Kapur
Dryobalanops spp.
Kapur measures 1,230 lbf on the Janka scale, 5% softer than northern red oak.
- Only five woods sit further below the density–hardness trend: a specific gravity of 0.64 would point to about 1,710 lbf.
- Across all 155 woods it falls in the top fifth for density, bending strength, face shrinkage and T/R ratio.
- On the Janka scale its nearest neighbours are laurel oak at 1,210 lbf and Caribbean pine at 1,240 lbf.
U.S. hardwoodsU.S. softwoodsImported woodsNorthern red oak
Six measures
KapurImported woods medianOther woods
Shrinkage across the face
10.2%radial 4.6%21st highest of 15529% above the imported woods median3.5%12.7%Cupping tendency
2.2222nd highest of 15528% above the imported woods median1.092.90Bending strength
18,300 psi126.2 MPa26th strongest of 1554,300 psi29,900 psiDensity
0.6431st heaviest of 1550.250.96Stiffness
1.88 M psi13.0 GPa49th stiffest of 1550.54 M psi4.06 M psiJanka hardness
1,230 lbf5,471 N59th hardest of 15539th of 65 imported woods240 lbf3,680 lbf
How much it moves
Most of its movement runs along the rings (T/R 2.22): quartersawn, the same board would lose 0.28 in. instead of 0.61 in.
0.61 in.
off a 6-inch flatsawn board, green to oven-dry
- Tangential
- 10.2%
- Radial
- 4.6%
- Volume
- 14.8%
- T/R ratio
- 2.22 (134th most stable of 155)
End view, shrinkage drawn 3× life size.
Closest substitutes
- Scarlet oak
14% harder · 6% lighter · shrinks 0.6 points more across the face
- Sugar maple
18% harder · 12% lighter · shrinks 0.3 points less across the face
- Keruing
3% harder · 8% heavier · shrinks 0.7 points more across the face
Woods of similar hardness
The eight nearest on the Janka scale, lbf.
Laboratory values
| Property | Green | Dry, 12% MC | Change when dried | Metric, 12% MC |
|---|---|---|---|---|
| Work to maximum load | 15.7in-lbf/in³ | 18.8in-lbf/in³ | +20% | 129.6kJ/m³ |
| Compression parallel to grain | 6,220psi | 10,090psi | +62% | 69.6MPa |
| Modulus of rupture | 12,800psi | 18,300psi | +43% | 126.2MPa |
| Shear parallel to grain | 1,170psi | 1,990psi | +70% | 13.7MPa |
| Modulus of elasticity | 1.60M psi | 1.88M psi | +17% | 13.0GPa |
| Side hardness | 980lbf | 1,230lbf | +26% | 5,471N |
Wood Handbook Table 5-5b, Table 4-4. Data & method · Guides