Wood species
Mahogany wood
Mahogany is a hardwood (Swietenia macrophylla). At 12% moisture content it has a Janka hardness of 800 lbf (3,559 N) and it weighs about 33 lb/ft³ (529 kg/m³), 2.8 lb (1.25 kg) per board foot.
Also called: true mahogany, American mahogany, Honduras mahogany.
Key numbers
- Janka hardness, 12% MC
- 800 lbf (3,559 N)
- Green: 740 lbf (3,292 N)
- Weight at 12% MC
- 33 lb/ft³ (529 kg/m³)
- 2.8 lb per board foot
- Specific gravity (oven-dry weight)
- 0.45 on green volume
- Shrinkage, green to oven-dry
- 4.1% tangential
- Radial 3.0%, volumetric 7.8%
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; mahogany's density is worked from its specific gravity with the Handbook's own equations.
How much mahogany moves
A 12 in wide flatsawn board of true mahogany that goes from 6% to 12% moisture content swells about 0.1 in (about 3/32 in, 2.6 mm). Quartersawn, the same board moves about 0.07 in (about 1/16 in, 1.9 mm). Flatsawn faces move 1.4 times as much as quartersawn ones, because the wood shrinks 4.1% around the growth rings but only 3.0% 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
- Pale pink or salmon to dark reddish brown.
- Grain and texture
- Generally straighter than African mahogany, with many figure patterns; rather fine to coarse texture.
- Working and character
- Dries easily without warping or checking and is very stable. Very easy to work by hand or machine, slices into fine veneer, finishes easily and takes an excellent polish. Durable against decay; strength about like American elm.
- Uses
- Fine furniture and cabinets, interior woodwork, patterns, boats, musical instruments, paneling, turning and carving.
The Handbook explains that “mahogany” covers three woods: this one (Swietenia), African mahogany (Khaya), and “Philippine mahogany”, which is meranti (Shorea). Swietenia macrophylla is listed in CITES Appendix II.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-29.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Values for true mahogany from Wood Handbook Table 5-5b (p. 5-23), 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) | 9,000 psi (62 MPa) | 11,500 psi (79 MPa) |
| Stiffness (MOE) | 1,340,000 psi (9.2 GPa) | 1,500,000 psi (10.3 GPa) |
| Crushing strength (compression parallel to grain) | 4,340 psi (30 MPa) | 6,780 psi (47 MPa) |
| Shear parallel to grain | 1,240 psi (9 MPa) | 1,230 psi (8 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 800 lbf of side hardness at 12% moisture content for true mahogany, a value it says was collected from the world literature (Table 5-5b, p. 5-23).
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 (0.45) for true mahogany, so it is moved to 12% with the volumetric shrinkage of 7.8% (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 33 lb/ft³, or 2.8 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources