A new home: while plywood has largely replaced sweetgum in the furniture market it once enjoyed, a new application awaits.

Sweetgum (Liquidambar styraciflua) is considered a Southern species, but the tree actually grows from Connecticut west to Illinois and Missouri, and south from the East Coast to the Gulf of Mexico. Commercial supplies of sweetgum come mostly from the Southern and South Atlantic states; with Arkansas, Louisiana and Mississippi being major contributors.

According to the U.S. Department of Agriculture Forest Products Laboratory Wood Handbook, "The lumber from sweetgum is usually divided into two classes--sap gum, the tight-colored wood from the sapwood, and red gum, the reddish brown heartwood." At one time, the commercial name for sapwood was hazel pine white heartwood was sometimes called satin walnut.

Sweetgum is usually a white to pink-white color. The material can stain blue because of sap stains. It usually features a plain look, but the interlocked grain can yield a ribbon stripe. Red gum, the material from the heartwood, is reddish brown in color, often with dark streaks and interesting figures.

White red gum is used for architectural interiors and cabinet making, sweetgum is used for lumber in the production of boxes, crates, furniture, cabinetry, interior trim and millwork. Sweetgum veneer and plywood is used for cross-banding, pallets, crates, boxes and baskets, as well as interior woodwork. The wood was traditionally used for upholstered furniture frames, but a decade or so ago the market for frame stock turned to plywood instead of sweetgum.

Rubin Shmulsky, a forest products associate professor from Mississippi State University's (MSU) Forest and Wildlife Research Center, collaborated with Anthony Hardwood Composites Inc. in a project to "explore the possibility of making a high-value composite from sweetgum lumber. Our primary goals were to assess strength properties, technical feasibility and lumber yield," Shmulsky said.

Why sweetgum? "We studied it because we had plenty of sweetgum, but not enough markets," Shmutsky said. "Sweetgum is a relatively low-grade hardwood and it can warp and twist and be somewhat unruly. It was often used as furniture frame stock, the wood inside a recliner or couch, but that market turned to plywood, which is slightly more consistent than sweetgum and cheaper to process."

Shmulsky added that the switch to plywood left a lot of low-grade sweetgum on the market without a home. "We helped to develop a laminated mat that we think is a promising new market for sweetgum."

MSU manufactured composite beams from sweetgum lumber. Karen Brasher, publications editor for the College of Forest Resources at MSU, said the lumber was sorted, planed, chopped and glued into 6-inch by 12-inch-deep laminated sweetgum beams, which were then put through a series of rigorous tests.

"The mat that we helped to develop is 6 inches thick and just as strong as a 12-inch-thick oak mat," Brasher said. "The industrial matting is used in remote areas as ground flotation material. The mats support heavy equipment needed at construction sites, dispersing vehicular loads with minimal damage to soil."

"There are many benefits to using sweetgum rather than oak. One benefit is that each sweetgum mat uses less wood than the oak mats," said Shmulsky. "Another benefit is that you can put more mats on a truck or rail car--such as 40 sweetgum mats to 20 solid oak mats, which saves freight.

"It is also a 'green' product because the lower grade sweetgum used in the mats comes from highly abundant trees that grow and mature faster than oak trees. A large oak takes 40 years to grow. Sweetgum has the advantage of retting us develop a product with the same strength properties in a much faster growing tree."

Brasher said the success of the project has allowed Anthony Hardwood Composites to design, build and begin operating a commercial factory to produce the industrial matting.

John Fiutak, general manager of the new facility, said the sweetgum is turned into individual laminated beams which are assembled into the industrial mats.

Shmulsky said that the mats can be used in the United States and also exported to other countries. "It is the kind of portable material used in remote areas, designed so that heavy equipment can drive over them in areas without roads. It is good news for sweetgum. The other uses for higher grades of sweetgum and red gum remain, but for the lower grades, this offers a great new market."

Family Name

Liquidambar styraciflua of the Family Hamamelidaceae 

Common Names

Sweetgum, sap gum, red gum, alligator-tree, alligator wood, hazel pine, incense tree, liquidambar, satin walnut and star-leaved gum

Height/Weight

Trees can grow to heights of 120 feet, but average from 80 to 100 feet. Average weight is 37 pounds per cubic foot.

Properties

Experts recommend drying with care to minimize distortion and warping, especially with material featuring irregular grain.

Wood is moderately hard and strong, moderately stiff and moderately high in shock resistance.

Rated as generally easy to work; glues, finishes well.

Editor's note: 139 Wood of the Month articles are now online, with more coming soon. Visit the Wood of the Month archive at www.iswonline.com.