Let’s take a look at African Walnut, also known as Congowood, Dibetou, Tigerwood, or Uganda Walnut. This hardwood is derived from the Lovoa Trichilioides tree, a monoecious, evergreen species indigenous to Central and Southern Africa’s tropical regions.
African Walnut Lumber
Characteristics of African Walnut
Despite it not being a true walnut (of the Juglans genus), it shares many of the basic characteristics. Here are some key characteristics of African Walnut lumber:
- 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.
- Odor: Black walnut has a faint, mild odor when being worked.
- 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
- Rays: narrow to medium width, normal spacing; rays generally not visible without magnification
African Walnut’s grains are typically straight or slightly interlocked - yielding good working properties - with a fine to medium, consistent texture and a fine natural luster. Finding figured pieces is not uncommon.
Workability and Durability
African Walnut offers good working properties, turning, gluing, and finishing well. Here's a closer look at its workability and durability:
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- 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.
- Rot Resistance: Black walnut is rated as very durable in terms of decay resistance, though it is susceptible to insect attack.
Common Uses
African Walnut is a versatile wood with a variety of applications. Its heartwood color can vary anywhere from a golden brown to a reddish brown, often with darker streaks and/or portions. Over time, its color will darken to deeper brown tones. The sapwood is narrow, grey to beige in color, and clearly demarcated from the heartwood.
Here are some of the common uses for African Walnut lumber:
- Furniture
- Cabinetry
- Gunstocks
- Interior paneling
- Veneer
- Turned items
- Small wooden objects and novelties
The principal use of Walnut Lumber is furniture, cabinetry, gunstocks, interior paneling, veneer, turned items, and other small wooden objects and novelties.
Sustainability
Making the ‘green’ choice is certainly a design priority. Historically, African hardwoods have been associated with unsustainable forestry and overexploitation. This is still a big concern, but progress has been made in recent years.
As part of UK and European Union timber regulations (UKTR and EUTR), due diligence has to be carried out to trace the source of any timber being imported. Next year, these regulations will become even more stringent, with the requirement for GPS locations for every felled tree.
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The key is to only buy your wood from a timber importer and merchant with a clear environmental commitment, who carry out all appropriate checks. You might also like to specify a wood certification scheme, like PEFC or FSC.
In terms of eco-friendliness, walnut is a great option. By choosing a sustainably-sourced domestic variety, materials spend less time in transit, reducing the carbon footprint. Moreover, harvests are overseen by tight US regulations, meaning tropical deforestation is not a concern. Its also worth taking into consideration that walnuts durability ensures a piece will last 50 or more years when designed by a quality craftsman, whereas a person could easily toss 10 cheap particle board pieces in the trash in the same amount of time.
Although not endangered, there are far fewer trees than before, so mindful companies like ours obtain the wood from sustainable sources; most often from states like Ohio, Indiana, and their neighbors.
Color Changes Over Time
Unlike cherry, maple, and oak (which all darken in color as they age), walnut wood will actually lighten slightly over time. Many things can change the natural color of walnut wood. For example, the elements will often darken light wood and lighten dark wood, so sun exposure over a period of years will typically cause walnut wood furniture to lighten.
While some will use stain on walnut wood, which will make it maintain the darker hue indefinitely, it is typically clear-coated or oiled. A clear coat doesn’t stop the color change altogether, but it can minimize it if maintenance is performed regularly. On the other hand, an oil-finished piece needs to be oiled regularly, which will give it richer hues over time.
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Some wood producers will also use steam in their drying process to try to even out the coloring between the heartwood and sapwood as well. This often brings out more grays in the piece, so its a practice our craftsmen like to avoid when selecting their lumber.
Comparison with Other Walnut Species
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).
Caring for Walnut Wood Furniture
The care of your furniture depends largely upon what type of wood finish is used to seal the wood. While all pieces benefit from regular dusting, its generally best to avoid commercial cleaners as they can sometimes leave residue on pieces with a lacquer finish or damage wax and oil finishes.
Pieces with an oil finish generally do best if a natural Danish linseed oil is applied at least once per year, though those in warmer climates may need to do this more often.
Grades and Availability
Walnut Lumber is available in 6 foot up to 14 foot in widths from 4 inches to 12 inches and wider. Lengths are anywhere from 6 feet to 16 feet although for shipping UPS requires all boards to be 8′ or less.
Walnut Lumber Characteristics Availability: Walnut Lumber is available in 6 foot up to 14 foot in widths from 4 inches to 12 inches and wider. Lengths are anywhere from 6 feet to 16 feet although for shipping UPS requires all boards to be 8′ or less.
Here's a table summarizing the available thicknesses:
| Thickness | Description |
|---|---|
| 4/4 | 1″ Rough, 25/32″ S2S&SL1E, S4S |
| 5/4 | 1-1/4″ Rough, 1″ S2S&SL1E, S4S |
| 6/4 | 1-1/2″ Rough, 1-1/4″ S2S&SL1E, S4S |
| 8/4 | 2″ Rough, 1-13/16″ S2S&SL1E, S4S |
