Wood species
Black spruce wood
Black spruce is a softwood (Picea mariana). At 12% moisture content it has a Janka hardness of 530 lbf (2,358 N) and it weighs about 29 lb/ft³ (470 kg/m³), 2.4 lb (1.11 kg) per board foot.
Also called: Picea mariana.
Key numbers
- Janka hardness, 12% MC
- 530 lbf (2,358 N)
- Green: 340 lbf (1,512 N)
- Weight at 12% MC
- 29 lb/ft³ (470 kg/m³)
- 2.4 lb per board foot
- Specific gravity (oven-dry weight)
- 0.42 at 12% MC volume
- 0.38 on green volume
- Shrinkage, green to oven-dry
- 6.8% tangential
- Radial 4.1%, volumetric 11.3%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; black spruce's density is worked from its specific gravity with the Handbook's own equation.
How much black spruce moves
A 12 in wide flatsawn board of black spruce that goes from 6% to 12% moisture content swells about 0.17 in (about 5/32 in, 4.3 mm). Quartersawn, the same board moves about 0.1 in (about 3/32 in, 2.6 mm). Flatsawn faces move 1.7 times as much as quartersawn ones, because the wood shrinks 6.8% around the growth rings but only 4.1% across them.
Worked with the Wood Handbook's dimensional change coefficients for black spruce (Table 13-5: 0.00237 tangential, 0.00141 radial per 1% change in moisture content), which hold between 6% and 14%. Individual boards vary: the Handbook gives shrinkage a coefficient of variation of about 15% (p. 4-11).
Color, grain and working
- Color
- Light in color, with little difference between heartwood and sapwood.
- Working and character
- The Handbook describes the eastern spruces together: they dry easily and are stable after drying, moderately light, easily worked, with moderate shrinkage, and moderately strong, stiff, tough and hard.
- Uses
- Mostly pulpwood; the lumber goes into framing, millwork, boxes and crates and piano sounding boards.
Red, white and black spruce have about the same properties and are not told apart in commerce.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-17 to 2-18.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of black spruce tested by the Forest Products Laboratory (Wood Handbook Table 5-3b). Knots and cross grain make lumber weaker than these clear samples (Handbook Chapter 5).
| Property | Green | 12% MC |
|---|---|---|
| Bending strength (MOR) | 6,100 psi (42 MPa) | 10,800 psi (74 MPa) |
| Stiffness (MOE) | 1,380,000 psi (9.5 GPa) | 1,610,000 psi (11.1 GPa) |
| Crushing strength (compression parallel to grain) | 2,840 psi (20 MPa) | 5,960 psi (41 MPa) |
| Compression perpendicular to grain | 240 psi (2 MPa) | 550 psi (4 MPa) |
| Shear parallel to grain | 740 psi (5 MPa) | 1,230 psi (8 MPa) |
| Tension perpendicular to grain | 100 psi (1 MPa) | — |
A dash means the Handbook prints no value; none is filled in.
Dust and health
- Wood dust is classed as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer, chiefly for cancers of the nose and sinuses.
- NIOSH recommends keeping wood dust exposure to 1 mg/m³ of total dust, as quoted in OSHA's sawmill guidance.
This is what the named authorities publish, not medical advice.
Compare with
Buying and finishing black spruce
Work it out for your project
- Rank woods for cabinets and trim with the species picker
Weigh black spruce against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
- Plan a finish for cabinets in black spruce
The finishes whose makers name that use, and a dated coat schedule from each product’s own sheet.
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured black spruce at 530 lbf of side hardness at 12% moisture content, on clear, straight-grained samples (Wood Handbook Table 5-3b).
One source: USDA Forest Products Laboratory, the authority for species properties it measured , sources [1]
What that means
Side hardness (Janka) is the load needed to press a 0.444 in (11.28 mm) steel ball halfway into the wood across the grain; a higher number dents less (Handbook p. 5-5).
One source: USDA Forest Products Laboratory, the authority for species properties it measured , sources [1]
So
Density at 12% is water's density × specific gravity × (1 + 0.12) (Handbook Eq. 4-14): 62.43 × 0.42 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 29 lb/ft³, or 2.4 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources