Sponsored by: Northwest Hardwoods: Lumber that’s Graded For Yield®.
Osage Orange (Maclura pomifera) derived its common name from the Osage Indians in Oklahoma and Texas and the orange-smelling fruits. The Latin name comes from William Maclura, an American geologist (1763-1840), and from the grapefruit-size, heavily wrinkled, spherical pomes or apples (inedible for humans) it produces. Many a farm child has used these fruits for baseballs!
The tree was native to Arkansas, Oklahoma, and Texas, but in the last century the tree has “escaped” and is found throughout the U.S. It is most commonly known as Osage orange, but other names include hedge, hedge-apple, yellow-wood, bowwood, Osage apple, and bodark (from the French bois d’arc, meaning bow wood). The sharp thorns of this tree led to its planting for hedgerows that performed as excellent fences for cattle. It also was widely planted to stabilize erosion during the Dust Bowl.
The extremely high strength of this wood led to its use for archery bows (in the 19th century, a well-made Osage-orange bow was worth “a horse and a blanket”), and for wheel rims and axle hubs for wagons. It is probably the most naturally decay resistant species in north America, leading to its use as fence posts, insulators and insulator pins on telephone poles, and railroad ties. Yet it seems terrible to use such a beautiful wood for non-appearance items. The beautiful coloring has lead to limited use for turnings and novelties, such as wooden pens, as well as for accent wood in musical instruments, substituting for ebony at times. The potential exists for more widespread use, especially as an accent species.
The root wood and bark, and to a lesser extent the wood itself, have a great amount of yellow coloring that can be extracted in hot water and used as dye. Native Americans used this coloring. In World War I, the dye was used for khaki coloring.
Processing suggestions and characteristics
Density. Osage orange averages about 50 pounds per cubic foot at 7 percent MC. This is 30 percent heavier than oak! KD lumber, 1 inch thickness, will weigh over 4 pounds per board foot.
Drying. This wood must be dried quite slowly to avoid checking. However, it does dry without much warp. End coating is essential. Treat 4/4 Osage orange like 8/4 red oak. Shed drying of green lumber before kiln drying is probably best.
Shrinkage in drying is about 5 percent; quite low, especially considering its density.
Gluing and Machining. Gluing is easy with most adhesives.
Machining is difficult due to the high density, but with sharp tools and patience, machining and the finish obtain is excellent with a high luster. Some people do report that the dust causes dermatitis; use good dust control procedures, especially when sanding.
Stability. Osage orange is subject to very small size changes when the MC changes–about 1 percent size change for each 7 percent MC change across the grain parallel to the rings (tangentially), and about 1 percent size change for each 9 percent MC change across the rings (radially). This is extremely low movement. For this reason, final MCs in drying are not as critical as with most other hardwoods.
Strength. Osage orange is exceptionally hard and strong. The bending strength (MOR) is over 20,000 psi (50 percent more than red oak). Hardness is around 2000 pounds (100 percent more than red oak). Stiffness (MOE) averages 1.8 million psi (roughly equal to red oak). The high density means excellent nail and screw holding as well. Pre-drilling of holes for fasteners will often be necessary to avoid splitting.
Color and Grain. The wood is ring porous, like oak and ash, so it has a strong grain appearance. The heartwood color is golden yellow, but this color does age slowly toward a russet brown. The appearance is exceptionally lustrous. If you are looking for an excellent accent species to enhance your products, this is probably the one.