Black Locust (Robinia pseudoacacia)
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: 65-100 ft (20-30 m) tall, 2-3 ft (.6-1 m) trunk diameter

Average Dried Weight: 48 lbs/ft3 (770 kg/m3)

Specific Gravity (Basic, 12% MC): .66, .77

Janka Hardness: 1,700 lbf (7,560 N)

Modulus of Rupture: 19,400 lbf/in2 (133.8 MPa)

Elastic Modulus: 2,050,000 lbf/in2 (14.14 GPa)

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/Texture: 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; narrow to medium rays barely visible without lens, spacing normal; parenchyma vasicentric, lozenge, and confluent.

Rot Resistance: 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.

Odor: No characteristic odor.

Allergies/Toxicity: 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.

Pricing/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.

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: Fence posts, boatbuilding, flooring, furniture, mine timbers, railroad ties, turned objects, and veneer.

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.

Related Species:

None available.

Related Articles:

Scans/Pictures: A special thanks to Steve Earis for providing the wood sample of this wood species.

Black Locust (Robinia pseudoacacia)
Black Locust (sanded)
Black Locust (sealed)
Black Locust (sealed)
Black Locust (endgrain)
Black Locust (endgrain)
Black Locust (endgrain 10x)
Black Locust (endgrain 10x)
Black Locust: fluorescence (under blacklight)
Black Locust: fluorescence (under blacklight)
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Tim

Does Black Locust need to air dried before Kiln drying

ben

can’t do the camera But I did a wide plank bl. locust floor and the wood planks I “tanned” in the hot July Sun, the wood turns a great orange/brown and highlights the grain, but you have to be clever about warping. I did a pretty good job of it. can apply water mist covered by thin plastic overnight and the “U” warp flattens out. 5 days max for the color change in the sun. any more does not add to it.

Steve Dean

My plan is to make kitchen countertops of heartwood black locust 2 x 5’s (true measure) planks. The rough cut planks air-dried for 20 months, and then the planks were fine-milled for direct use. I’ve read that stainless steel screws are best to join the planks. But I’ve read conflicting advice on gluing black locust planks together. Also, what best to seal the finished product OR can I leave the planks unfinished? Can anyone with experience give me advice? My thanks in advance.

Brett

Steve, SS 305 for sure and our Robi Oil is specially made for BL.

zbeasley

Pure Tung Oil is a great food grade finish that i like to use on butcher blocks. Just ventilate well, takes a couple weeks for it to cure and air out but it isn’t a harsh chemical smell.

John W

A beautiful wood, for certain. A pain to work as well. Absolutely worth it though. I make stunning coasters from Black Locust after applying a Lichtenberg burn. The way it glows under UV light is captivating. I’m not 100% on the terminology but the coasters I’ve made are cut from stumps where a smaller tree has grown into a larger tree. I take off the smaller tree and then use that to saw into small slices. I saw someone me mention something about “oyster” and one shape absolutely looks like an oyster or clam shell. Another looks like a brain.… Read more »

ExRxIT

Black locust guitar back with nice figure and chatoyance, and it sounded great. Unfortunately it is rare to find pieces you can get guartersawn guitar backs from.

Steven Bryan

I have a Black Locust and a Northern Catalpa tree on the edge of my property. Both are 4’+ at the base. I live on the old Pennsylvania RR right of way in Indpls. These trees are probably 200 years old.

Brian

Wow. Those are dandies! I found a 3 footer yesterday. Happy tree spotting.
Brian

Matt Longenbaugh

Here in western WA, i see scattered black locust trees in right-of-ways typically 3 to 8+ inch dbh that grew from nearby stumps and naturally spread seeds. Similar to wisteria bushes, it is extremely invasive in sprouting from established plants. Can recommend riving to make tool handles, stool legs, outdoor furniture, and handrails. Epoxy glue appears to work best – not recommended for aliphatic (yellow) or white glues. Interlocked grain is difficult to plane evenly.

Gabriel Anaya

I have a huge Black locust I have named the “ locust monster “ here in Frederick Maryland, USA. It’s leaves are awe full to try to clean up since almost year round ( not winter ) they ha e a tendency of falling, and due to their small in nature size they get in the smallest or biggest cracks crevices, clog gutters, create ice damming, stain anything they land on that you don’t remove them from immediately, etc. it has 2 more locust monsters coming out of it and measured over 70 ft. Does anyone here know if I… Read more »

Richard Glabach

Hi – I live in Damascus MD and want to buy the black locust logs. Please contact me at 301-253-4087 or at rglabach@yahoo.com.

Russ Corbett

I recently got some dark brown almost black wood that the person who gave it to me identified as baked locust. He said the color came from the baking process that increased the woods resdistance to insects and rot.
Does anyone know where I can obtain more?

dan summerhill

Russ, the baking process is an issue. There are several companies doing it in the US and Europe but it is sketchy. It significantly weakens the lumber by carbonizing the sucrose. We tried this lumber several years ago in several species and distributed it for a year. We stopped because it does not live up to it’s claims.

Brett

This is correct, if you KD BL or bake it above 225 you actually destroy the cell structure of the wood and it destroys the rot resistance.

Mihai

In romania there are black locusts everywhere,in any city or garden and on every road.Its such an invasive specie that became so common until it made people here think its a romanian native tree.Its not cut for lumber ,even if its hard and looks almost like ebony and probably even beats somme of the ebonyes at darkness.The main purpose for what its planted here is for the bees,because it makes a verry clear almost like water honey thats expensive.Basically every beekeper here plants these trees all his life and somme even plant forests.In europe,romanian black locust honey its verry famous… Read more »

Fred

Almost a year ago I bought a guitar made by Hora (based in Romania). They make an ‘eco’ series of classic guitar that uses spruce (top), maple (technically, sycamore maple ..I think, for back/sides) and BL for fingerboard and bridge. All woods are solid, not laminates. It’s considered a low-budget mass production instrument (at least based on price) that uses the classic Torres design. All in all though, the combination of woods look, feel and sound great — sonically, it works. The choice to substitute BL instead of EIR is a brilliant choice IMHO. Most of the basic characteristics are… Read more »

Steve

My favorite wood for walking sticks and canes.

Andrew Wright

Does anyone know how long it will keep its fluorescence? Is it lost once dried?

Andrew Wright

Thanks. That does make it an interesting prospect for turning.

Vasco Chit

Hello every body,
Can anyone recommend me some suppliers of Robinia wood in Europe? I am looking quite big quantities of this wood.

Alan Drake

I am going to source mine from Arkansas for flooring in a new home in New Orleans. I could have put in a container to EU. My email is AlanSDrake at a gmail account.

Somika87

In Europe a good start would be Hungary, 22,5% of all forested area is robinia, that is ~460k ha of forest.
I’m positive that you’d find what you’re looking for, whatever the quantity.

David Breeze

One note of caution: With all its positive attributes you may be tempted to plant Black Locust on your property. Be aware that it is somewhere near the top of the scale for invasiveness! I sprouted 5 seeds a few years back and planted them in a corner of my lot. Three years later there were locust sprouts coming up in a garden 70 feet away from the little trees – and the trees had not borne seeds yet. But they had sent out finger-sized roots 100 feet long, seeking fertile ground and ready to create new trees from any… Read more »

Dan

I have to agree, we had two trees and cut them down and the roots sprouted literally hundreds of new trees all over our lawn and under our deck!

We cut the trees down 5 years ago and still have to dig up roots and trees.

Perry

I have 50 acres in central PA. Black Cherry, Red Maple, Mulberry, Alanthus, Black Walnut and Black Locust pop up like weeds everywhere. I spend several days each year clearing the seedlings from fields and fence rows. Black Locust over 12 inches in diameter has often started to hollow already. The trees may look solid, but they are brittle and tops break off making it dangerous for tree cutters. I do like the smell of the Black locust blossoms in the spring. Reminds me of orange blossoms.

jet

Black locust is a toxic plant due to the toxalbumin content, most animals can’t eat it without getting sick. I suspect that’s why it lasts so long outdoors without surface treatment, the toxins in the sap kill off mold, mildew, and many bugs. I see paper wasps on the lumber and where they’ve taken their bit of the nest off a cured board. I built a deck out of it a few years ago and it’s now a really nice shade of grey after a summer with plenty of sunlight. Every splinter I got while building that deck made my… Read more »

AZ

Jet: I’ve been thinking about trying black locust as a replacement for pressure treated when rebuilding my own deck. Where did you find dimensional black locust suitable for a deck? What difficulties did working with it present? And how has it weathered?

Matthew Niedbala

There’s a lot more. Like cedar it’s resistant to water because of specialized storage cells that keep moisture from entering. It also has it’s own type of flavonoid which is a strong antioxidant which keeps oxidation away. Many other things keep fungi mold and bacteria from degrading it. Bugs however can get into black locust although it’s a last resort.

JPVan

Grows like a weed — at a height of 25′ you have three 8′ sections to be quartered and the result is 12 fenceposts. Working with one other guy, and setting aside land and materials cost, we had a system where we were producing $192/hr in cash and carry inventory and could scarcely keep up with demand when we were 25% cheaper than an inferior product at nearby farm supply stores.

Benton Frisse

Anyone have any ideas on how this would do as a striking tool handle? Primarily an ax or hammer handle?

Andrew Aucoin

it is excellent.

Matthew Niedbala

Watch splitting as it dries. It’s bad about that. Dry slow.

Robfan

While cutting a large oak into firewood I lost my splitting wedge. I cut two wedges from a piece of black locust (we call it robinier here, after the king’s gardiner, Robin (hence it’s latin name Robinia Acacia) who brought it here from America in 1604) and split 2.5 cords of oak with them. They haven’t died yet. Miracle wood that should replace all resistent exotic woods. However, due to its toxins I would avoid using it for a kitchen counter. In my experience, ash is the best for counters as it leaves no taste that might alter food, followed… Read more »

Mike Sillett

I am planning on making a 10 – 12 ft. long chisel ( actually i will be attaching a chisel to one end ).

The purpose is to chisel off growths high up on a tree trunk. I will be hammering from the lower end – maybe with a wood maul – or using it above my head to continuously jab away .

I am considering white oak, black locust and dogwood however maybe there is another type of domestic wood more suitable?

Does anyone with more wood knowledge than me have any ideas, recommendations or suggestions?

Anna Sternfeldt

Nice to find this site. I am amazed by Black Locust having so many advantages. Being a hard wood being able to thrive in temperate climate will make it a candidate for replacing the need for rainforest trees which is great. And also having the asset of being a legume which reduces the need for fertilizer, and this is just a few things… I have put some info together myself on Black Locust that may complement the interesting info on this site: https://hub.me/aeHwO

Alan Drake

Your locust link is dead.

Robin

When finding a black locust tree, it is recognizable from its coarse bark, it’s leaf pattern and its white flowers although there semm to be some new yellow flower cultivars such as Robinia pseudoacacia spp “Frisia” , resembling closely Laburnum anagyroides trees who are also Fabaceae and bear similar flowers and grow in the same regions, same climate. Laburnum trees have (unlike Robinia)a smooth and thin bark, and the leaves are alternated differently, but the wood is pretty similar, once expose to light, the creamy yellow Black Locust will resemble the initially honey light golden brown Laburnum , only one… Read more »

michael

This wood is very hard and i think quite a beautiful wood. Contrary to the description above, it has a very peculiar smell that is at first agreeable but soon becomes a bit too pungent /disagreeable. Over the course of a day of milling i realized the i was developing a sensitivity ( allergy) to the wood. I got a low grade nausea and a head ache. The next day i tried milling the wood without a respirator and soon found the headache coming on. Years ago making a deck out of western cedar I had a similar reaction. It… Read more »

Randy Gage

Iworked three days with western Cedar and a week later was hospitallized with pnumonnia. Go figure.

Arron

This is an amazing web site and it’s sad I just came across it. To add to Michael’s and Randy’s comments, I grew up with black locust in the Colorado front range and we used it for all sorts of things. I love the smell of it. I recently worked with a piece, a lot of filing and sanding. Had my wife smell it and watched her turn green. Mind you, this was just the wood and not the filings or shavings. My son, liked the smell with no reaction. Too much cedar gives me a headache too.

david cullen

I had four acacia trees in my yard cut down and sawn on the property. The wood is extremely hard and makes exceptionally fine wood for furniture. The wood takes stain well and once the moisture level gets down to 6% it machinabilty is excellent.The biggest problem is drying the wood to prevent warpage. I am now in the process of having two trunks that were cut down three years ago sawn into boards. When this is done I will know how the warpage works out. Once the warped boards are cut they remain stable and I have made several… Read more »

David Shipway

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.