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 Black Locust (Robinia pseudoacacia)
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Common Name(s): Black Locust, Robinia, False Acacia Scientific Name: Robinia pseudoacacia Distribution: Central-eastern United States (also widely naturalized in many temperate areas worldwide) Tree Size: 100 ft (30 m) tall, 3 ft (1 m) trunk diameter Average Dried Weight: 51 lbs/ft3 (825 kg/m3) Hardness: 1,700 lbf (7,560 N) Rupture Strength: 19,400 lbf/in2 (133,790 kPa) Elastic Strength: 2,050,000 lbf/in2 (14,140 MPa) Crushing Strength: 10,200 lbf/in2 (70.3 MPa) Shrinkage: Radial: 4.6%, Tangential: 7.2%, Volumetric: 10.2%, T/R Ratio: 1.6 |
Color/Appearance: Color can range from a pale greenish-yellow to a darker brown. Tends to darken to a russet brown with age. Can be confused with Osage Orange and Honey Locust in some instances.
Grain/Pore: Grain is usually straight, with a medium texture.
Endgrain: Ring-porous; large earlywood pores 2-3 pores wide, small latewood pores in clusters and tangential bands; tyloses extremely abundant; growth rings distinct; rays barely visible without lens; parenchyma vasicentric, aliform, and confluent.
Durability: Rated as very durable in regard to decay resistance, with good weathering characteristics. Frequently used as fence posts for its outdoor longevity.
Workability: Overall working characteristics for Black Locust are mixed: although the grain is usually straight, its high density and hardness can make it difficult to machine. Black Locust also has a moderate blunting effect on cutting edges. Responds very well to both lathe turning and steam bending; glues and finishes well.
Scent: There is no characteristic odor associated with this wood species.
Safety: Although severe reactions are quite uncommon, Black Locust has been reported to cause eye and skin irritation. Another (uncommon) side effect reported is nausea. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.
Price/Availability: Black Locust prices can vary depending on location, but prices should be moderate within its natural range. Those living in the eastern United States can expect prices to be comparable to White Oak. In other areas where the lumber has been imported, the prices can be much higher.
Comments: Black Locust is a very hard and strong wood, competing with Hickory (Carya genus) as the strongest and stiffest domestic timber: but with more stability and rot resistance.
Although it shares a similar common name with Honey Locust, the two aren’t in the same genus, (Robinia and Gleditsia, respectively). Black Locust tends to be slightly heavier, harder, and with more of a green or yellow tinge, while Honey Locust tends to have a warmer orange or red tint.
Some common uses for Black Locust include: fence posts, boatbuilding, flooring, furniture, mine timbers, railroad ties, turnery, and veneer.
None available.
Scans/Pictures: A special thanks to Steve Earis for providing the wood sample and turned photo of this wood species.
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Black Locust (sanded) |
 Black Locust (sealed) |
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 Black Locust (endgrain) |
 Black Locust (endgrain 10x) |
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 Black Locust: fluorescence (under blacklight) |
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June 10th, 2010 at 3:07 pm
This species grows well when planted on farmland on the southern BC coast, and is a local favourite for crooks, knees and ribs in traditional boatbuilding. It is dimensionally stable and extremely rot resistant, similar but harder/tougher than teak. I find that working and sanding the raw wood does not irritate eyes or skin as much as teak does, but it does irritate the nasal passages, and also causes something almost like a mild case of asthma – constriction in the bronchial tubes. I highly recommend wearing a particle filter mask when working with Black Locust.