Black Locust
Robinia pseudacacia • Hardwood
Grain Pattern
Straight to slightly interlocked grain with a medium to coarse texture. In the underlying wood, it often shows prominent earlywood pores (ring-porous).
Color Description
Bark is deeply furrowed and dark grayish-brown. Heartwood ranges from pale greenish-yellow to dark brown, while sapwood is thin and yellowish-white. It turns russet-brown with age and high UV exposure.
Hardness Rating
1700 lbf (Hard)
Durability Rating
Very Durable. Exceptional resistance to rot and decay; widely considered one of the most decay-resistant woods in North America.
Common Uses
Fence posts, railroad ties, heavy exterior construction, boat building, tool handles, tree nails (trunnels), and outdoor furniture.
Geographic Origin
Native to the Appalachian Mountains and the Ozark Plateau of North America; widely naturalized throughout North America, Europe, and parts of Asia.
Market Value & Sustainability
Estimated Market Value
$4.00 to $8.00 per board foot depending on availability and quality.
Wood Age Estimate
The thick, deeply fissured bark suggests a mature tree, likely 40-70 years old for a trunk of this size.
Sustainability Status
Not listed in CITES or the IUCN Red List; highly sustainable and considered invasive in some regions due to fast growth and nitrogen-fixing ability.
Workability
Difficult to work due to its extreme hardness and high density. It can dull cutting edges quickly. It glues well but is prone to splitting when nailed or screwed without pre-drilling.
Notable Features
Heartwood fluoresces under UV light; seeds and bark are toxic if ingested; known for excellent firewood due to high BTU content and ability to burn even when wet.
Finish Recommendations
Oil-based finishes or exterior-grade sealers are recommended to preserve the natural color, though it can be left unfinished to weather to a silver-gray.
Identification Confidence
High; the combination of deeply furrowed, interlacing bark ridges and the yellowish hue of the exposed inner wood is characteristic of mature Robinia pseudacacia.