Using Peruvian Walnut in Custom Wood and Epoxy Tabletops
Peruvian Walnut refers to several Latin American species of the genus Juglans, notably Juglans australis, Juglans boliviana, Juglans neotropica, and related species. Originating from subtropical and temperate regions across Central and South America—including Argentina, Colombia, Ecuador, Mexico, Peru, and Venezuela—this timber offers the classic, elegant appearance associated with walnut hardwoods. When designing an epoxy river table or solid wood-and-resin surface, understanding its physical movement, density, and working properties is essential for a reliable, long-lasting build.
The technical data summarized below is sourced directly from the CIRAD Tropix research sheet on Peruvian Walnut.
| Property | CIRAD Tropix value | What it means / US units |
|---|---|---|
| Botanical name(s) | Juglans australis, Juglans boliviana, Juglans neotropica, Juglans p.p. | |
| Colour / texture / grain | Dark brown; texture medium; grain straight; interlocked grain absent | |
| Specific gravity (12% MC) | 0.61 | about 38.1 lb/ft³; a 2-inch-thick slab weighs about 6.3 lb per sq ft |
| Monnin hardness (12% MC) | 3.5 | French hardness scale; higher = harder (not a Janka value) |
| Total tangential shrinkage | 5.2 % | green to oven-dry |
| Total radial shrinkage | 2.7 % | green to oven-dry |
| Ratio St/Sr | 1.9 | closer to 1 = less cupping tendency |
| Coefficient of volumetric shrinkage | 0.40 % per % MC | volume change per 1% change in moisture content |
| Thermal conductivity | 0.21 W/(m·K) | |
| Crushing strength (12% MC) | 36 MPa | about 5,220 psi |
| Static bending strength (12% MC) | 57 MPa | about 8,270 psi |
| Modulus of elasticity (12% MC) | 8,720 MPa | about 1,265,000 psi |
| Decay (fungi) resistance | Durability class 3 – moderately durable | |
| Termite resistance | Class S – susceptible | |
| Dry-wood borer resistance | Class D – durable (sapwood demarcated, risk limited | |
| Heartwood treatability | Class 2-3 – poorly to moderately 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: yes; casehardening: no known specific risk | |
| Suggested kiln program temperatures | 53–62 °C | about 127–144 °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). Notes. In the subtropical and temperate regions of Central and South America. |
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 Peruvian Walnut look like, and how is its grain structured?
Peruvian Walnut features a dark brown color reference. The sapwood is grey-white, measuring from 2 to 5 cm in thickness, and is clearly demarcated from the heartwood. The heartwood is described as dark grey-brown with a pink tinge, occasionally exhibiting dark brown or reddish-brown veins that are typically less pronounced than those found in European and Asian Juglans species. Its texture is medium, its grain is straight, and interlocked grain is entirely absent. In river table construction, the distinct boundary between the pale sapwood and rich dark brown heartwood provides an attractive natural transition along live edges casting into resin.
How heavy and hard is Peruvian Walnut?
At 12% moisture content, Peruvian Walnut has a specific gravity of 0.61, which corresponds to a density of about 38.1 lb/ft³. For builders planning a typical 2-inch-thick slab tabletop, the lumber weighs roughly 6.3 lb per square foot before accounting for epoxy volume.
In terms of hardness, CIRAD Tropix records a Monnin hardness of 3.5. The Monnin hardness test is a standard French wood scale evaluated on a cylindrical indentation; higher values indicate a harder surface. (Note that Monnin hardness is distinct from the North American Janka test and cannot be directly converted.) Mechanically, Peruvian Walnut demonstrates a crushing strength of 36 MPa (about 5,220 psi), static bending strength of 57 MPa (about 8,270 psi), and a modulus of elasticity of 8,720 MPa (about 1,265,000 psi).
How does Peruvian Walnut shrink, and what does this mean for an epoxy river?
Managing dimensional movement is critical in resin woodworking because epoxy does not shrink or expand at the same rate as natural wood. Peruvian Walnut exhibits relatively modest total shrinkage from green to oven-dry:
- Total tangential shrinkage: 5.2%
- Total radial shrinkage: 2.7%
- Tangential to radial ratio (St/Sr): 1.9
- Coefficient of volumetric shrinkage: 0.40% per 1% change in moisture content
An St/Sr ratio of 1.9 indicates a moderate difference between tangential and radial movement, suggesting manageable cupping tendencies during climate shifts. The low coefficient of volumetric shrinkage (0.40%) helps minimize joint stress along the epoxy-wood boundary, provided the lumber is brought to an appropriate interior equilibrium moisture content before casting.
What are the risks when drying Peruvian Walnut slabs?
The drying rate for Peruvian Walnut is classed as normal to slow, while veneers are specifically noted to dry slowly. According to CIRAD, the risk of distortion is slight, checking carries a slight risk, and casehardening presents no known specific risk. However, there is a known risk of collapse. CIRAD suggests a kiln schedule with temperatures progressing from 50 °C up to 62 °C (roughly 127 °F to 144 °F). Because thick slabs intended for furniture are particularly vulnerable to internal drying collapse, slow, controlled moisture removal is necessary prior to flattening and casting.
How easily does Peruvian Walnut machine and assemble?
Working Peruvian Walnut in the shop is straightforward:
- Tool blunting: Normal blunting effect on cutters.
- Tool requirements: Standard cutting tools and ordinary or alloy steel saw teeth perform satisfactorily.
- Fasteners: Nailing and screwing properties are rated as good.
- Shaping: The wood is noted for good performance in peeling and slicing.
These working traits make it simple to mill clean edges, carve live edges, and rout channels for structural hardware or C-channels underneath the tabletop.
What is the durability and CITES status of Peruvian Walnut?
Peruvian Walnut heartwood is rated as Durability Class 3 (moderately durable) against wood-decay fungi. It is rated Class D (durable) against xylophagous dry-wood borers, with risks limited to its demarcated sapwood, but Class S (susceptible) against termites. Heartwood treatability is Class 2–3 (poorly to moderately permeable). CIRAD designates its natural durability for Class 2 use: inside or under cover where dampness is possible. If exposed to permanent humidification, its use is not recommended.
Regarding trade regulations, Peruvian Walnut is not listed in the CITES Appendices according to the Washington Convention (2025). Its recognized industrial end-uses include cabinetwork and high-class furniture, interior joinery, turned goods, wood-ware, sculpture, and veneers—sharing very similar applications to temperate walnuts.
Sources
Published October 30, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: Because CIRAD Tropix warns that Peruvian Walnut has a documented risk of wood collapse during drying, builders purchasing live-edge slabs should carefully inspect boards for internal washboarding or cellular collapse before pouring deep epoxy sections. (Source: CIRAD Tropix 7 technical sheet: Peruvian Walnut.)