Common Name(s): Black walnut, American walnut
Scientific Name: Juglans nigra
Distribution: Eastern United States
Tree Size: 100-120 ft (30-37 m) tall,
2-3 ft (.6-1 m) trunk diameter
Average Dried Weight: 38 lbs/ft3 (610 kg/m3)
Specific Gravity (Basic, 12% MC): 0.51, 0.61
Janka Hardness: 1,010 lbf (4,490 N)
Modulus of Rupture: 14,600 lbf/in2 (100.7 MPa)
Elastic Modulus: 1,680,000 lbf/in2 (11.59 GPa)
Crushing Strength: 7,580 lbf/in2 (52.3 MPa)
Shrinkage: Radial: 5.5%, Tangential: 7.8%,
Volumetric: 12.8%, T/R Ratio: 1.4
Color/Appearance: Heartwood can range from a lighter pale brown to a dark chocolate brown with darker brown streaks. Color can sometimes have a grey, purple, or reddish cast. Sapwood is pale yellow-gray to nearly white. Figured grain patterns such as curl, crotch, and burl are also seen.
Grain/Texture: Grain is usually straight, but can be irregular. Has a medium texture and moderate natural luster.
Rot Resistance: Black walnut is rated as very durable in terms of decay resistance, though it is susceptible to insect attack.
Workability: Typically easy to work provided the grain is straight and regular. Planer tearout can sometimes be a problem when surfacing pieces with irregular or figured grain. Glues, stains, and finishes well (though walnut is rarely stained). Responds well to steam bending.
Allergies/Toxicity: Although severe reactions are quite uncommon, black walnut has been reported as a sensitizer. Usually most common reactions simply include eye and skin irritation. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.
Pricing/Availability: Very popular and widely available, though board widths can sometimes be narrow. Wastage can be high if sapwood is not accounted for in projects. Considered a premium domestic hardwood, prices are in the high range for a domestic species.
Sustainability: This wood species is not listed in the CITES Appendices, and is reported by the IUCN as being a species of least concern.
Common Uses: Furniture, cabinetry, gunstocks, interior paneling, veneer, turned items, and other small wooden objects and novelties.
Comments: It would be hard to overstate black walnut’s popularity among woodworkers in the United States. Its good working characteristics, coupled with its rich brown coloration puts the wood in a class by itself among temperate-zone hardwoods. To cap it off, the wood also has good dimensional stability, shock resistance, and strength properties.
In limited situations, black walnut can sometimes be considered as an alternative to ebony and other dark colored hardwoods.
Porosity: semi-ring-porous (sometimes closer to diffuse porous depending on growing conditions and age); growth rings generally discernible by gradual change in pore size from earlywood to latewood
Arrangement: solitary and radial multiples, sometimes forming a broken row in earlywood, with pore size grading down in latewood with overall diffuse distribution
Vessels: large to very large in earlywood, grading down to medium in latewood, few to very few; tyloses common
Parenchyma: diffuse-in-aggregates, banded (marginal), and sometimes reticulate (though most parenchyma tends to have very little contrast and can be quite hard to see even under magnification)
Rays: narrow to medium width, normal spacing; rays generally not visible without magnification
Lookalikes/Substitutes: The semi-ring-porous gradation in pore size from earlywood to latewood helps to separate black walnut from nearly all other unrelated imported walnut lookalikes, which tend to be diffuse porous—e.g., African walnut, New Guinea walnut, and Queensland walnut.
In mid-century and antique furniture, where the endgrain is not easily visible, black walnut is most commonly confused with Honduran mahogany. Although black walnut tends to be darker brown, both woods are variable in color and can have similar appearance when coloration is an intermediate golden brown. But on quartersawn sections, walnut will lack the ribbon patterning that’s usually seen in mahogany. And on flatsawn sections, the size of the pores can be closely examined for size gradation/variation (indicating walnut). Mahogany’s pores are of a much more uniform size, demonstrating its diffuse porous arrangement (which can be seen more clearly on the endgrain).
Notes: Within the Juglans genus, separation of individual species can be very difficult. Knowing the geographical source of the lumber is usually the best indicator, though the two most common commercial species, J. nigra and J. cinerea have an overlapping distribution in the eastern United States. While J. cinerea (butternut) tends to be lighter in both weight and color, the two can sometimes be confused if the color and weight are ambiguous. However, butternut trunks are are very often fluted, sometimes giving the growth rings in processed lumber a more faceted or polygonal appearance rather than perfectly curved.