Wood species
Honeylocust wood
Honeylocust is a hardwood (Gleditsia triacanthos). At 12% moisture content it has a Janka hardness of 1,580 lbf (7,028 N) and it weighs about 45 lb/ft³ (719 kg/m³), 3.7 lb (1.7 kg) per board foot.
Also called: honey locust.
Key numbers
- Janka hardness, 12% MC
- 1,580 lbf (7,028 N)
- Green: 1,390 lbf (6,183 N)
- Weight at 12% MC
- 45 lb/ft³ (719 kg/m³)
- 3.7 lb per board foot
- Specific gravity (oven-dry weight)
- 0.60 on green volume
- Shrinkage, green to oven-dry
- 6.6% tangential
- Radial 4.2%, volumetric 10.8%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; honeylocust's density is worked from its specific gravity with the Handbook's own equation.
How much honeylocust moves
A 12 in wide flatsawn board of honeylocust 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 0.1 in (about 3/32 in, 2.6 mm). Flatsawn faces move 1.6 times as much as quartersawn ones, because the wood shrinks 6.6% around the growth rings but only 4.2% across them.
Worked with the Wood Handbook's dimensional change coefficients for honeylocust (Table 13-5: 0.0023 tangential, 0.00144 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
- Wide yellowish sapwood and light red to reddish-brown heartwood.
- Grain and texture
- Attractive figure.
- Working and character
- Heavy, hard, strong in bending, stiff and tough, and durable in contact with the ground.
- Uses
- Scarce, so used mostly locally for fence posts and general construction.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-7.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of honeylocust 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) | 10,200 psi (70 MPa) | 14,700 psi (101 MPa) |
| Stiffness (MOE) | 1,290,000 psi (8.9 GPa) | 1,630,000 psi (11.2 GPa) |
| Crushing strength (compression parallel to grain) | 4,420 psi (30 MPa) | 7,500 psi (52 MPa) |
| Compression perpendicular to grain | 1,150 psi (8 MPa) | 1,840 psi (13 MPa) |
| Shear parallel to grain | 1,660 psi (11 MPa) | 2,250 psi (16 MPa) |
| Tension perpendicular to grain | 930 psi (6 MPa) | 900 psi (6 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 honeylocust at 1,580 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
The Handbook gives only the green specific gravity (0.60) for honeylocust, so it is moved to 12% with the volumetric shrinkage of 10.8% (Eqs. 4-9 and 4-11), then multiplied by water's density and 1.12 (Eq. 4-14).
Arithmetic: exact by definition , sources [1]
The number
About 45 lb/ft³, or 3.7 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources