Aspen, also known as aspen poplar, poplar (especially outside North America), popple, trembling aspen, bigtooth aspen, quaky and a dozen other local names is a wonderful wood for many use. The trees and lumber called aspen is from two trees, mainly trembling aspen (Populus tremuloides) and a little bit of bigtooth aspen (P. grandidentata). Lumber from the two species can be mixed and would not separated.

Aspen wood is lightweight and fairly weak and bendable. But, in spite of these somewhat negative features, the wood is very desirable for many uses including children’s toys, tongue depressors, and paneling and seats in saunas. Why? Because this wood is 100% splinterless.

Aspen trees are found mainly in Northeastern U.S., the Lake States, northward into Canada, and in the Rockies from New Mexico north into Alberta. In fact, aspen is the most widespread hardwood species in North America. Incidentally, in the Rockies, this is major hardwood species. It provides natural fire breaks, rapid soil stabilization after a forest fire with a shallow root system and with the broad leaves slowing rain drops, excellent browse for big game animals, wonderful scenic beauty, and an important wood for beavers, voles and many other forest creatures. Although the tree is a prolific seeder, most reproduction is by root sprouting. When the roots are disturbed and there is lots of sunlight, new trees sprout with as many as one million sprouts per acre.

In past years, the wood has been widely used in the areas where it grows for local uses, including log cabins, home and barn framing, and so on. It has also been widely used for paper manufacturing, making paper especially soft and absorbent. Aspen was also used in summer kitchens, as the wood would ignite quickly and burn quickly, supplying the needed heat for cooking, but then would quickly burn up and not keep the kitchen excessively hot. (Quite a difference when compared to oak or hickory, which can burn for hours.) Another popular use for aspen is for pallets, where the wood’s low weight is an advantage when shipping. Aspen has typically been considered as a low grade species. The lack of large clear pieces of high quality lumber have made this species fairly unpopular in the national trade. It has been only in the last decade that the Hardwood Market Report included aspen lumber in its weekly lumber price listings. Large sized, clear lumber is used for caskets.

[A brief note about the genus called Populus. There are at least eight North American species that we see on the commercial lumber market, including trembling aspen, bigtooth aspen, balsam poplar (a.k.a. black poplar, or balm of Gilead; P. balsamifera), Eastern cottonwood (P. deltoides), and black (California cottonwood; P. trichocarpa). I have seen balm of Gilead lumber included with aspen (and it is usually called balsam poplar then.), but there is a big difference in color and drying properties; it would not be accepted by the National Hardwood Lumber association. In Europe and other continents, they also have species that are in the Populus genus. It would not be uncommon to hear all of these, from time to time, except for Eastern cottonwood, called "poplar," because they are in the Populus genus. However, the properties and color vary widely at times when comparing the various species in this genus.]

One other name concern: The name "poplar" can sometimes be used for aspen, but this name in North America is more often used for American tulipwood, which we know as yellow-poplar or tulip poplar. The Latin name for this tree is Liriodendron tulipifera. Its leaves are shaped like a tulip flower (if you use a small bit of imagination); hence the use of "tulip" in the species name. Note that it is not in the Populus genus. Yellow-poplar is a much denser, stronger, and stiffer wood than the species in the Populus genus.

Processing suggestions and characteristics

Density. Dry aspen lumber at 7 percent MC averages about 25 pounds per cubic foot, making it the lightest native hardwood. A planed and dry 1 x 6 x 10' piece of aspen will weigh only 8 pounds.

Dry aspen lumber at 7 percent MC averages about 25 pounds per cubic foot, making it the lightest native hardwood. A planed and dry 1 x 6 x 10' piece of aspen will weigh only 8 pounds.

Drying. Aspen is one of the easiest woods to dry, unless it is bacterially infected. Drying rates can be as rapid as possible. Slow drying initially can quickly lead to blue stain.

Aspen is one of the easiest woods to dry, unless it is bacterially infected. Drying rates can be as rapid as possible. Slow drying initially can quickly lead to blue stain

Bacterially infected wood is higher in initial green MC, has an objectionable odor, does not release the moisture easily in drying so that wet pockets develop in lumber, will show excessive shrinkage or collapse, and may have a slight, darker discoloration. Bacterial infections are almost always found in the heartwood. Wet pockets are small regions within a piece of 6/4 and thicker lumber (a typical size is 1/2" deep x 1" wide x 6" long) that have much higher moisture content than the surrounding wood. Long drying time is the only cure for wet pockets.

Shrinkage in drying is around 6 percent, green to 7 percent MC. Because the wood is so weak, fuzzing is likely unless the wood is under 7 percent MC. Oftentimes, final MCs will be between 5 to 6 percent MC, a bit drier than for other hardwoods.

Gluing and Machining. Aspen is the easiest of all native American species to glue. It is very forgiving. However, the wood is very absorptive, so that pressure must be applied ASAP after the glue is applied or else the glue will dry out and not bond well.

Aspen is the easiest of all native American species to glue. It is very forgiving. However, the wood is very absorptive, so that pressure must be applied ASAP after the glue is applied or else the glue will dry out and not bond well.

Due to the fuzzing problem, caused by the weak fibers in aspen, in addition to low final MCs, the tools must be extremely sharp. High speed steel is recommended rather than carbide. Likewise, only fresh sandpaper (particles are sharp) should be used. A sizing coat or sanding sealer is often used to stiffen the fibers and eliminate the fuzzing problem.

Stability. Once dry and any wet pockets are dried as well, the wood is very stable. It changes 1 percent in size tangentially with a 6 percent MC change (about 30 percent RH change) and 1 percent in size radially for a 10 percent MC change (50 percent RH).

Once dry and any wet pockets are dried as well, the wood is very stable. It changes 1 percent in size tangentially with a 6 percent MC change (about 30 percent RH change) and 1 percent in size radially for a 10 percent MC change (50 percent RH).

Strength. Aspen is quite weak, being half as strong, or less, than red oak. The bending strength (MOR) is 8400 psi and the elasticity is 1.2 million psi. The hardness is only 350 pounds. Nevertheless, aspen is still strong enough to be used for studs in home building, pallets, and some other structural uses. If used where its strength is of concern, larger sizes can increase the strength.

Aspen is quite weak, being half as strong, or less, than red oak. The bending strength (MOR) is 8400 psi and the elasticity is 1.2 million psi. The hardness is only 350 pounds. Nevertheless, aspen is still strong enough to be used for studs in home building, pallets, and some other structural uses. If used where its strength is of concern, larger sizes can increase the strength.

When nailing ro screwing aspen, the heads can easily pull through partially or fully. Larger headed nails and screws are suggested, along with larger diameters and more fasteners in a joint. However, as aspen can be nailed near the end without splitting, nails do have good strength compared to species that like to split when nailed near the end.

Color and Grain. Both the sapwood and heartwood are white in color and cannot be easily separated. The grain and texture is fine with the annual rings very difficult to see easily. Splinterless-ness is a key feature.

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