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Blackwood African
(Dalbergia
melanoxylon)
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| Common
Names: |
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African
blackwood
African ebony
African grenadilo
Banbanus
Ebene
Grenadilla
Grenadille d'Afrique
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Mpingo
Mufunjo
Mugembe
Mukelete
Pau preto
Poyi
Zebra wood
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- Mechanical Values
| Category |
Green |
Dry |
Units |
| Weight |
87 |
75 |
lbs/cu.ft. |
| Density
(air-dry) |
|
78 |
lbs/cu.ft. |
| Specific
Gravity |
|
1 |
|
| Hardness |
|
|
|
| Stiffness |
2276 |
|
1000
psi |
| Bending
Strength |
|
31640 |
psi |
| Shearing
Strength |
|
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| Max.
Crushing Strength |
|
10800 |
psi |
| Work to
Maximum Load |
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| Radial
Shrinkage (G->OD) |
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| Tangential
Shrink. (G->OD) |
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| Volumetric
Shrink (G->OD) |
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- Environmental
Profile
- The environmental
status of this species within its natural habitat
has not been officially determined.
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- Distribution
- African blackwood is
reported to occur extensively in the savannah areas
in Africa, from Sudan southward to Mozambique,
westward to Angola, and northward to Nigeria and
Senegal. The
tree is also reported to grow in western India.
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- Product Sources
- Some material from
this species is reported to be available from
sustainably managed or other environmentally
responsible sources.
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- The International
Tropical Timber Organization (ITTO) reports that
timber from this species is produced in limited
volumes and is exported in small sized cants.
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- The timber is
reported to be exported in log form from East
African ports.
Log lengths are usually from 3 to 5 feet (0.9
to 1.5 m) and are often sold by importers only in
log form and by the pound.
Price range is reported to be in the
expensive range.
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- Tree Data
- The small tree is
reported to often develop more than a single stem.
It usually grows to a height of 15 to 20 feet
(4.5 to 6 m), but may occasionally reach 50 feet (15
m). The
bole is often short, fluted, and rarely cylindrical,
with diameters that are seldom more than 12 inches
(30 cm). Trees
are reported to have distinctive spines.
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- Sapwood Color
- The narrow sapwood is
usually yellow-white in color, and is clearly
distinct from the heartwood.
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- Heartwood Color
- The heartwood has an
almost black appearance. It is dark-purple brown in
color, with predominant black streaks.
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- Grain
- The grain is variable
but it is reported to be usually straight.
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- Texture
- The wood is described
as extremely fine and even-textured.
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- Luster
- Luster is reported to
be low to medium.
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- Odor
- There is no
characteristic odor or taste.
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- Ease of Drying
- The wood is reported
to require extremely slow drying rates, and could
take 2 to 3 years to season.
End-coating of logs or billets is reported to
be necessary to minimize degrade.
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- Drying Defects
- Common drying defects
are reported to be heart shake and end-splitting.
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- Kiln Schedules
- T2 - C2 (4/4); T2 -
C1 (8/4) US (End-coat
logs or billets.)
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- Movement in
Service
- African blackwood is
reported to be very stable after seasoning, and
shows only small movement in use.
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- Natural Durability
- The heartwood is
reported to be very resistant to decay.
The sapwood is susceptible to attack by
powder-post beetle.
The wood is reported to often contains
tunnels of Cerambycid
larvae.
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- Resistance to
Impregnation
- The material is
reported to be extremely resistant to preservative
treatment.
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- Blunting Effect
- The wood has severe
blunting effect on cutting tools.
- Tungsten/carbide
tipped saws are reported to be essential for
conversion.
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- Cutting Resistance
- Dry timber is
reported to be rather difficult to work and tends to
blunt cutting edges rapidly.
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- Planing
- The material is
reported to have good working qualities but it is
rather difficult to plane with either hand or
machine tools.
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- Turning
- The wood is
considered to be one of the best timbers for turnery
work, and turns to produce a smooth lustrous finish.
Metal-working tools are recommended for the
manufacture of woodwind instruments.
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- Boring
- Seasoned timber is
reported to be rather difficult to work in most
woodworking operations.
It responds poorly to ordinary machine tools,
and has severe and rapid blunting effect on cutting
edges.
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- Gluing
- The wood is reported
to have fairly good gluing properties.
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- Nailing
- Nailing is reported
to be difficult.
Pre-boring is necessary.
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- Screwing
- Pre-boring is
recommended. African blackwood is reported to
respond to tapping for screw threads almost as well
as metals.
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- Polishing
- The wood is reported
to finish to produce a brilliantly polished,
lustrous surface.
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- Staining
- The wood is reported
to have good staining properties.
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- Steam Bending
- The material is
reported to be too heavy and too dense to be used in
steam bending applications.
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- Comments
- African blackwood is
reported to be superior to Ebony for the manufacture
of woodwind instruments because of its oily nature
and high tolerance to fluctuations in climatic
conditions. It
is reported to respond almost as well as metals to
tapping for screw threads.
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