African Blackwood Burl
- Burl wood is a type of wood used by artists to create sculptures and other items, such as clocks and even some forms of furniture. Burl wood is highly prized by artists because of its unique shapes and ring patterns. Burl wood is a type of fast growing, abnormal growth found on some trees. Burl wood grows because the tree has experienced some sort of environmental stress or damage. This is often caused by either a fungal attack or an attack by insects. The number of trees that produce burl wood is quite low. In addition, certain areas tend to create more burl wood than others, because all or many of the trees in a particular location are likely to be attacked by the same fungus or insects. Certain species also tend to be more susceptible to attacks and, therefore, more likely to develop burl wood. For this reason, certain types of burl wood are more rare and prized than others.
- Environmental Profile
- The environmental status of this species within its natural habitat has not been officially determined.
- Distribution
- African blackwood burl 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.
- Product Sources
- Some material from this species is reported to be available from sustainably managed or other environmentally responsible sources.
- The International Tropical Timber Organization (ITTO) reports that timber from this species is produced in limited volumes and is exported in small sized cants.
- 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).
- Heartwood Color
- The heartwood has an almost black appearance. It is dark-purple brown in color, with predominant black streaks.
- Luster
- Luster is reported to be low to medium.
- Odor
- There is no characteristic odor or taste.
- Ease of Drying
- The wood is reported to require extremely slow drying rates, and could take 2 to 3 years to season.
- Resistance to Impregnation
- The material is reported to be extremely resistant to preservative treatment.
- Blunting Effect
- Tungsten/carbide tipped saws are reported to be essential for conversion.
- Cutting Resistance
- Dry timber is reported to be rather difficult to work and tends to blunt cutting edges rapidly.
- 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.
- 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.
- Polishing
- The wood is reported to finish to produce a brilliantly polished, lustrous surface.
Burl Wood
Often, a tree that has developed burl wood is still quite healthy. In fact, many trees with burl wood can go on to live for many more years. Other trees develop burl wood offshoots that are so large and heavy that they create additional stress on the tree and can cause the tree to die.
When used in woodcrafting, burl wood is removed from the tree, preferably after the tree has already died in order to avoid killing the tree. It is then cut open in order to review the pattern inside. Sometimes, a single burl wood offshoot can produce several different pieces for an artist to work with.
Some burl wood offshoots develop regular growth rings that simply grow at an accelerated rate. This type of burl wood is not as sought after by artists as other forms of burl wood, because the patterns on this wood are not as interesting to look at. The majority of woodworking artists prefer burl wood that grows in irregular patterns that swirl and contain what are referred to as eyes – small spots that develop on the wood. While pieces with unusual patterns are the most desired form of burl wood, they are also the most difficult to work with. This is because the irregular patterns of burl wood make it harder to saw, chisel, and cut without splitting the wood or accidentally cutting it in the wrong direction.