Working with Pyinma (Lagerstroemia p.p.) in Epoxy Tabletops
Pyinma is an Asian-Oceanian hardwood belonging to the botanical grouping Lagerstroemia p.p. In fine furniture, it has long served in cabinetwork, flooring, and interior joinery. Technical data published by CIRAD Tropix provides builders with precise physical, mechanical, and drying characteristics for incorporating this timber into resin and wood table builds.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Lagerstroemia p.p. | |
| Colour / texture / grain | Light brown; texture medium; grain straight; interlocked grain absent | |
| Specific gravity (12% MC) | 0.70 | about 43.7 lb/ft³; a 2-inch-thick slab weighs about 7.3 lb per sq ft |
| Monnin hardness (12% MC) | 4.7 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 6.8 % | green to oven-dry |
| Total radial shrinkage | 4.2 % | green to oven-dry |
| Ratio St/Sr | 1.6 | 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 | 26 % | |
| Thermal conductivity | 0.23 W/(m·K) | |
| Crushing strength (12% MC) | 63 MPa | about 9,140 psi |
| Static bending strength (12% MC) | 116 MPa | about 16,820 psi |
| Modulus of elasticity (12% MC) | 15,690 MPa | about 2,276,000 psi |
| Decay (fungi) resistance | Durability class 3 – moderately durable | |
| Termite resistance | Class D – durable | |
| Dry-wood borer resistance | Class S – susceptible (risk in all the wood) | |
| Heartwood treatability | Class 3 – poorly permeable | |
| Use class from natural durability | Class 2 – inside or under cover (dampness possible) | |
| Drying | rate normal to slow; distortion: slight risk; checking: slight risk; collapse: no known specific risk; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–65 °C | about 127–149 °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).
What does Pyinma wood look like, and how is the grain structured?
Pyinma heartwood is light brown, occasionally presenting pink or grey shades. Its sapwood measures from 6 to 10 cm in thickness and is not clearly demarcated from the heartwood. The wood features a medium texture and a predominantly straight grain with interlocked grain completely absent. In certain boards, the grain can be wavy, providing subtle figure across wide tabletops.
What slab widths are possible from Pyinma logs?
According to CIRAD Tropix, Pyinma logs generally range from 60 to 100 cm in diameter. This diameter provides ample width for wide planks, bookmatched sets, and live-edge slabs suited for epoxy river designs. However, CIRAD logs data notes important risks of logs splitting, meaning raw slabs should be inspected carefully for longitudinal checks along the heartwood before planning table layouts.
How heavy and hard is Pyinma?
At 12% moisture content, Pyinma has an average specific gravity of 0.70. This equates to an air-dry density of about 43.7 lb/ft³, meaning a 2-inch-thick tabletop slab weighs approximately 7.3 lb per square foot. In terms of surface resistance, Pyinma rates at 4.7 on the Monnin hardness scale. Monnin hardness is a French standardized test where higher numbers reflect harder wood, distinct from the Janka scale. A rating of 4.7 indicates solid resistance against daily tabletop indentation without making the timber overly difficult to work.
How stable is Pyinma alongside an epoxy river?
Stability is critical when locking solid timber against rigid epoxy resin. Pyinma shows a total tangential shrinkage of 6.8% and a total radial shrinkage of 4.2%, resulting in a tangential-to-radial shrinkage ratio (St/Sr) of 1.6. A ratio close to 1 indicates a lower tendency toward cupping. Its coefficient of volumetric shrinkage is 0.46% per 1% change in moisture content, with a fibre saturation point of 26%. While overall distortion and checking risks are rated as slight, CIRAD notes risks of cracks in large boards. Table builders should ensure lumber is properly equalized to indoor equilibrium moisture content before pouring resin.
What drying risks should builders watch for?
Pyinma dries at a normal to slow rate. CIRAD identifies only a slight risk of checking and a slight risk of distortion, with no known specific risk of collapse or casehardening. The primary drying challenge lies in the tendency for cracks in large boards and splitting in unprocessed logs. CIRAD’s suggested kiln drying schedules manage these risks by keeping drying temperatures between 53 and 65 °C (about 127 to 149 °F).
How easily does Pyinma machine, plane, and fasten?
Pyinma performs cleanly in the shop with standard equipment. Its blunting effect on tools is normal, allowing woodworkers to cut and shape parts using ordinary cutting tools and ordinary or alloy steel sawteeth. However, where wavy grain is present, CIRAD notes that planing may become problematic and result in fuzzy surfaces, requiring sharp tooling and careful sanding. Mechanical assembly is dependable, with nailing and screwing rated as good.
What is Pyinma’s natural durability and CITES status?
Pyinma is classified as Durability class 3 (moderately durable) against wood-decaying fungi and Class D (durable) against termites. However, it is rated Class S (susceptible) to dry-wood borers throughout all the wood. Because of these factors, its natural durability places it in Use Class 2 (interior or under cover where dampness is possible), and permanent humidification is not recommended. For commercial sourcing and legality, Pyinma is not listed in the CITES Appendices under the Washington Convention 2025.
Sources
Published October 31, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: CIRAD Tropix rates Pyinma heartwood treatability as Class 3 – poorly permeable, meaning preservative liquids do not readily penetrate deep into the grain; for epoxy river table builds, ensure edge sealing relies on mechanical bonding rather than deep chemical saturation. (Source: CIRAD Tropix 7 technical sheet: Pyinma.)