Cumaru VS African Blackwood
- Leads on stiffness, lightness, machining ease — a narrow but consistent edge
- Close second across most categories
- Solid choice where its profile fits the project
Visual comparison
Winner by category
There isn't one universally best wood — there's a best wood for each purpose.
| Category | Winner |
|---|---|
| Durability | Tie |
| Stability | Tie |
| Hardness | Tie |
| Strength (MOR) | African Blackwood |
| Stiffness (MOE) | Cumaru |
| Flame spread | Tie |
| Machining ease | Tie |
| Lightness | Cumaru |
Engineering data
| Property | Cumaru | African Blackwood |
|---|---|---|
| Janka Hardness | 3330WD lbf | 3670WD lbf |
| Density | 0.87WD g/cm³ | 0.98WD g/cm³ |
| MOE | 22.33WD GPa | 17.95WD GPa |
| MOR | 175.1WD MPa | 213.0WD MPa |
| Durability | Class 1 Very Durable | Class 1 Very Durable |
| Stability | Excellent | Excellent |
| Fire (E84) | Class A indicative | Class A indicative |
| Radial Shrink | 5.3WD % | 2.9WD % |
| Tangential Shrink | 7.7WD % | 4.8WD % |
| T/R Ratio | 1.45 | 1.66 |
Figures carry the same source status as the species pages they come from — verified where cited, indicative where marked.
Best for
| Application | Recommended | Suitability |
|---|---|---|
| Outdoor decking / pergola | 🥇 Cumaru | ★★★★★ |
| Exterior cladding | 🥇 Cumaru | ★★★★☆ |
| Flooring / wear surfaces | 🥇 African Blackwood | ★★★★★ |
| Furniture / interior joinery | 🥇 Cumaru | ★★☆☆☆ |
| Structural / load-bearing | 🥇 Cumaru | ★★★★★ |
Advantages & limitations
Cumaru
Advantages relative to African Blackwood
- MOE is 22.3 GPa vs 17.9 GPa, about 25% higher
Limitations relative to African Blackwood
- MOR is 175.1 MPa vs 213 MPa, about 18% lower
African Blackwood
Advantages relative to Cumaru
- MOR is 213 MPa vs 175.1 MPa, about 22% higher
Limitations relative to Cumaru
- MOE is 17.9 GPa vs 22.3 GPa, about 20% lower
Recommendation
Choose Cumaru if…
- Decking, boardwalks, marine structures and heavy exterior joinery where the higher stiffness is what the span or loading demands and the shared Class 1 durability and Class A fire class are the baseline
- Structural components subject to bending loads where the working stiffness advantage matters in specification
Choose African Blackwood if…
- Woodwind instruments (the species page documents clarinets, oboes, flutes and bagpipes), guitar backs and fingerboards, fine turnery and decorative inlay where the higher bending strength and shared Class 1 durability are what the piece needs
- Small structural components where extreme hardness and bending strength both matter in specification
Frequently asked questions
Which is more durable, Cumaru or African Blackwood?
Neither — both carry the same EN 350 rating (Class 1, Very Durable). For outdoor work the separation is movement, not decay: African Blackwood moves 4.8% tangentially against 7.7%, which decides board width and fixing spacing more than the durability class does.
Which wood is better for outdoor use?
Both are EN 350 Class 1, and tangential movement runs 7.7% for Cumaru against 4.8% for African Blackwood — close enough that decay resistance will not choose between them, and African Blackwood holds its dimension marginally better. African Blackwood gives the harder wearing surface at 3,670 lbf; Cumaru is the lighter section at 0.87 g/cm³ — traffic favours the first, cladding and handling the second.
Is Cumaru harder than African Blackwood?
No — African Blackwood is harder (Janka 3670 vs 3330 lbf).