Historically, North American tree species received colorful, descriptive names from the Native Americans who first encountered them. In turn, the colonists early on either adopted those names or chose their own for the tree. Not so with the hackberry. Records from the period make no mention of the even then abundant tree. Maybe it was because hackberry, although a member of the elm family, doesn't look much like an elm. Even its leaves more closely resemble the nasty nettle weed. And its wood, despite being fairly easy to work, was long ignored. Eventually, though, someone called the tree hackberry, and the species at least had a title, if not respect. Today, hackberry still is one of the most neglected hardwoods in North America, but for little explainable reason. Hackberry's first commercial role was as hoops for barrels because of the wood's toughness and flexibility. Now, though, the wood becomes kitchen cabinets, inexpensive furniture, and inevitably, boxes and crates. Increasing demand for it as a substitute for more costly white ash has increased hackberry's volume in the marketplace.
Actually, there are four hackberry species in North America, all looking a lot the same. The common hackberry (Celtis occidentalis) has the greatest range, but a southern hackberry, called sugarberry, produces the most commercial lumber. But the characteristics of each hackberry species remain the same. In fact, they are mixed and sold together. Hackberry grows best in the thick forests of the bottomlands. In fact, along the Mississippi River, specimens nearly 4' in diameter and 120' tall have been recorded. In other areas, hackberry may only attain half that size. Recognizing hackberry isn't difficult. Just look at the bark. Ranging in color from light brown to silvery gray, it usually features ridges and rough, irregular warts. And in summer, hackberry carries 2-4" long, roundish, tooth-edged leaves that end in a sharp point. Small purple, cherrylike fruits (edible by birds) that ripen in the fall. At 37 pounds per cubic foot air-dried, hackberry wood weighs about the same as black walnut and is nearly as hard but not as strong. Yet surprisingly, it outranks walnut in shock resistance. The color of hackberry ranges from creamy white (sometimes with a grayish cast) to a light yellowish tan, with no sharp contrast between heartwood and sapwood. Its grain resembles ash.
Uses in woodworking
Hackberry may look like ash, but it's not as rugged. However, you can use it for furniture such as chairs and tables, and for cabinets, too. You can carve hackberry, but its coarseness isn't very appealing. Woodturners might reject it for the same reason.
Although hackberry's commercial volume has steadily risen over the years, don't expect to find it at a typical retail outlet. The demand just isn't there yet. But local mills within hackberry's range carry it, and large hardwood suppliers can special order the wood. Expect to pay about $1.50 per board foot or less. Veneer isn't available except to the architectural trade. According to a spokesman for a major hardwood producer that processes 10 million board feet of hackberry annually, the wood has only one fault. But it's one you should look out for. Unless harvested in winter when the sap is down, hackberry has the tendency to develop a bluish-gray stain. And, says our source, you might not notice it on the surface of rough-sawn stock until planing. But, the stain does not harm the wood in any way, and like the varying hues in yellow poplar, it does have its own appeal. Should you desire light-colored stock without stain, be sure to buy only surfaced (S4S) stock, and carefully inspect it. Then, follow these suggestions for working this under-appreciated wood.
- Although not nearly as hard as white ash, hackberry does have a blunting effect on cutting edges, so opt for carbide cutters.
- Hackberry has irregular grain. Sometimes the grain runs straight and then again it can be interlocked. When you run into interlocking grain, plane it at a slight angle to avoid tearout.
- Don't force-feed this somewhat dense wood when ripping, as it will burn. And use a rip-profile blade with at least 24 teeth.
- Watch grain direction when jointing this wood. To avoid tearout, the jointer knives should follow the grain direction.
- Because hackberry burns and chips almost as easily as white ash, be sure to take shallow passes with your router. And on end grain and cross-grain cuts, use a backing board.
- Don't skip grits when ding hackberry, as it easily scratches.
- Drill this wood only with bradpoint bits, and lift the bit from the hole occasionally to clear it or you'll burnish and burn the stock.
- Plan on white glue for joining because like ash, hackberry absorbs glue slowly. You'll want plenty of open time.
- Staining hackberry won't cause you any problems, unless you have to compensate for blue-stained wood by going lighter in those areas.
Unlike the much harder white ash, hackberry will yield to carving tools if you like its look. To tackle it, try these tips:
- Deeper bevels of 25-30 degrees will cut better in rough-in work. Then switch to 15-20 degree bevels for finer cuts.
- Avoid splinters along straight grain by taking shorter strokes and using stop cuts.
Should you decide to turn hackberry, take shallows cuts to avoid splintering, and make them with sharp tools.
Any exceptions-and special tips pertaining to this issue's featured wood species-appear under other headings on this page.
- For stability in use, always work wood with a maximum moisture content of 8 percent.
- Feed straight-grained wood into planer knives at a 90° angle. To avoid tearing, feed figured wood or twisted grain at a slight angle (about 15°), and take shallow cuts of about 1⁄32 ".
- For clean cuts, rip with a rip-profile blade with 24-32 teeth. Smooth crosscutting requires at least a 40-tooth blade.
- Avoid using twist drills. They tend to wander in the wood and cause breakout. Use a backing board under the workpiece to reduce tearout.
- Drill pilot holes for screws.
- Rout with sharp, preferably carbide-tipped, bits and take shallow passes to avoid burning.
- Carving hardwoods means fairly shallow gouge bevels-15° to 20°-and shallow cuts.