Wood species
Jack pine wood
Jack pine is a softwood (Pinus banksiana). At 12% moisture content it has a Janka hardness of 570 lbf (2,535 N) and it weighs about 30 lb/ft³ (482 kg/m³), 2.5 lb (1.14 kg) per board foot.
Also called: scrub pine, gray pine, Pinus banksiana.
Key numbers
- Janka hardness, 12% MC
- 570 lbf (2,535 N)
- Green: 400 lbf (1,779 N)
- Weight at 12% MC
- 30 lb/ft³ (482 kg/m³)
- 2.5 lb per board foot
- Specific gravity (oven-dry weight)
- 0.43 at 12% MC volume
- 0.40 on green volume
- Shrinkage, green to oven-dry
- 6.6% tangential
- Radial 3.7%, volumetric 10.3%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; jack pine's density is worked from its specific gravity with the Handbook's own equation.
How much jack pine moves
A 12 in wide flatsawn board of jack pine that goes from 6% to 12% moisture content swells about 0.17 in (about 5/32 in, 4.2 mm). Quartersawn, the same board moves about 0.09 in (about 3/32 in, 2.3 mm). Flatsawn faces move 1.8 times as much as quartersawn ones, because the wood shrinks 6.6% around the growth rings but only 3.7% across them.
Worked with the Wood Handbook's dimensional change coefficients for jack pine (Table 13-5: 0.0023 tangential, 0.00126 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 brown to orange heartwood; nearly white sapwood that can be half the tree or more.
- Grain and texture
- Rather coarse and somewhat resinous; the lumber is generally knotty.
- Working and character
- Moderately light, moderately low in bending and compressive strength and in shock resistance, low in stiffness, with moderately low shrinkage.
- Uses
- Pulpwood, box lumber and pallets; also crossties, mine timber, poles, posts and fuel.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-14.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of jack 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) | 6,000 psi (41 MPa) | 9,900 psi (68 MPa) |
| Stiffness (MOE) | 1,070,000 psi (7.4 GPa) | 1,350,000 psi (9.3 GPa) |
| Crushing strength (compression parallel to grain) | 2,950 psi (20 MPa) | 5,660 psi (39 MPa) |
| Compression perpendicular to grain | 300 psi (2 MPa) | 580 psi (4 MPa) |
| Shear parallel to grain | 750 psi (5 MPa) | 1,170 psi (8 MPa) |
| Tension perpendicular to grain | 360 psi (2 MPa) | 420 psi (3 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 jack pine
Work it out for your project
- Rank woods for ground contact with the species picker
Weigh jack pine against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured jack pine at 570 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 × 0.43 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 30 lb/ft³, or 2.5 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources