Wood species
Butternut wood
Butternut is a hardwood (Juglans cinerea). At 12% moisture content it has a Janka hardness of 490 lbf (2,180 N) and it weighs about 27 lb/ft³ (426 kg/m³), 2.2 lb (1 kg) per board foot.
Also called: white walnut.
Key numbers
- Janka hardness, 12% MC
- 490 lbf (2,180 N)
- Green: 390 lbf (1,735 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
- 0.36 on green volume
- Shrinkage, green to oven-dry
- 6.4% tangential
- Radial 3.4%, volumetric 10.6%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; butternut's density is worked from its specific gravity with the Handbook's own equation.
How much butternut moves
A 12 in wide flatsawn board of butternut that goes from 6% to 12% moisture content swells about 0.16 in (about 5/32 in, 4.1 mm). Quartersawn, the same board moves about 0.08 in (about 3/32 in, 2.1 mm). Flatsawn faces move 1.9 times as much as quartersawn ones, because the wood shrinks 6.4% around the growth rings but only 3.4% across them.
Worked with the Wood Handbook's dimensional change coefficients for butternut (Table 13-5: 0.00223 tangential, 0.00116 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 heartwood, often with pinkish tones or darker brown streaks, and narrow, nearly white sapwood.
- Grain and texture
- Rather coarse texture.
- Working and character
- Moderately light and soft, low in stiffness, but it machines easily and finishes well. Stained, it looks much like black walnut without walnut’s strength or hardness.
- Uses
- Furniture, cabinets, paneling and interior woodwork.
The Handbook reports that butternut canker, a fungal disease first described in 1979, is killing butternut widely, and the IUCN lists it as endangered.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-5.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of butternut 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) | 5,400 psi (37 MPa) | 8,100 psi (56 MPa) |
| Stiffness (MOE) | 970,000 psi (6.7 GPa) | 1,180,000 psi (8.1 GPa) |
| Crushing strength (compression parallel to grain) | 2,420 psi (17 MPa) | 5,110 psi (35 MPa) |
| Compression perpendicular to grain | 220 psi (2 MPa) | 460 psi (3 MPa) |
| Shear parallel to grain | 760 psi (5 MPa) | 1,170 psi (8 MPa) |
| Tension perpendicular to grain | 430 psi (3 MPa) | 440 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 butternut at 490 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