Trembling Aspen
Trembling aspen (Populus tremuloides) – grouped together with balsam poplar – makes up approximately 3 to 4% of British Columbia’s forests. The tree often appears in pure stands and grows in many soil conditions from sea level to 3000 metres. This tree grows up to 25 metres tall and 25 cm in diameter, but has a shorter lifespan than most trees due to its susceptibility to decay.
Common Uses
Aspen is the most commonly used wood species for oriented strand board (OSB). It is suitable for the production of high quality laminated veneer lumber (LVL) for use as headers, joists, beams and planks. Aspen lumber has gained moderate acceptance in the construction market as studs. There is interest in marketing aspen for appearance applications due to its bright white colour.
Aspen 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 attack by insects.
| Physical Properties |
|---|
| 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 |
| Process | Performance | Comments |
|---|
| Machining |
|---|
| Planing | Good planing quality | Recommended planer settings: 12o or 20o 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 G | 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). |
| Durability |
|---|
| Natural Decay Resistance | Low | Low decay resistance limits age of trees. |
| Treatability | Very good | Very permeable wood. |
Commercial Availability
Aspen is currently sawn into studs for construction lumber under National Lumber Grades Authority (NLGA) rules. However, the main interest is to increase the production of aspen for millwork applications. Appearance and millworking grades can be produced according to National Hardwood Lumber Association (NHLA) rules.
Sources
BC Wood Specialties Group, www.bcwood.com