that the slab is uniformly dried to interior equilibrium moisture content (typically within the range of 6% to 12% MC) before casting.
- Aspirate and Seal Porous Edges: Seal the live edges with a thin brush coat of epoxy to seal the fine pores and hairline checks prior to the main deep pour.
- Provide Tool Clearance: Machine edges using sharp ordinary or alloy steel blades, taking light passes to prevent split propagation at board corners.
- Plan for Interior Use Only: Restrict finished Perupok epoxy projects to dry indoor environments matching its Class 2 interior durability profile.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: According to the CIRAD Tropix datasheet, heartwood preservative treatment is mandatory against dry-wood borers and temporary humidification, but CIRAD explicitly advises that use of Perupok in permanent humidification is not recommended. (Source: CIRAD Tropix 7 technical sheet: Perupok.)