Balsa

Family

Wood

Category

wood

Species

Ochroma pyramidale

Density

0.16 g/cm³ · 160 kg/m³

Species measured

Balsa (Ochroma pyramidale)

Specific gravity

0.16

Modulus of rupture

3,140 psi · 21.6 MPa

Modulus of elasticity

0.49 ×10⁶ psi · 3.38 GPa

Table 5–5b carries no side hardness figure for balsa, so none is given here.

Source: USDA Forest Service, Wood Handbook — Wood as an Engineering Material (FPL-GTR-190, 2010), Table 5–5b, for clear straight-grained specimens at 12% moisture content. The grey figures are converted at 1 lbf = 4.448 N, 1 psi = 6.895 kPa and 1 GPa = 145,038 psi; the inch-pound numbers are the published ones. Specific gravity is oven-dry mass over volume at 12% moisture content, so it sits about 12% below the working density at the top of this page (0.16 × 1.12 ≈ 0.18 g/cm³). The two come from different sampling programmes, so a few species differ by more than that.

Origin

Central and South America

Appearance

Very pale, almost white, with a coarse open texture

Working

Cut with a sharp blade and sand lightly — it dents under a clamp and crushes if handled roughly.

Unlike the USDA figures above, these lines are not measurements: they carry no units and no single source. They describe how the timber is generally found to behave rather than what it is guaranteed to do — read them as the consensus of the trade, not as a specification.

• Density is for air-dried stock at about 12% moisture content
• Very wide density spread — model grade and structural grade differ greatly
• Hardwood by botanical grouping despite being far softer than pine

Dressed sizes are the same for every species — a 2x4 is 1-1/2 x 3-1/2 in in oak as much as in spruce. What changes is the weight, and that is derived here from balsa's density of 0.16 g/cm³.

Which tools work a material is a property of the family (Wood), not of the individual species — so this list is the same on every wood page, and changes when the tool data changes rather than when this paragraph does.