Wood species
Tupelo wood
Tupelo is a hardwood; this page covers the tupelo, led by black tupelo (Nyssa sylvatica). At 12% moisture content it has a Janka hardness of 810 lbf (3,603 N) and it weighs about 35 lb/ft³ (560 kg/m³), 2.9 lb (1.32 kg) per board foot.
Names and species on this page: black tupelo, blackgum, water tupelo, tupelo gum, sourgum.
Key numbers
- Janka hardness, 12% MC
- 810 lbf (3,603 N)
- Green: 640 lbf (2,847 N)
- Weight at 12% MC
- 35 lb/ft³ (560 kg/m³)
- 2.9 lb per board foot
- Specific gravity (oven-dry weight)
- 0.50 at 12% MC volume
- 0.46 on green volume
- Shrinkage, green to oven-dry
- 8.7% tangential
- Radial 5.1%, volumetric 14.4%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; tupelo's density is worked from its specific gravity with the Handbook's own equation.
How much tupelo moves
A 12 in wide flatsawn board of black tupelo that goes from 6% to 12% moisture content swells about 0.22 in (about 7/32 in, 5.6 mm). Quartersawn, the same board moves about 0.13 in (about 1/8 in, 3.2 mm). Flatsawn faces move 1.7 times as much as quartersawn ones, because the wood shrinks 8.7% around the growth rings but only 5.1% across them.
Worked with the Wood Handbook's dimensional change coefficients for black tupelo (Table 13-5: 0.00308 tangential, 0.00176 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 brownish-gray heartwood blending into wide, lighter sapwood.
- Grain and texture
- Fine, uniform texture with interlocked grain.
- Working and character
- Moderately heavy, strong, hard and stiff. The interlocked grain calls for care in drying, and wood from swamp-grown buttresses is much lighter.
- Uses
- Boxes, pallets, crates, baskets, furniture and veneer.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-10.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of black tupelo 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) | 7,000 psi (48 MPa) | 9,600 psi (66 MPa) |
| Stiffness (MOE) | 1,030,000 psi (7.1 GPa) | 1,200,000 psi (8.3 GPa) |
| Crushing strength (compression parallel to grain) | 3,040 psi (21 MPa) | 5,520 psi (38 MPa) |
| Compression perpendicular to grain | 480 psi (3 MPa) | 930 psi (6 MPa) |
| Shear parallel to grain | 1,100 psi (8 MPa) | 1,340 psi (9 MPa) |
| Tension perpendicular to grain | 570 psi (4 MPa) | 500 psi (3 MPa) |
A dash means the Handbook prints no value; none is filled in.
The tupelo
The Handbook tests each species separately; they are sold together as tupelo. Across the 2 species measured, Janka hardness at 12% runs from 810 to 880 lbf.
| Species | Janka, 12% MC | Weight, 12% MC | Tangential shrinkage |
|---|---|---|---|
| Black tupeloNyssa sylvatica | 810 lbf | 35 lb/ft³ | 8.7% |
| Water tupeloNyssa aquatica | 880 lbf | 35 lb/ft³ | 7.6% |
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 black tupelo at 810 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 × 0.50 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 35 lb/ft³, or 2.9 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources