Black locust



Robinia pseudoacacia

black locust

Quick Stats
Common Names: yellow locust

Habitat: Grows naturally on a wide range of sites but does best on rich moist limestone soils

Description: Because it is a nitrogen fixer and has rapid juvenile growth, it is widely planted as an ornamental, for shelterbelts, and for land reclamation

Uses: Black locust is not a commercial timber species


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.


Robinia pseudoacacia L. Black Locust

Special Uses
Although black locust is not an important timber tree in the United States, it is used for a wide variety of products and is planted for many specialized purposes. It is used for fence posts, mine timbers, poles, railroad ties, insulator pins, ship timber, tree nails for wooden ship construction, boxes, crates, pegs, stakes, and novelties. Pulp with satisfactory mechanical properties can be made, particularly by the sulfate process (35). It is also suitable for use in fuel plantations (14,16).

From: Robert Thompson's site,

About the wood

The woods I commonly use in building boats are all highly rot resistant:

Pepperwood or California Bay Laurel (Umbelluria californica)

An evergreen tree with long oval leaves 3-6". Leaves have strong spicy odor. Bark is grey and flaky, commonly moss-covered. Small green flowers in early spring, producing green nutlets. Growth tends to broad spreading crown with large trunk. Native along west coast from Oregon down to central California.

Characteristics of Wood: Slightly hard and moderately light. Wood pale white when freshly cut, oxidizing to reddish tan, commonly with blue/purple mineral streaks. Freshly cut wood has same odor as leaves, but weaker. High strength relative to weight. Extremely dimensionally stable with moisture change. Grain very wavy and therefore difficult to work with edge tools. Tends to resist splitting and abrasion well. Trees reach enormous size and produce clear wood as well as grown shapes. Very rot resistant if growing at elevation, very poor resistance otherwise. Reason for distinction unknown.

Black Locust (Robinia pseudoacacia)

A deciduous tree with many small pinnately compound leaves, dark blue green in color. Dark brown bark thickly furrowed into long forking ridges, often with a grey lichen coating. Flowers in late spring with many clusters of showy white blooms. Fruit consists of long seedpods. Growth form tends toward many upright crooked branches. Native to eastern central U.S., but now naturalized from Maine to California. Planted widely for shelterbelts and ornamentals. Grows and spreads rapidly.

Characteristics of Wood: Extremely hard and heavy. Wood having yellow-green cast when freshly cut, oxidizing to a faint orange. Very strong, possibly the strongest native timber per dimensional unit. Grain tends to be wavy, making it difficult to work with edge tools, as well as difficult to split. Crooked branching growth form makes clear lengths difficult to find but produces many useful "grown" shapes. When straight grained, locust bends very well with steam. Extremely rot resistant.

Black Cherry (Prunus secortina)

A deciduous tree with single elliptical leaves 2-4" long. Smooth dark-grey bark becoming fissured and scaly. Growth tends to long upright trunk and uneven crown. Small white flowers spread along drooping stem appear in mid-spring. Native and common east of the plains. Cherry is heavily harvested for furniture and paneling.

Characteristics of Wood: Moderately hard and heavy. Wood pink when freshly cut, oxidizing to dark red/maroon over time. Tough and flexible, cherry steam bends well. It often grows with wavy grain, creating problems in tooling with blades. Growth form makes clear lengths readily obtainable.

Northern White Cedar (Thuja occidentalis)

An aromatic evergreen with small pointed needles growing in flat opposite pairs. Light reddish brown bark growing in narrow shedding strips. Produces small upright elliptical cones. Except in dense stands, this cedar grows with many branches in tall narrow cone. Native from New York north to S. Canada, Maine west to Minnesota.

Characteristics of Wood: Soft and extremely light. Wood ranging from white to reddish. Good strength relative to low weight and tends to be flexible. Very dimensionally stable with moisture changes. Grain tends to be even and consistent, making it a joy to work with edge tools. Resins tend to build up on cutting points of power tools. Unfortunately clear lengths difficult to obtain. Very rot resistant.


Schooner Sail by Thomas Lannon site, from press release on building a traditional 65' wooden schooner.

"Burnham and a team of craftsmen worked long hours, regardless of the weather, to complete the schooner in just eight months. They used locally grown white oak and black locust trees for the frame. For the 70-foot masts, they used white spruce."


Wood: Black locust wood is strong and hard with a specific gravity of 0.68, yet it has the lowest shrinkage value of US domestic woods. The wood makes a good charcoal. Wood energy yield is typical of temperate broadleaf trees, about 19.44 x 106 J/kg (Stringer and Carpenter 1986). The beautiful light to dark brown wood is used to make paneling, siding, flooring, furniture, boat building (substitute for teak), decking, vineyard or nursery props, fruit boxes, and pallets. It is also a preferred wood for pulp production. Black locust wood is highly resistant to rot (Smith et al. 1989).

...Another point on the Black Locust and possible lack of commercial use, is that the majority trees I have seen are rather spindly and very crooked, minimizing the yield for conventional lumber, but being favorable for sawn frames, following the curvature of the limbs. In my experience, the wood turns on a lathe beautifully, has a nice warm yellow to amber color. It is also very tough and awful to try and split for firewood.
Mark Bronkalla

This is evidently not the case in all of its range. I don't remember for sure where, but in part of its range, black locust grows to tall straight trees. ...brw

I would add that several sites I visited were devoted to the best way to get rid of black locust. It tends to be very prolific and to crowd out native plants outside its natural range and can become a nuisance.
If anyone else has any input on black locust or any other "alternative boatbuilding lumber", please share it with your fellow boatbuilders.