Black locust is the most durable hardwood species in Europe; it is mainly used in outdoor fitting-out because of its high resistance to moisture. It is an ideal alternative to exotic woods, for construction that is more respectful of the environment.
Would you like to know more about black locust wood? WoodPartners explains it all:
- What is black locust wood?
- What are the characteristics of black locust?
- Black locust wood: what is it used for?
- How do you maintain black locust wood?
- Other questions about black locust
What is black locust wood?
Black locust wood, also called "false acacia", is from the Fabaceae family. Often wrongly called acacia, black locust comes from Eastern Europe and its scientific name is Robinia pseudoacacia. Durable, hard-wearing and endowed with impressive longevity, this wood species can remain unchanged for more than 50 years in your various projects.
Black locust grows mainly in temperate climates, at low altitude and in fairly light, airy soil. The trunk of the black locust can measure up to 1 m in diameter thanks to its fast growth and its low demands on the richness of the soil.
Finally, different names are used for black locust wood depending on the country:
- France : Robinier;
- Spain : Robinia;
- Germany : Falsche akazie;
- United Kingdom : False acacia;
- United States : Black locust.
What are the characteristics of black locust?
Black locust is a dense, hard and elastic wood that is very durable. It stands up very well to the various forms of external attack such as moisture, fungi and termites, and is one of the class 4 woods that can be used in contact with water.
Description of black locust
- Colour : yellowish brown to greenish;
- Sapwood (the soft, light-coloured part of the wood that forms each year under the bark): clearly distinct;
- Grain : coarse;
- Grain direction or fibre orientation : straight;
- Interlocked grain or direction contrary to the axis : absent.
Description of the black locust log
- Diameter : between 15 and 50 cm;
- Preservation in the forest : good.
The physical properties of black locust wood
- Density (at 12% moisture content with 1 MPa = 1 N/mm²): 0.74;
- Hardness (at 12% moisture content with 1 MPa = 1 N/mm²): 9.5;
- Volumetric shrinkage coefficient : 0.40%;
- Total tangential shrinkage (TS): 6.9%;
- Total radial shrinkage (RS): 4.4%;
- Ratio between TS and RS : 1.6;
- Fibre saturation point : 30%.
The natural durability and treatability of black locust
- Resistance to fungi : class 1-2, very durable to durable;
- Resistance to dry wood insects : durable;
- Resistance to termites : class D, durable;
- Treatability : class 4, not treatable;
- Use class: class 4, for outdoor use in direct contact with the ground or with fresh water.
Drying black locust wood
- Drying speed : slow;
- Risk of distortion : high;
- Risk of case-hardening (accidental hardening): absent;
- Risk of checks (splits): high;
- Risk of collapse (waviness, separation of the wood): absent.
Sawing and machining black locust
- Blunting effect : normal;
- Sawing teeth : stellite-tipped teeth;
- Machining tools : tungsten carbide;
- Suitability for peeling : good;
- Suitability for slicing : good.
Assembling black locust wood
The assembly of black locust is carried out in two steps:
- Nailing and screwing : good holding, pre-drilling required;
- Gluing : satisfactory.
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Black locust wood: what is it used for?
Black locust wood is a perfect replacement for certain tropical woods such as cumaru for outdoor use: cladding, decks, hydraulic works, bridges and pontoons. With its natural resistance and its class 4 rating, it can easily be used outdoors, in contact with the ground or with fresh water.
- Black locust for external cladding: with its extraordinary durability, it is used for house cladding.
- Black locust wood for hydraulic works: able to be placed in contact with the ground and with fresh water, it is suited to various hydraulic works.
- Black locust in the making of garden furniture: hard-wearing and dense, it makes it possible to produce high-quality garden furniture.
- Black locust wood for fences: this hard wood, which needs no particular treatment, is the ideal ally for guaranteeing the durability of your fences.
How do you maintain black locust wood?
Black locust wood needs very little maintenance and requires no preservation treatment such as pressure treatment, because it is naturally durable and hard-wearing. It takes the application of a saturator perfectly well, which you can use in order to keep the natural shade of the black locust.
What is more, for your black locust decks, we advise you to clean them once a year with water and a light brush to remove any dirt that may have become ingrained in the wood.
