Wood species
Rubberwood wood
Rubberwood is a hardwood (Hevea brasiliensis). The Wood Handbook publishes no hardness or strength for it, only its shrinkage.
Key numbers
- Janka hardness, 12% MC
- Not published
- Weight at 12% MC
- Not published
- Specific gravity (oven-dry weight)
- Not published
- Shrinkage, green to oven-dry
- 5.1% tangential
- Radial 2.3%, volumetric 7.4%
One source: USDA Forest Products Laboratory, collected from the world literature (its Tables 5-5 and 4-4)
Why: The Wood Handbook gives rubberwood's shrinkage but no hardness or strength.
How much rubberwood moves
A 12 in wide flatsawn board of rubberwood that goes from 6% to 12% moisture content swells about 0.13 in (about 1/8 in, 3.2 mm). Quartersawn, the same board moves about 0.06 in (about 1/16 in, 1.4 mm). Flatsawn faces move 2.2 times as much as quartersawn ones, because the wood shrinks 5.1% around the growth rings but only 2.3% 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
The Wood Handbook lists rubberwood only in its imported-woods shrinkage table and does not describe its color, working or uses, so this page doesn't either.
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 publishes no hardness or strength for rubberwood; it lists only its shrinkage (Table 4-4), so none is given here.
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]
Sources