Wood species
Lignum vitae wood
Lignum vitae is a hardwood (Guaiacum spp.). At 12% moisture content it has a Janka hardness of 4,500 lbf (20,017 N) and it weighs about 88 lb/ft³ (1,412 kg/m³), 7.3 lb (3.33 kg) per board foot.
Also called: lignumvitae.
Key numbers
- Janka hardness, 12% MC
- 4,500 lbf (20,017 N)
- Weight at 12% MC
- 88 lb/ft³ (1,412 kg/m³)
- Handbook estimate (Eq. 4-13): no shrinkage is published
- 7.3 lb per board foot
- Specific gravity (oven-dry weight)
- 1.05 on green volume
- Shrinkage, green to oven-dry
- Not measured tangential
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; lignum vitae's density is worked from its specific gravity with the Handbook's own equations.
How much lignum vitae moves
The 2021 Wood Handbook prints no shrinkage or movement coefficient for lignumvitae, so this page gives no movement figure rather than borrow one from another species.
Color, grain and working
- Color
- A distinctive green.
- Grain and texture
- Fine, uniform texture and closely interlocked grain, with an oily or waxy feel.
- Working and character
- One of the heaviest and hardest woods on the market; resins can be a quarter of the dry weight, which makes it self-lubricating.
- Uses
- Bearing blocks for ship propeller shafts, mallets, pulley sheaves, caster wheels and turned goods.
The Handbook reports both commercial Guaiacum species are listed in CITES Appendix II.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-28.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Values for lignumvitae 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) | — | — |
| Stiffness (MOE) | — | — |
| Crushing strength (compression parallel to grain) | — | 11,400 psi (79 MPa) |
| Shear parallel to grain | — | — |
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 4,500 lbf of side hardness at 12% moisture content for lignumvitae, 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 (1.05) for lignumvitae, so it is moved to 12% with the volumetric shrinkage of undefined% (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 88 lb/ft³, or 7.3 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources