Wood species
Port Orford cedar wood
Port Orford cedar is a softwood (Chamaecyparis lawsoniana). At 12% moisture content it has a Janka hardness of 630 lbf (2,802 N) and it weighs about 30 lb/ft³ (482 kg/m³), 2.5 lb (1.14 kg) per board foot.
Also called: Port-Orford-cedar, Lawson cypress, Oregon cedar.
Key numbers
- Janka hardness, 12% MC
- 630 lbf (2,802 N)
- Green: 380 lbf (1,690 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
- 0.39 on green volume
- Shrinkage, green to oven-dry
- 6.9% tangential
- Radial 4.6%, volumetric 10.1%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; Port Orford cedar's density is worked from its specific gravity with the Handbook's own equation.
How much Port Orford cedar moves
A 12 in wide flatsawn board of Port-Orford-cedar that goes from 6% to 12% moisture content swells about 0.17 in (about 3/16 in, 4.4 mm). Quartersawn, the same board moves about 0.11 in (about 1/8 in, 2.9 mm). Flatsawn faces move 1.5 times as much as quartersawn ones, because the wood shrinks 6.9% around the growth rings but only 4.6% across them.
Worked with the Wood Handbook's dimensional change coefficients for Port-Orford-cedar (Table 13-5: 0.00241 tangential, 0.00158 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 yellow to pale brown heartwood; narrow sapwood that is hard to tell apart.
- Grain and texture
- Fine, generally straight, with a pleasant spicy smell.
- Working and character
- Moderately light, stiff, moderately strong and hard; highly decay resistant, little tendency to warp, stable once dry.
- Uses
- Archery supplies, sash and door work, flooring, interior woodwork, furniture and boats.
The Handbook reports that a non-native root disease kills Port-Orford-cedar and the IUCN lists it as near threatened.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-16 to 2-17.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of Port-Orford-cedar 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) | 6,600 psi (46 MPa) | 12,700 psi (88 MPa) |
| Stiffness (MOE) | 1,300,000 psi (9 GPa) | 1,700,000 psi (11.7 GPa) |
| Crushing strength (compression parallel to grain) | 3,140 psi (22 MPa) | 6,250 psi (43 MPa) |
| Compression perpendicular to grain | 300 psi (2 MPa) | 720 psi (5 MPa) |
| Shear parallel to grain | 840 psi (6 MPa) | 1,370 psi (9 MPa) |
| Tension perpendicular to grain | 180 psi (1 MPa) | 400 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
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured Port-Orford-cedar at 630 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