There are two trees, hackberry (Celtis occidentalis) and sugarberry (Celtis laevigata), that produce the lumber known as hackberry. That is, in the trade, the names hackberry and sugarberry are used interchangeably. Sometimes the lumber from these species is called sugar hackberry. We will use the name hackberry here, but we will be referring to both species.
The species grows from North Dakota to Texas to North Caroline to Quebec, but the Southern states seem to have the best supply. Trees are often over 100 feet tall, although 75 feet is more common. The berries are edible, but because they are so high, the birds have their feast before they can be harvested.
Hackberry is a lumber species that does not stand on its own too often. Rather, it has been used as a substitute for red oak, ash or elm. Indeed, hackberry has strong grain and porous structure, so it is quite similar to these other three species.
Perhaps the greatest detriment to using hackberry is that it stains (fungal stains and chemical enzymatic oxidation gray stains) very quickly. Logs that have been held in warm weather or lumber that have not been promptly stacked and dried aggressively right after sawing will almost always have high staining risk.
Careless lumber producers will produce mostly “paint grade” hackberry because of the stain. However, with reasonable care, hackberry is a beautiful wood, worth the high prices paid for the better grades of ash and elm. It certainly makes fine furniture and cabinets, but does not get as much use as “show wood” as I think it should. As the TV ad says: “Try it; you’ll like it!”
Processing suggestions and characteristics
Density. Hackberry has a density of approximately 35 pounds per cubic foot. Hackberry KD lumber weighs about 3 pounds per board foot at 7 percent MC.
Drying. The wood is very prone to staining if not handled and dried promptly. Using initial temperature in the kiln of 115F with very low initial humidities also helps to produce lighter colors. A weak solution of oxalic acid (wood bleach) will remove most of the enzymatic stain on the surface of dry lumber or parts, rough or sanded. Hackberry has 7% shrinkage from green to 6 percent MC.
Gluing and machining. Hackberry glues fairly easily. The wood machines easily. If over-dried, chipped grain may be encountered.
Stability. Hackberry has a 1-percent size change in width (or tangentially) for flatsawn lumber for each 3.4 percent MC change and 1 percent thickness change (radially) for a 6 percent MC change.
Strength. The strength (MOR) at 12 percent MC is 11,500 psi, the stiffness (MOE) is 1.19 million psi, and the hardness is 880 pounds.
Color and grain. This species is ring porous, so it has a region of large pores at the beginning of every ring, just like oak, ash, and elm. The sapwood is typically pale yellow. The heartwood, which often is not present, is yellowish gray or yellowish-brown. The wood can be finished naturally (I think it has excellent, attractive appearance when done “au natural.”) or it can be stained to closely resemble oak, ash and elm.
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