Wood for Outdoor Furniture:
Acacia is a thick, strong hardwood with high oil content. This hardwood is resistant to the elements, rotting and insects. Acacia is very abundant, making it one of the more affordable options. James Armstrong, a woodworking consultant from Wood Blinds Direct, says “if you’re thinking about the environmental impact of your wooden furniture, you should go with a fast-growing hardwood, like acacia. It’s durable, and resists the elements well (and is often used in boat-building for its abundance and resistance to water). Once sealed, acacia is a rich, dark, golden brown.” If left unsealed, it can discolor if it is regularly exposed to water. With that being said, I advise to keep acacia furniture off the grass or ground as it will have a tendency to absorb moisture.
2. Black Locust
Black Locust is one of the strongest and stiffest domestic woods. It competes with Hickory for the title of strongest, but has more stability and rot resistance. This makes it very durable with good weathering characteristics.
Black Locust is moderately easy to work with. The Wood Database states “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.” This can be an affordable wood with great uniform patterns to use for making tables or benches.
Jacob Aune is familiar with Black Locust. “Its decay resistance is notable enough to be mentioned in a study by the Louisiana State University on wood decay prevention. Because of its exceptional strength, this is the species to use in outdoor applications where structural integrity is important. It is tougher than white oak and also offers better longevity in outdoor environments.” Aune is the owner of Altare Design, a custom woodworking service based in South Chicagoland near Kankakee, Illinois.