Water oak
Quercus nigra
Water oak measures 1,190 lbf on the Janka scale, 8% softer than northern red oak.
- Overcup oak has exactly the same Janka figure.
- Across all 155 woods it falls in the top fifth for face shrinkage, volumetric shrinkage and T/R ratio.
- On the Janka scale its nearest neighbours are black maple at 1,180 lbf and green ash at 1,200 lbf.
U.S. hardwoodsU.S. softwoodsImported woodsNorthern red oak
Six measures
Water oakU.S. hardwoods medianOther woods
Cupping tendency
2.2319th highest of 1551.092.90Shrinkage across the face
9.8%radial 4.4%25th highest of 1553.5%12.7%Stiffness
2.02 M psi13.9 GPa38th stiffest of 15526% above the U.S. hardwoods median0.54 M psi4.06 M psiBending strength
15,400 psi106.2 MPa46th strongest of 1554,300 psi29,900 psiDensity
0.560.63 at 12% MC52nd heaviest of 1550.250.96Janka hardness
1,190 lbf5,293 N63rd hardest of 15524th of 53 U.S. hardwoods240 lbf3,680 lbf
How much it moves
Most of its movement runs along the rings (T/R 2.23): quartersawn, the same board would lose 0.26 in. instead of 0.59 in.
0.59 in.
off a 6-inch flatsawn board, green to oven-dry
- Tangential
- 9.8%
- Radial
- 4.4%
- Volume
- 16.1%
- T/R ratio
- 2.23 (135th most stable of 155)
End view, shrinkage drawn 3× life size.
Closest substitutes
- Sugar maple
22% harder · same density · shrinks 0.1 points more across the face
- Willow oak
23% harder · same density · shrinks 0.2 points less across the face
- Pin oak
27% harder · 4% heavier · shrinks 0.3 points less across the face
Among the oaks
13th hardest of 15, lbf; the neighbours either side are shown, the rest are on the oaks page.
Laboratory values
Its most unusual laboratory figure is tension across the grain: 6th highest of the 73 woods with a published value.
| Property | Green | Dry, 12% MC | Change when dried | Metric, 12% MC |
|---|---|---|---|---|
| Tension perpendicular | 820psi | 920psi | +12% | 6.30MPa |
| Work to maximum load | 11.1in-lbf/in³ | 21.5in-lbf/in³ | +94% | 148.2kJ/m³ |
| Impact bending | 39in. | 44in. | +13% | 1,118mm |
| Compression perpendicular | 620psi | 1,020psi | +65% | 7.00MPa |
| Shear parallel to grain | 1,240psi | 2,020psi | +63% | 13.9MPa |
| Modulus of elasticity | 1.55M psi | 2.02M psi | +30% | 13.9GPa |
| Modulus of rupture | 8,900psi | 15,400psi | +73% | 106.2MPa |
| Side hardness | 1,010lbf | 1,190lbf | +18% | 5,293N |
| Compression parallel to grain | 3,740psi | 6,770psi | +81% | 46.7MPa |
Wood Handbook Table 5-3b, Table 4-3. Data & method · Guides