Wood species
Pecan wood
Pecan is a hardwood; this page covers the pecan hickory group, led by pecan hickory (Carya illinoensis). At 12% moisture content it has a Janka hardness of 1,820 lbf (8,096 N) and it weighs about 46 lb/ft³ (739 kg/m³), 3.8 lb (1.74 kg) per board foot.
Names and species on this page: pecan hickory, bitternut hickory, water hickory, nutmeg hickory.
Key numbers
- Janka hardness, 12% MC
- 1,820 lbf (8,096 N)
- Green: 1,310 lbf (5,827 N)
- Weight at 12% MC
- 46 lb/ft³ (739 kg/m³)
- 3.8 lb per board foot
- Specific gravity (oven-dry weight)
- 0.66 at 12% MC volume
- 0.60 on green volume
- Shrinkage, green to oven-dry
- 8.9% tangential
- Radial 4.9%, volumetric 13.6%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; pecan's density is worked from its specific gravity with the Handbook's own equation.
How much pecan moves
A 12 in wide flatsawn board of pecan hickory that goes from 6% to 12% moisture content swells about 0.23 in (about 7/32 in, 5.8 mm). Quartersawn, the same board moves about 0.12 in (about 1/8 in, 3.1 mm). Flatsawn faces move 1.8 times as much as quartersawn ones, because the wood shrinks 8.9% around the growth rings but only 4.9% across them.
Worked with the Wood Handbook's dimensional change coefficients for pecan hickory (the Handbook gives one row, "Hickory, pecan", for the group) (Table 13-5: 0.00315 tangential, 0.00169 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 white or nearly white sapwood and somewhat darker heartwood.
- Working and character
- Heavy, and sometimes very high in shrinkage.
- Uses
- Tool and implement handles and flooring; higher grades are sliced for furniture and paneling veneer, lower grades go to pallets.
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 pecan hickory 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) | 9,800 psi (68 MPa) | 13,700 psi (94 MPa) |
| Stiffness (MOE) | 1,370,000 psi (9.4 GPa) | 1,730,000 psi (11.9 GPa) |
| Crushing strength (compression parallel to grain) | 3,990 psi (28 MPa) | 7,850 psi (54 MPa) |
| Compression perpendicular to grain | 780 psi (5 MPa) | 1,720 psi (12 MPa) |
| Shear parallel to grain | 1,480 psi (10 MPa) | 2,080 psi (14 MPa) |
| Tension perpendicular to grain | 680 psi (5 MPa) | — |
A dash means the Handbook prints no value; none is filled in.
The pecan hickory group
The Handbook tests each species separately; they are sold together as pecan. Across the 1 species measured, Janka hardness at 12% runs from 1,820 to 1,820 lbf.
| Species | Janka, 12% MC | Weight, 12% MC | Tangential shrinkage |
|---|---|---|---|
| Pecan hickoryCarya illinoensis | 1,820 lbf | 46 lb/ft³ | 8.9% (pecan hickory group) |
| Bitternut hickoryCarya cordiformis | — | 46 lb/ft³ | 8.9% (pecan hickory group) |
| Water hickoryCarya aquatica | — | 43 lb/ft³ | 8.9% (pecan hickory group) |
| Nutmeg hickoryCarya myristiciformis | — | 42 lb/ft³ | 8.9% (pecan hickory group) |
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 pecan hickory at 1,820 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 × 0.66 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 46 lb/ft³, or 3.8 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources