Wood species
Sapele wood
Sapele is a hardwood (Entandrophragma cylindricum). At 12% moisture content it has a Janka hardness of 1,510 lbf (6,717 N) and it weighs about 42 lb/ft³ (673 kg/m³), 3.5 lb (1.59 kg) per board foot.
Key numbers
- Janka hardness, 12% MC
- 1,510 lbf (6,717 N)
- Green: 1,020 lbf (4,537 N)
- Weight at 12% MC
- 42 lb/ft³ (673 kg/m³)
- 3.5 lb per board foot
- Specific gravity (oven-dry weight)
- 0.55 on green volume
- Shrinkage, green to oven-dry
- 7.4% tangential
- Radial 4.6%, volumetric 14.0%
One source: USDA Forest Products Laboratory, collected from the world literature (its Tables 5-5 and 4-4)
Why: From the USDA Wood Handbook, which collected these values from the world literature; sapele's density is worked from its specific gravity with the Handbook's own equations.
How much sapele moves
A 12 in wide flatsawn board of sapele that goes from 6% to 12% moisture content swells about 0.19 in (about 3/16 in, 4.8 mm). Quartersawn, the same board moves about 0.11 in (about 1/8 in, 2.9 mm). Flatsawn faces move 1.6 times as much as quartersawn ones, because the wood shrinks 7.4% around the growth rings but only 4.6% across them.
Worked from the Wood Handbook's shrinkage values (Table 4-4) with its Eq. 13-4; the Handbook gives no movement coefficients for imported woods. Individual boards vary: the Handbook gives shrinkage a coefficient of variation of about 15% (p. 4-11).
Color, grain and working
- Color
- From the color of American mahogany to dark reddish or purplish brown; lighter sapwood up to 4 in. wide.
- Grain and texture
- Rather fine texture; interlocked grain gives narrow, even stripes on quartersawn faces.
- Working and character
- Mechanical properties generally higher than white oak. Machines fairly easily, but the interlocked grain makes planing difficult; finishes and glues well. Moderately durable.
- Uses
- Furniture, cabinetwork, joinery, flooring and decorative plywood.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-36.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Values for sapele from Wood Handbook Table 5-5b (p. 5-24), which the Handbook says were collected from the world literature, on clear, straight-grained specimens. 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) | 15,300 psi (105 MPa) |
| Stiffness (MOE) | 1,490,000 psi (10.3 GPa) | 1,820,000 psi (12.5 GPa) |
| Crushing strength (compression parallel to grain) | 5,010 psi (35 MPa) | 8,160 psi (56 MPa) |
| Shear parallel to grain | 1,250 psi (9 MPa) | 2,260 psi (16 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 Wood Handbook prints 1,510 lbf of side hardness at 12% moisture content for sapele, a value it says was collected from the world literature (Table 5-5b, p. 5-24).
One source: USDA Forest Products Laboratory, collected from the world literature (its Tables 5-5 and 4-4) , 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, collected from the world literature (its Tables 5-5 and 4-4) , sources [1]
So
The Handbook gives only the green specific gravity (0.55) for sapele, so it is moved to 12% with the volumetric shrinkage of 14% (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 42 lb/ft³, or 3.5 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources