White Spruce and Engelmann Spruce
White Spruce
Within British Columbia, white spruce (Picea glauca) and its hybrids are found throughout the Interior from the east slope of the Coast Range eastwards throughout the rest of the province. White Spruce can be found in the south of the province, but it is much more prevalent in the northern regions where it often succeeds poplar and pine in many burned areas. It can reach up to 45 metres in height and 1 metre in diameter. While white spruce commonly forms pure stands within its geographical growing range, it also is a major component of mixed stands. Common associates to white spruce include: trembling aspen, white birch, balsam fir, tamarack, black spruce, jack pine, lodgepole pine and Douglas-fir.
Engelman Spruce
Engelmann spruce (Picea engelmannii) occurs at high elevations and interbreeds with white spruce in areas where their ranges overlap, and they are referred to as Interior spruce.
The wood of these two spruce species cannot be differentiated visually. Engelmann spruce wood is slightly denser, harder and stronger than that of white spruce, but the differences are very minor.
All British Columbian species of spruce, including Sitka spruce, account for 22% of the province’s total forest inventory and, of this, white spruce makes up the largest portion of the growing stock.
Common Uses
White spruce wood is highly valued for lumber, plywood and pulp production. As dimension lumber, white spruce is extremely versatile because of its high strength-to-weight ratio. It is used in building construction (framing, sheathing, roofing, sub-flooring), general millwork, interior finishing, boxes and packing cases. Its dimensional stability and superior gluing properties make it popular in the prefabrication industry. White spruce is used in the manufacture of modular houses, trusses, and other structural components that specify kiln-dried SPF wood. As a premier pulpwood, the species is used in the manufacture of newsprint and bleached Kraft pulps. It is also used in the manufacture of medium density fiberboard (MDF), paperboard and felt, and it is a major species used in Canadian softwood plywood. Other uses of white spruce include: sounding boards in musical instruments from select materials, food containers (because it is almost colourless and odourless when dried), paddles and oars, cooperage, organ pipes, shelving, and ladder rails.
Spruce 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 | 306 |
| Air Dry | 390 |
| Specific Gravity (12% M.C.) | Standard | 0.36 |
| Hardness (N) | Side | 1880 |
| End | 2470 |
| MOE (Mpa) | Green | 7930 |
| Air Dry | 9930 |
| MOR (Mpa) | Green | 35.2 |
| Air Dry | 62.7 |
| Compression Parallel (Mpa) | Air Dry | 36.9 |
| compression Perpendicular (Mpa) | Air Dry | 3.45 |
| Shear (Mpa) | Air Dry | 6.79 |
| Cleavage (N/mm Width) | Air Dry | 38.7 |
Shrinkage
OD=oven dry
air=air dry 12% | Radial (OD) | 3.2% |
| Tangential (OD) | 6.9% |
| Volumetric (OD) | 11.3% |
| Volumetric (air) | 6.8% |
| Tang / Rad ratio | 1.6 |
Working Properties
Spruce has a high strength-to-weight ratio and is well known for its working properties. The wood dries rapidly with small dimensional movement and little tendency to check. 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 moderately easily, has moderate nail and screw holding ability, and takes a good finish.
| Process | Performance | Comments |
|---|
| Machining |
|---|
| Planing | Easy. Good quality | Good planing quality. Typical defect is raised grain. Recommended planer settings: 12o or 20o hook angle and 20 kmpi (knife marks per inch). |
| Turning | Satisfactory | Satisfactory surface quality when using rotary-knife lathe and poor when using a single point lathe. Common defect: torn out grain. |
| Sawing | Good | Easily worked with hand and power tools. Slight to moderate blunting effect. While knots can sometimes be a problem, the wood can be sawn cleanly, with sharp cutting edges. |
| Boring | Medium quality | Medium boring quality using brad point bits. |
| Mortising | Good | Very good mortising quality using both a hollow chisel and a chain mortise. |
| Shaping | Good | Good shaping quality. Common shaping defects in the order of frequency: splintering at the corner, rough end-grain, fuzzy grain, raised grain, and torn grain. Recommended: the use of a counter piece for end-grain shaping. |
| Veneering | N/A | |
| Sanding | Very good | |
| Fastening |
|---|
| Screwing | Satisfactory to good holding | Very good resistance to splitting. Average screw retention: 347 lb. |
| Nail Retention | Satisfactory to good holding | Very good resistance to splitting. |
| Lateral Nail Holding | Moderate | |
| Gluing | Moderrately easy to glue | |
| Finishing |
|---|
| Staining | Good | Good staining properties. A smooth finish is achieved. A natural finish (clear coat) or a light stain looks the best. |
| Painting | Satisfactory | |
| Lacquering | Good | Good results. Performs very well in the tape test (i.e. small flakes of the coating were detached at intersections of cuts, less than 5% of the area affected) and well in the pull-off test (i.e. average strength of 31 kg/cm2). |
| Waxing | Good | Easy and with good results. Best when using light-coloured waxes (e.g. Mellow Pine). |
| Drying |
|---|
| Ease of Drying | Easy to moderately easy | Spruce dries faster than pine and is not adversely affected by severe high-temperature schedules. |
| Durability |
|---|
| Natural Decay Resistance | Non-resistant to heartwood decay | |
| Treatability | Very resistant to impregnation with preservatives | |
Commercial Availability
White spruce and Engelmann spruce are produced predominantly as SPF lumber in structural grades according to National Lumber Grades Authority (NLGA) rules for dimension lumber. Select Structural, #2 and better, and stud grades are the most common grades produced. Specialty in-house grades, lamstock and export grades are also available.
Appearance grades are also produced according to NLGA rules. Clears, shop lumber and moulding stock are most common, though there are many potential appearance grades that can be produced.
Sources
BC Wood Specialties Group, www.bcwood.com
Council of Forest Industries, www.cofi.org