Wood species
Black oak wood
Black oak is a hardwood (Quercus velutina). At 12% moisture content it has a Janka hardness of 1,210 lbf (5,382 N) and it weighs about 43 lb/ft³ (683 kg/m³), 3.6 lb (1.61 kg) per board foot.
Also called: Quercus velutina.
Key numbers
- Janka hardness, 12% MC
- 1,210 lbf (5,382 N)
- Green: 1,060 lbf (4,715 N)
- Weight at 12% MC
- 43 lb/ft³ (683 kg/m³)
- 3.6 lb per board foot
- Specific gravity (oven-dry weight)
- 0.61 at 12% MC volume
- 0.56 on green volume
- Shrinkage, green to oven-dry
- 11.1% tangential
- Radial 4.4%, volumetric 15.1%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; black oak's density is worked from its specific gravity with the Handbook's own equation.
How much black oak moves
A 12 in wide flatsawn board of black oak that goes from 6% to 12% moisture content swells about 0.29 in (about 9/32 in, 7.3 mm). Quartersawn, the same board moves about 0.11 in (about 3/32 in, 2.8 mm). Flatsawn faces move 2.5 times as much as quartersawn ones, because the wood shrinks 11.1% around the growth rings but only 4.4% across them.
Worked with the Wood Handbook's dimensional change coefficients for black oak (Table 13-5: 0.004 tangential, 0.00151 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 black 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) | 8,200 psi (57 MPa) | 13,900 psi (96 MPa) |
| Stiffness (MOE) | 1,180,000 psi (8.1 GPa) | 1,640,000 psi (11.3 GPa) |
| Crushing strength (compression parallel to grain) | 3,470 psi (24 MPa) | 6,520 psi (45 MPa) |
| Compression perpendicular to grain | 710 psi (5 MPa) | 930 psi (6 MPa) |
| Shear parallel to grain | 1,220 psi (8 MPa) | 1,910 psi (13 MPa) |
| Tension perpendicular to grain | — | — |
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 oak
Work it out for your project
- Rank woods for furniture with the species picker
Weigh black oak against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
- Plan a finish for furniture in black 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 black oak at 1,210 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 × 0.61 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 43 lb/ft³, or 3.6 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources