Wood species
Western white pine wood
Western white pine is a softwood (Pinus monticola). At 12% moisture content it has a Janka hardness of 420 lbf (1,868 N) and it weighs about 27 lb/ft³ (426 kg/m³), 2.2 lb (1 kg) per board foot.
Also called: Idaho white pine.
Key numbers
- Janka hardness, 12% MC
- 420 lbf (1,868 N)
- Green: 260 lbf (1,157 N)
- Weight at 12% MC
- 27 lb/ft³ (426 kg/m³)
- 2.2 lb per board foot
- Specific gravity (oven-dry weight)
- 0.38 at 12% MC volume
- 0.35 on green volume
- Shrinkage, green to oven-dry
- 7.4% tangential
- Radial 4.1%, volumetric 11.8%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; western white pine's density is worked from its specific gravity with the Handbook's own equation.
How much western white pine moves
A 12 in wide flatsawn board of western white pine that goes from 6% to 12% moisture content swells about 0.19 in (about 3/16 in, 4.7 mm). Quartersawn, the same board moves about 0.1 in (about 3/32 in, 2.6 mm). Flatsawn faces move 1.8 times as much as quartersawn ones, because the wood shrinks 7.4% around the growth rings but only 4.1% across them.
Worked with the Wood Handbook's dimensional change coefficients for western white pine (Table 13-5: 0.00259 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
- Cream to light reddish-brown heartwood that darkens in air; yellowish-white sapwood.
- Grain and texture
- Straight.
- Working and character
- Moderately light, soft and fairly weak, with fairly high shrinkage, but easy to work, easy to kiln-dry and stable afterwards.
- Uses
- Patterns, millwork, siding, sashes, door frames and knotty paneling; much the same uses as eastern white and sugar pine.
The Handbook reports that white pine blister rust, an introduced fungus, has led the IUCN to list western white pine as near threatened.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-16.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of western white pine 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) | 4,700 psi (32 MPa) | 9,700 psi (67 MPa) |
| Stiffness (MOE) | 1,190,000 psi (8.2 GPa) | 1,460,000 psi (10.1 GPa) |
| Crushing strength (compression parallel to grain) | 2,430 psi (17 MPa) | 5,040 psi (35 MPa) |
| Compression perpendicular to grain | 190 psi (1 MPa) | 470 psi (3 MPa) |
| Shear parallel to grain | 680 psi (5 MPa) | 1,040 psi (7 MPa) |
| Tension perpendicular to grain | 260 psi (2 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
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured western white pine at 420 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 × 0.38 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 27 lb/ft³, or 2.2 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources