Trembling aspen is a slender, graceful tree with smooth, greenish white bark and distinctive leaves that quiver in the slightest breeze, giving it its name.
Trembling aspen is the most common of the fast-growing, small-diameter species used to make oriented strand board (OSB) and laminated veneer lumber (LVL). Aspen has gained acceptance in the construction market as studs, and its bright white colour is well suited to appearance applications.
It is found throughout BC east of the Coast Range.
Trembling aspen grows in many soil conditions across the BC interior from sea level to 3,000 metres and is especially common in the northeast. It often appears in even-aged, pure stands and has a shorter lifespan than most trees due to its susceptibility to decay. Aspen sprout from root suckers and form clones of individual stems. Many kinds of wildlife use the foliage, twigs and buds for food.
Did you know?
Oriented strand board is a widely used, economical structural wood panel that uses fast-growing species like aspen to make efficient use of forest resources. The panels are made from thin strands of wood sliced from small-diameter roundwood logs or blocks and bonded together with a waterproof phenolic adhesive that is cured under heat and pressure.
Trembling aspen is a deciduous broadleaf tree with smooth greenish-white bark that does not peel. A fast-growing tree, it lives on average 50 to 75 years and rarely more than 150 years. It grows up to 40 metres tall and has distinctive leaves that quiver in the slightest breeze. The leaves are smooth and round to triangular shaped with a flattened stalk that is longer than the leaf. The leaves are dark green on top and paler underneath and turn golden yellow or red in the fall. Male and female flowers grow on separate trees—male catkins are two to three centimetres and female catkins are four to 10 centimetres. The fruit are tiny capsules covered with cottony down.
Aspen is the most common species used for oriented strand board (OSB) and can be used to produce high-quality laminated veneer lumber (LVL) for headers, joists, beams and planks. It can be sawn into studs for construction lumber under National Lumber Grades Authority rules, and there is interest in producing it for millwork.
Indigenous peoples have many uses for aspen, including medicine, food and a source of poles, canoe paddles and bowls. Aspen bark contains salicylates, the original basis for aspirin. Lye made from aspen ashes and animal fat is turned into soap and used to prepare moose hides.
Trembling aspen is often grouped with black cottonwood (Populus balsamifera ssp. trichocarpa) and balsam poplar (Populus balsamifera ssp. balsamifera)—two varieties of the same species. Balsam poplar is used for pulp and construction, and black cottonwood is used to make tissues and other paper products.
Trembling aspen wood is light and soft, with a straight, fine, even-textured grain. It can be used for appearance applications due to its bright white colour. It has good planing and turning performance, good screw retention, and resistance to splitting. It is moderately easy to glue and finishes well.
Appearance and millworking grades can be produced according to National Hardwood Lumber Association rules. The lumber is dried according to end use and customer specifications. Kiln drying inhibits natural staining of the wood, improves its strength and stiffness, enhances its appearance, and increases its resistance to decay and insect attacks.
| Density (kg/m3) | Green | 374 |
| Air dry | 408 | |
| Specific gravity (12% m.c.) | Standard | 0.37 |
| Hardness (N) | Side | 2140 |
| End | 2820 | |
| MOE (Mpa) | Green | 9030 |
| Air dry | 11200 | |
| MOR (Mpa) | Green | 37.6 |
| Air dry | 67.6 | |
| Compression parallel (Mpa) | Air dry | 36.3 |
| Compression perpendicular (Mpa) | Air dry | 3.52 |
| Shear (Mpa) | Air dry | 6.76 |
| Cleavage (N/mm width) | Air dry | 45.5 |
| Shrinkage OD = oven dry air = air dry 12% | Radial (OD) | 3.6% |
| Tangential (OD) | 6.6% | |
| Volumetric (OD) | 11.8% | |
| Volumetric (air) | 8.3% | |
| Tang / rad ratio | 1.8 |
| Colour | |
| Heartwood | Varies from off-white to creamy to light greyish-brown. |
| Sapwood | Nearly white. |
| Heartwood / sapwood contrast | There is no distinct colour boundary between sapwood and heartwood to clearly delineate one from the other. |
| Latewood / earlywood contrast | The diffuse porous nature of this species makes growth ring recognition difficult. |
| Grain | |
| Straight-grained, fine and even-textured. | |
| Figure | |
| Plainsawn lumber or rotary-cut veneer: faint growth rings. | |
| Quartersawn lumber or quarter-sliced veneer: none. | |
| Knots | |
| Discolouration above and below knots form and a “comet-tail” or “keyhole” | |
| Other | |
| It has a characteristic disagreeable odour when wet, but is odourless when dry. Wood is soft and light. It weathers to a light grey with a pronounced silky lustre. | |
| Process | Performance | Comments |
|---|---|---|
| Machining | ||
| Planing | Good planing quality | Recommended planer settings: 12° or 20° hook angle and 16 or 20 kmpi (knife marks per inch). |
| Turning | Good surface quality | Common defects: torn out grain and, less severe, fuzzy grain. Sanding usually eliminate these defects. |
| Sawing | Resistance to sawing varies widely | Moderately good when compared to other lower-density wood species but poor when compared to higher-density hardwoods (e.g. maple). |
| Boring | Moderate quality | Recommended settings: use brad point bit. |
| Mortising | Very good | Very good mortising quality when using a hollow chisel mortise. |
| Shaping | Very good | |
| Veneering | Easy | |
| Sanding | Good | Heavily affected by fuzzy grain. Recommended settings: finer sandpaper after the initial sanding to eliminate fuzzy grain and the sandpaper frequently changed. |
| Fastening | ||
| Screwing | Good | Good holding. Good resistance to splitting. Average screw retention: 482 lb. |
| Nailing | Satisfactory | Good resistance to splitting. |
| Gluing | Moderately easy | Good adhesion. |
| Finishing | ||
| Staining | Good | Finishes well. Blotches appear as the stains become darker. Recommended: light to medium stains. |
| Painting | Good | |
| Lacquering | Good | Performed well in the tape test. |
| Waxing | Satisfactory | Best when using light-coloured waxes (e.g. mellow pine). |
| Heartwood durability | ||
| Natural decay resistance | Low | Low decay resistance limits age of trees. |
| Treatability | Very good | Very permeable wood. |
