Black Locust
Robinia pseudoacacia
Black Locust is one of the hardest and most durable domestic hardwoods available, rivaling many tropical species in rot resistance and longevity. This exceptionally strong wood features attractive golden to greenish-brown coloration and outstanding natural resistance to decay, insects, and ground contact. Once widely used for fence posts and railroad ties, Black Locust is now gaining popularity for decking, outdoor furniture, and sustainable building projects as a domestic alternative to imported tropical hardwoods.
Janka Hardness
1700 lbf
Very hard
Density
48 lbs/ft³
Dense
Shrinkage
Moderate (7.2% tangential, 4.6% radial)
Good stability
Appearance
Color: Golden yellow to greenish-brown heartwood that darkens to russet brown with age. Sapwood is pale yellow-white, clearly distinct.
Grain: Straight to slightly irregular grain with coarse texture. Attractive figure when quartersawn.
Key Characteristics
- •Extremely durable and rot resistant
- •One of hardest domestic woods
- •Outstanding ground-contact performance
- •Excellent strength-to-weight ratio
- •Natural insect resistance
- •Sustainable and fast-growing
Common Applications
Maintenance
Exceptional durability with minimal maintenance. Can be left unfinished in ground contact for decades. Oil annually to preserve color for above-ground applications.
Advantages
- +Exceptional natural rot resistance
- +Rivals tropical hardwoods for durability
- +Domestic and sustainably harvested
- +Suitable for ground contact without treatment
- +Very long service life (50+ years for posts)
- +Fast-growing and renewable
Considerations
- •Can be difficult to work due to hardness
- •Thorny tree makes harvesting challenging
- •Limited availability in wider boards
- •Color can vary between boards
- •May cause skin irritation
- •Prone to checking if not properly dried