Wood species
Peroba rosa wood
Peroba rosa is a hardwood (Aspidosperma spp., peroba group). At 12% moisture content it has a Janka hardness of 1,730 lbf (7,695 N) and it weighs about 50 lb/ft³ (795 kg/m³), 4.1 lb (1.87 kg) per board foot.
Also called: peroba.
Key numbers
- Janka hardness, 12% MC
- 1,730 lbf (7,695 N)
- Green: 1,580 lbf (7,028 N)
- Weight at 12% MC
- 50 lb/ft³ (795 kg/m³)
- 4.1 lb per board foot
- Specific gravity (oven-dry weight)
- 0.66 on green volume
- Shrinkage, green to oven-dry
- 6.4% tangential
- Radial 3.8%, volumetric 11.6%
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; peroba rosa's density is worked from its specific gravity with the Handbook's own equations.
How much peroba rosa moves
A 12 in wide flatsawn board of peroba rosa that goes from 6% to 12% moisture content swells about 0.16 in (about 5/32 in, 4.1 mm). Quartersawn, the same board moves about 0.09 in (about 3/32 in, 2.4 mm). Flatsawn faces move 1.7 times as much as quartersawn ones, because the wood shrinks 6.4% around the growth rings but only 3.8% 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
- Rose-red to yellowish, sometimes with purple or brown streaks, turning brownish yellow to dark brown.
- Grain and texture
- Fine, uniform texture; straight to irregular grain.
- Working and character
- Moderately heavy, with strength comparable with US oaks. Dries with little checking, works with moderate ease, glues and finishes well; resists decay but not dry-wood termites.
- Uses
- Fine furniture, cabinetwork and decorative veneer; flooring, interior woodwork, sashes, doors and turnery.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-33.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Values for peroba rosa 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) | 10,900 psi (75 MPa) | 12,100 psi (83 MPa) |
| Stiffness (MOE) | 1,290,000 psi (8.9 GPa) | 1,530,000 psi (10.5 GPa) |
| Crushing strength (compression parallel to grain) | 5,540 psi (38 MPa) | 7,920 psi (55 MPa) |
| Shear parallel to grain | 1,880 psi (13 MPa) | 2,490 psi (17 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 1,730 lbf of side hardness at 12% moisture content for peroba rosa, 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 (0.66) for peroba rosa, so it is moved to 12% with the volumetric shrinkage of 11.6% (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 50 lb/ft³, or 4.1 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources