Wood species
Willow oak wood
Willow oak is a hardwood (Quercus phellos). At 12% moisture content it has a Janka hardness of 1,460 lbf (6,494 N) and it weighs about 48 lb/ft³ (773 kg/m³), 4 lb (1.82 kg) per board foot.
Also called: Quercus phellos.
Key numbers
- Janka hardness, 12% MC
- 1,460 lbf (6,494 N)
- Green: 980 lbf (4,359 N)
- Weight at 12% MC
- 48 lb/ft³ (773 kg/m³)
- 4 lb per board foot
- Specific gravity (oven-dry weight)
- 0.69 at 12% MC volume
- 0.56 on green volume
- Shrinkage, green to oven-dry
- 9.6% tangential
- Radial 5.0%, volumetric 18.9%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; willow oak's density is worked from its specific gravity with the Handbook's own equation.
How much willow oak moves
A 12 in wide flatsawn board of willow oak that goes from 6% to 12% moisture content swells about 0.25 in (about 1/4 in, 6.4 mm). Quartersawn, the same board moves about 0.11 in (about 1/8 in, 2.8 mm). Flatsawn faces move 1.9 times as much as quartersawn ones, because the wood shrinks 9.6% around the growth rings but only 5.0% across them.
Worked with the Wood Handbook's dimensional change coefficients for willow oak (the Handbook gives one row, "Red oak: water, laurel, willow", for the group) (Table 13-5: 0.00348 tangential, 0.00153 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
- Brown heartwood with a tinge of red; nearly white sapwood about 1 to 2 in. wide.
- Grain and texture
- Open pores without tyloses, and broad, conspicuous rays on quartersawn faces.
- Working and character
- Heavy, with fairly high shrinkage on drying; fast-grown second-growth wood is generally harder and tougher than old growth. The open pores make it unsuitable for tight barrels unless they are lined.
- Uses
- Red oak lumber goes into flooring, furniture, millwork, pallets, implements, caskets, wooden ware and handles.
The Handbook says sawn red oak lumber cannot be told apart by species, so this oak is sold as red oak; the table gives its own tested figures.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-9.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of willow oak 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) | 7,400 psi (51 MPa) | 14,500 psi (100 MPa) |
| Stiffness (MOE) | 1,290,000 psi (8.9 GPa) | 1,900,000 psi (13.1 GPa) |
| Crushing strength (compression parallel to grain) | 3,000 psi (21 MPa) | 7,040 psi (49 MPa) |
| Compression perpendicular to grain | 610 psi (4 MPa) | 1,130 psi (8 MPa) |
| Shear parallel to grain | 1,180 psi (8 MPa) | 1,650 psi (11 MPa) |
| Tension perpendicular to grain | 760 psi (5 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 willow oak
Work it out for your project
- Rank woods for furniture with the species picker
Weigh willow oak against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
- Plan a finish for furniture in willow oak
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 willow oak at 1,460 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 × 0.69 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 48 lb/ft³, or 4 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources