Red Alder
Red alder (Alnus rubra) is the most plentiful hardwood on the Coast of British Columbia, though hardwoods make up only 5.4% of the province's total growing stock. It is a short-lived tree – with an average life span of 40 to 60 years that tends to grow in pure stands. A medium-sized broad-leaf tree, it grows up to 24 metres tall and 60 cm in diameter. Red alder is a fast growing tree that does not tolerate shade, and therefore, occupies a site quickly after a disturbance.
Common Uses
Red alder has been increasing in popularity over the past few years. It is a very important local species for furniture, flooring, cabinets, turnery, decorative veneer, and other home decorations, as well as craft products such as domestic woodenware and toys. Other high value products produced from red alder are doors, shutters, mouldings, panel stock and carvings. Lower grade wood is often used in plywood core stock, chips for pulp and paper, as well as for firewood, charcoal, and chips for smoke curing.
Red alder lumber is dried according to end-use and customer specifications. Kiln drying inhibits natural staining of the wood, enhances its appearance, and increases its resistance to decay and attack by insects.
| Physical Properties |
|---|
| Density (kg/m3) | Green | 373 |
| Air Dry | 390 |
| Specific Gravity (12% M.C.) | Standard | 0.37 |
| Hardness (N) | Side | 2490 |
| End | 4360 |
| MOE (Mpa) | Green | 8270 |
| Air Dry | 10100 |
| MOR (Mpa) | Green | 43.4 |
| Air Dry | 73.8 |
| Compression Parallel (Mpa) | Air Dry | 40.0 |
| compression Perpendicular (Mpa) | Air Dry | 4.00 |
| Shear (Mpa) | Air Dry | 7.96 |
| Cleavage (N/mm Width) | Air Dry | 53.4 |
Shrinkage
OD=oven dry
air=air dry 12% | Radial (OD) | 4.2% |
| Tangential (OD) | 7.0% |
| Volumetric (OD) | 11.7% |
| Volumetric (air) | 8.0% |
| Tang / Rad ratio | 1.7 |
Working Properties
Red alder is light in weight with medium strength and hardness, and it is well known for its working properties. The wood dries well, but care must be taken to control the colour. It is relatively easy to work, with good machining qualities. It turns, planes and shapes well and can be sanded to a smooth finish. The wood glues easily, has moderate nail and screw holding ability, and takes a good finish.
| Process | Performance | Comments |
|---|
| Machining |
|---|
| Planing | Excellent planing quality | Recommended planer settings: 20o hook and 12, 16, or 20 kmpi (knife marks per inch). No major defects. |
| Turning | Medium to good surface quality | |
| Sawing | Easy to work with tools | |
| Boring | Medium | Medium to good boring quality with brad point bits and lower quality with single twist bits. |
| Mortising | Good to moderate | Good mortising quality when using a hollow chisel mortise. |
| Shaping | Good shaping quality | Recommended: the use of a counter piece for end-grain shaping. |
| Veneering | N/A | |
| Sanding | Good | Excellent sanding quality. |
| Fastening |
|---|
| Screwing | Good -moderate | Average screw retention: 518 lb. |
| Lateral Nail Holding | N/A | |
| Nail Retention | Good | |
| Gluing | Easy | Bonds very easily with adhesives of a wide range of properties and under a wide range of bonding conditions. |
| Finishing |
|---|
| Staining | Easy to moderately easy | Attractive natural colour. Light stain works well. Blotchy when dark stain used. Smooth finish achieved. |
| Painting | Average to good paint holding ability | |
| Lacquering | Good | Performed well in the tape test (i.e. edges of the cuts were completely smooth; none of the squares of the lattice was detached) and in the pull-off test (i.e. average strength of 29 kg/cm2). |
| Waxing | Good | Excellent results are obtained when using light- to dark-coloured waxes (e.g. Mellow Pine, Chestnut, and Jacobean). |
| Drying |
|---|
| Ease of Drying | Moderate | The colour of the wood is affected by the temperature and humidity of the schedule. |
| Durability |
|---|
| Natural Decay Resistance | Non-durable | Logs should be processed quickly, particularly during warm weather, as decay proceeds rapidly. Green lumber should be carefully stacked for air-drying or promptly kiln dried to prevent damage from microbial stain. |
| Treatability | N/A | |
Commercial Availability
Red alder is the most available of BC hardwoods. Appearance and millworking grades are produced according to National Hardwood Lumber Association (NHLA) rules. Common grades include Select and better, #1 shop, and framegrade. A number of proprietary grades also exist.
Sources
BC Wood Specialties Group, www.bcwood.com