Black locust uses
It is the hardest commercial species in the U.S. That certainly means hard to saw, glue, machine, etc.
The main use today for black locust is... xylophone keys!
If used for firewood, it is exciting--the moisture in the wood is converted to steam during heating, but cannot escape. So all of a sudden, "POW!" and then sparks fly all over.
Gene Wengert, forum technical advisor
Here on the east coast black locust is used in boat building. I know of some people who have built beautiful furniture with it. We have two floors in our house made with it and I understand it makes beautiful turnings.
It seems to me that the perfect use for the low grade stuff is landscape timbers. Although heavy and hard, I think folks who are concerned about contamination from treated timbers would love to use it and pay a premium for it. I know I would. There's no way I'm going to use treated SYP or railroad ties around my vegetable garden. I have used northern white cedar but was disappointed that it lasted only 15 or 16 years. I would expect black locust would last 30 or 40? As a furniture maker who has used some locust, I would say the market for furniture wood is very limited. It is ugly to work with. Maybe it would be appropriate for garden furniture, though.
Black locust is very rot resistant. If moisture content is carefully controlled and the drying process slowed down, cracking is minimized.
Black locust has great structural strength and longevity. A lot of these trees were planted at the time of the California Gold Rush and used in mines to shore up the shafts. I have seen the lumber used all over the gold country for support timbers in old barns and in homes and also for flooring, stairs, mantles, etc.
I have a lot of black locust on my farm, which was planted by the original settlers. Black locust had the highest decay resistance of any local wood. In Europe it was highly valued and used extensively in the out door trim on houses. The wood is large grained with contrasting areas of green and yellow. Itís an extremely dense wood with a high BTU rating.
The trees I have tend to be gnarly and the larger trees decayed in the middle. It would be very difficult to get much lumber out of a tree.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
Not only is it tough (second only to osage orange as the toughest native wood) and resistant to moisture (much better than white oak) and rot (way batter than cedar), it is gorgeous! If you haven't seen it, picture the grain of oak and color it with gold and add a glow that shifts in the light.
Black locust is tougher than hickory, which is tougher than hard maple, which is tougher than oak. I have gotten it for only slightly more than the price of oak.
I only wish there was a supply of the lumber in my area. I'd make everything out of it. It has a very low rate of expansion and contraction, making it very stable for furniture and woodwork (interior or exterior).
Hard to work? Well, it's not balsa. Whaddaya expect when it's practically the most durable and stable wood available? Use sharper tools.
Comment from contributor B:
My parents have several dozen of these trees on their property. As a child I marveled at the coarse bark and the tall, lanky stature of these wonderful trees. After a bad ice storm toppled a few, my father cut all but one for firewood (the rest cracked and split as they came down). He dragged it to his sawmill across the road in the spring and sawed some dimensional lumber from it and placed the lumber in his basement. That was 15 years ago. A few months ago I nabbed a few boards and made a picture frame with an 8x10 photo of his mill inside. The colors that came out in that wood after a semi-gloss varathane was applied were amazing. The green and yellow hues were beautiful. The wood was a bit boxy when ripped on the table saw and it planed up nice with my 15" Makita floor planer. The finished product was better than I could imagine. If anyone has any of these, keep them standing; take deadwood or storm knockdowns. I have taken a few sprigs from the ground (they seem to spread like weeds!) and planted them at my house some 65 miles away and they are growing great. I have not seen these trees elsewhere in Nova Scotia and have no idea where they came from.
Comment from contributor C:
Posts made of locust wood are good for grapevine supports in vineyards. Locust wood lasts longer than pressure treated wood, and it does not leak harmful chemicals into the soil as pressure treated wood does, such as arsenic, which can be absorbed by the plant and therefore into the fruit. Vineyard posts are usually 8 feet long and about 4.5 inches in diameter. In a vineyard, 1.5 to 2 feet of the post is put into the ground, depending on the soil, and two to three wires are run between the posts on which the grapevine is tied. Locust can also be used for fence posts. Some use a waterseal to help it resist rot, and others use roofing tar on the part being put into the ground.
Comment from contributor D:
An article from 2002 in the Wooden Boat magazine discussed the attributes of black locust wood. There were a number of woods listed as desireable in the construction of wooden boats, including white oak, but none more desirable than black locust. Not only is the wood strong and durable, but less prone to wood rot and easily formed in the making of ribs. An excellent choice for those taking on a boat restoration project, or even a more aggressive new boat construction project.
Comment from contriutor G:
As a bandmill sawyer, last year I started sawing black locust, and what a surprise, it saws just as easy as cherry, and the grain and color is out of this world. I sawed a couple hundred board feet the other day to use as a floor for a kiln, due to the moisture resistance. It's the most under-rated lumber out there.
Comment from contributor R:
I had a project recently involving a wood that needed to be yellow but dark, like osage orange patina, for the handle of a fishing net. I made it out of osage. About two weeks later I was wandering in the back room of a wood supplier and found a piece that glowed with a golden magic I've only seen in lightly flamed bamboo. The small grains are light and the meat is a brassy golden color. It was black locust. I bought enough to do an experiment. Wow - you should see it in the sunlight. It's pretty hard, so sharpen those blades. Sands like a dream and polishes well. My supplier can't sell it, so I'm getting it for the price of pine!
Comment from contributor M:
I am a furniture maker in Central Illinois and my favorite sawmill had a few hundred board feet of perfectly straight and clear locust, which I bought. I made wonderful furniture! It is hard, but not really worse than hickory or oak. It planes fine if done at 64th or 32nd inch - even the wide boards. It is really beautiful. The grain is much like quilted maple and very colorful. If you have red oak that has been stained with standard golden oak stain, this looks much the same, but brighter. That is with no stain, just oiled the finished with polyurthane or lacquer. This is great wood for furniture and I can not understand why more people do not use it.
Comment from contributor V:
Get a black light and check, if you're uncertain about the species. Robinia P. is flourescent, and this may explain the luminous character others have noted. I agree it is our most under-appreciated lumber; and a crying shame that is.
Comment from contributor K:
Black locust is the best wood grown in North American, in my opinion. The general public is ignorant of this fact, though, which is good since that holds down lumber prices.
It's great for furniture, ideal for boat building and decks. It's also great for fenceposts, but that's a waste of a wood that is our best wood. It's a native exotic.
It is native to the Eastern USA, but was brought to CA by goldminers to grow for minining timbers. The railroads also planted it because it makes excellent railroad timbers for bridges and railroad ties.
Black locust can last well in excess of 70 years in the ground without painting or chemical treatment. It's very strong, shock resistant, stable (doesn't shrink or swell much), durable (rot resistant), looks great (in part due to fluorescent grain. It's somewhat hard to work, but not too bad, considering it's very hard. It's easy to glue. Unlike other very hard woods, black locust nails reasonably well. It is also a fairly smooth wood.
To get better physical properties than black locust, you have to look at ebony or some other expensive, exotic import. You can basically think of black locust as hickory that is more rot resistant and more stable when humidity changes. It looks similar to red and white oak, except is better looking due to greater smoothness and fluorescent grain.
It's considered a pest by some Western environmentalists because it's an aggressive tree that kills the Western native trees and plants in a wide area around it. However, that was a very useful quality to pioneer farmers who worked hard to clear fields. The easy way to keep a field cleared of brush, alder, other trees, and weeds is to plant some black locust. Black locust only allows grass to grow in its field. Nothing else. That's a convienent way to keep a field cleared without manual weeding or spraying weed killers.
Black locust is mostly dead in Oregon now due to a beetle attack. Black locust is mostly ignored in CA and WA. Though native to the Eastern USA, it's spread all over the Western USA and parts of the Southern Midwest and Europe. It is appreciated by environmentalists in those places because it is an easy, quick way to reforest strip mined areas and logged out areas. Although it prefers good soil and lots of sun, it can grown in bad soil (mine spoils) and cloudy and cold climates too. It has spread all over Canada over the last 250 years.
It was imported to France in the 1600s. The French recognized awesome shipbuilding wood when the saw it. They also used it for medicinal properties (seeds) and cooking (flowers). The seeds have also been used in Europe as a coffee substitute. The English importanted it to England hundreds of years ago where it still grows.
It has spread all over Western and especially Eastern Europe. The Europeans appreciate the black locust for it's supposed medicinal properties (seeds are laxative) and for the quality of its wood. The biggest attraction is that it is an aggressive tree that self-cultivates and spreads without any human effort needed. The black locust is reforesting much of the logged out areas of Europe that have been logged out for centuries. It's also a renewable resource for them since it's so easy to regrow. It's such an aggressive, persistant tree that it continually replants itself. Black locust is the national tree of Hungary and the basis of their forestry industry.
It makes great fence posts, but it's a far superior wood to white oak, hickory, hard maple, walnut, or cherry for furniture and boat building. Using black locust for fence posts is not the highest or best use of this wood. Black locust fence posts last well over 70 years without needing any chemical treatment.
I found a supplier of it who sells it for a bit less than white oak. I'd like to build a house and use it for the hardwood floor and desk. It would probably make great siding and roofing, too. Since it lasts 70+ years in the ground, it ought to last hundreds of years as siding or roofing. It's supposed to nail reasonably well.
Comment from contributor W:
Black locust is an awesome wood. It's most common use that I know of is wood boat building on the east coast of the USA - yachts, sailboats, etc. Black locust and osage orange are the finest woods that grow in the USA. I base this on their physical properties.
These are both native exotics. Exotic because they aren't widely used or known. The physical properties of black locust are nearly identical to purpleheart. The physical properties of osage orange are nearly identical to santos mahogany (not mahogany). The properties of black locust and osage orange are similar to hickory, except that hickory isn't very stable (shrinks and swells a lot with moisture changes and can rot easily if used outdoors). Both black locust and osage orange have the same good properties as hickory without its bad properties. Black locust and osage orange are stable and resistant to rot, mildew, germs, and bugs.
Don't whine about hardwoods being hard to work. What would you expect? If you want an easy-to-work wood, use a softwood, but expect dents and dings in the furniture or whatever you make from it. Hardwoods are tough, so they resist dents and dings. Therefore they also resist tools when working the wood. Use sharper tools. Use carbide tipped tools whenever possible.
Comment from contributor J:
While black locust has many incredible uses, it also has qualities that should be taken into account before anyone rushes out to plant it. For example, it is toxic to grazing animals and for that reason is maybe not the best way to clear a field. Goats might be fine with it; I don't know and don't have any experience with goats. My other animals will graze around most other plants that are supposedly toxic. Seems the animals are wise enough to eat just enough of whatever they might need for medicinal use and to avoid excess. Horses especially are extremely sensitive. One mouthful of yew can kill a horse before it finishes chewing. Cows might be wise enough to leave it alone. Ponies are generally pretty tough but will avoid most toxic plants. Goats might tolerate it, but again, that is something to look into.
It is also highly invasive, and while a controlled stand might be something very useful, it is good to remember that the stand will take over everything else if left untended.
Years ago a friend who does permaculture design recommended using existing stands for whatever I needed, but never to plant it. It regenerates itself quickly.
It may also be toxic to children, who love things that look like beans. Like poison ivy, the levels of toxins may vary at different times of the year and in different parts of the plant.
Be careful; don't plant it unless you can also be sure of removal if necessary.
Comment from contributor S:
Some have mentioned that black locust is very difficult to work with due to its density and hardness characteristics, while others have dismissed such concerns by saying to use sharper tools. As one who has worked with black locust, there are two types of black locust - those that are "long-cured" and those that are "green-cured."
Green-cured black locust, or fresh cut, is not terribly difficult to work with as the wood gives way to sharp implements and is fairly easily worked. Long, or "weather-cured" locust, locust that has been slow cured by age often in areas exposed to weather, is very hard and very difficult to work. In fact, if you try to cut an old locust fence post with a chain saw, a six-inch log will dull a brand-new chain, and forget about hand-planing. It's almost impossible to even drive a stout spike into a well-cured log unless you use very hard (and brittle) masonry nails. Everything else will pierce only about an inch and then bend. If you intend to work with black locust, make sure it hasnít been too-well cured. If it has, you'll only make much progress with power planers, high-grade saws and high-pressure nail-guns.
Comment from contributor E:
We got a lot of black locust logs in a while ago and have tried using the lumber for many things. It is rather tough to get any grade lumber from these trees, due to their typical gnarly growth and large cavities in the trees. The good lumber that you do get can be used to make nearly anything that is ok to be heavy, provided that you have sharp tools and some patience. The grain is very open and some of the more exotic whorls can be splintery. Where the grain is straight, it is extremely strong and can be cut paper-thin without splintering if your saw is sharp. It can be sensitive to vibration (brittle) if the grain is not continuous and parallel to the force acting on it, such as in a pittman arm. It shrinks very little and can be used for framing with minimal drying time. In fact, it becomes very hard to nail, even with a framing gun, when fully dry.
For use as flooring, trim, or projects it will need to be fully dry. With a good flooring stapler, you can nail the flooring down, but plan on drilling trim or projects before nailing. The wood that isn't good enough to be used visibly can be used for framing in high moisture environments, such as pool rooms, kilns or saunas. Otherwise, it is good for pallet stock or various small items. Below is a list of things we have used it for and the degree of success we achieved.
2x4, 2x6, and 2x8 framing timbers - excellent if you use decent lumber and don't wait too long.
Tongue and groove flooring - we put it down too soon and it shrunk. It is very hard and does the job, if you like yellow/green floors.
Exterior log posts and rails (8" plus diameter) Ė it has worked well so far. Very sturdy, no rot so far (only 3 years) and decent appearance with proper log selection. The stain we used didn't stick very well. It seems to have to do with the oils in the wood.
Bed frame struts - excellent, very sturdy and effective.
Three mowing machine pittman arms - fair. The first two broke because the grain was so uneven. The third one is still holding. Had we selected a piece with continuous grain from end to end (hard to find) it would probably have worked better.
Wheelbarrow handles - excellent. They were a bit hard to turn due to the hardness and open grain. It tends to grab the tool a bit, particularly on long work pieces like wheelbarrow handles. They are very strong (it's a large wheelbarrow and I've been using it a lot) and should last a long time.
Comment from contributor Y:
I have about 20 cords of black locust logs from a land clearing job we did last summer. It's a wonderful species for firewood Ė it burns hot and long if properly seasoned. It's also very rot resistant and commonly used for fence posts and exterior construction on farms. It's a fast growing pioneer tree here in the northeast - meaning it's one of the first species to appear in fields left fallow. It will seed itself in these old pastures and grow in fairly dense stands that are very straight and tall (sometimes over 100 feet).
The downside to this tree is that it's not the best choice for a yard. Its shallow surface roots make it prone to uprooting under certain weather conditions. Overall it's a very valuable wood with many uses and one of my personal favorites for firewood. Additionally, its rapid growth rate makes it a renewable resource - something we all need a bit more of!
Comment from contributor S:
I live on Long Island near the abandoned Kings Park Psychiatric Hospital. The hospital itself was established pre-1890, and the grounds (400+ acres) were apparently planted with many Black Locust trees, many of them now over 75-80 feet in height. Some of the older ones were cut down by N.Y. State in its infinite wisdom, and I was able to take out about a cord and a half of Locust as firewood.
Let me tell you, once properly split and dried, that wood is among the best I have ever burned in my heatilator-equipped fireplace. It burns slowly, and very hot. The key mechanism here is to make sure it is properly stacked and dried; this will keep spitting during burning to a low level. While splitting the wood one can't help but notice a beautiful gold-green sheen to the heavy, straight veined splits. The wood is as hard as any I've ever worked with, and I must agree with the wood-working individual above who states that it is of the highest quality!
Comment from contributor N:
I've had a number of large black locust trees taken down in the past due to age and potential property damage. I saved a number of large logs using them for landscape timbers - 10 years later they are still hard as a rock even with soil piled up against them. I am about to have more taken down - again due to potential risk of house damage. Two of them are roughly 3 feet in diameter - approximately 120 ft high.
After reading your posts the original plan to let the tree crew haul it away will change to having it band sawed into boards by a local guy with a portable mill. I could use some new decking and it sounds like the way to go! Thanks all for your comments - and I agree with the burning of it. Once itís dry it gets the wood stove hotter than any other wood species.
Comment from contributor F:
I have known of locust for some time as our local best choice for timber framing pegs. Much of my work of late has been barn repair for the NYS barn grant program. Being a historic preservation program, no pressure treated wood is allowed. So I had to secure a steady supply of timber for my various projects. Since then I've used it for many projects including pegs, fence posts, mud sills, scaffold planks (short), bark for mulch (where I want nothing to grow), and I just completed a corral of spilt rails.
On a job a couple years ago I found an old split rail in the dirt on the dark side of the building. I picked it up and was amazed at how heavy it was. I cut it in half and the wood was obviously locust and looked as good as the day it was cut. We harvested some logs from a stand next to the project and slabbed some planks for mud sills. I've started about two thousand seedlings and am seriously considering expanding my business to deal in this amazing wood.
Comment from contributor G:
Black locust is the most durable, gorgeous outdoor wood available. I have a sawmill and every available log I can get I saw. Locust when freshly sawn has a yellow tint. Build your outdoor furniture, set it outside, spray Thompson's waterseal on it and watch it explode over a few days into this beautiful reddish brown. Keep spraying until you have at least five coats of waterseal, then every few months spray again. It soaks it up and stays beautiful.
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