Wood species
Hard maple wood
Hard maple is a hardwood; this page covers the hard maple group, led by sugar maple (Acer saccharum). At 12% moisture content it has a Janka hardness of 1,450 lbf (6,450 N) and it weighs about 44 lb/ft³ (706 kg/m³), 3.7 lb (1.67 kg) per board foot.
Names and species on this page: sugar maple, rock maple, black maple.
Key numbers
- Janka hardness, 12% MC
- 1,450 lbf (6,450 N)
- Green: 970 lbf (4,315 N)
- Weight at 12% MC
- 44 lb/ft³ (706 kg/m³)
- 3.7 lb per board foot
- Specific gravity (oven-dry weight)
- 0.63 at 12% MC volume
- 0.56 on green volume
- Shrinkage, green to oven-dry
- 9.9% tangential
- Radial 4.8%, volumetric 14.7%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; hard maple's density is worked from its specific gravity with the Handbook's own equation.
How much hard maple moves
A 12 in wide flatsawn board of sugar maple that goes from 6% to 12% moisture content swells about 0.25 in (about 1/4 in, 6.5 mm). Quartersawn, the same board moves about 0.12 in (about 1/8 in, 3 mm). Flatsawn faces move 2.1 times as much as quartersawn ones, because the wood shrinks 9.9% around the growth rings but only 4.8% across them.
Worked with the Wood Handbook's dimensional change coefficients for sugar maple (Table 13-5: 0.00353 tangential, 0.00165 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 reddish-brown heartwood, sometimes much darker; white sapwood with a slight reddish tinge, usually 3 to 5 in. wide.
- Grain and texture
- Fine, uniform texture, generally straight; birdseye, curly and fiddleback figure is picked out for furniture.
- Working and character
- Heavy, strong, stiff, hard and tough, with high shrinkage.
- Uses
- Flooring, furniture, cabinets, cutting boards, pianos, billiard cues, bowling alleys, dance and gym floors.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-8.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of sugar maple 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) | 9,400 psi (65 MPa) | 15,800 psi (109 MPa) |
| Stiffness (MOE) | 1,550,000 psi (10.7 GPa) | 1,830,000 psi (12.6 GPa) |
| Crushing strength (compression parallel to grain) | 4,020 psi (28 MPa) | 7,830 psi (54 MPa) |
| Compression perpendicular to grain | 640 psi (4 MPa) | 1,470 psi (10 MPa) |
| Shear parallel to grain | 1,460 psi (10 MPa) | 2,330 psi (16 MPa) |
| Tension perpendicular to grain | — | — |
A dash means the Handbook prints no value; none is filled in.
The hard maple group
The Handbook tests each species separately; they are sold together as hard maple. Across the 2 species measured, Janka hardness at 12% runs from 1,180 to 1,450 lbf.
| Species | Janka, 12% MC | Weight, 12% MC | Tangential shrinkage |
|---|---|---|---|
| Sugar mapleAcer saccharum | 1,450 lbf | 44 lb/ft³ | 9.9% |
| Black mapleAcer nigrum | 1,180 lbf | 40 lb/ft³ | 9.3% |
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 sugar maple at 1,450 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 × 0.63 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 44 lb/ft³, or 3.7 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources