What is African blackwood?
African blackwood (botanical name: Dalbergia melanoxylon) is a small, heavily branched deciduous tree in the Family Leguminosae (=Fabaceae) that is widespread in sub-Saharan Africa. It normally reaches a height of 4-8 meters, very occasionally 19-20 m, and often has multiple trunks. Old trees may have a trunk diameter at breast height (DBH) approaching 1 meter, although few trees at present have a DBH over 50 cm. The tree and its timber have many different local and trade names. The most important local names are mpingo (a Swahili name used in Tanzania, Kenya and elsewhere in East Africa) and pau preto (Portuguese name for “blackwood”, used in Mozambique). Within the timber trade, the wood is often referred to as ebony or grenadilla, although both these names are also widely applied to other timbers.
African Blackwood is renowned for its beautiful dark coloured heartwood which in the best timber is inky black, but ranges from dark brown to even an indigo-purple tint. The cause of the variation has been the subject of much speculation, although it seems most likely to be linked to the rate of growth of the tree, with the paler wood, in which growth rings are generally visible, believed to be the result of faster growth. The rate of growth is itself almost certainly very largely a product of moisture availability and soil fertility - indeed the paler wood is sometimes referred to colloquially as "water mpingo". However, to date no studies have been carried out to determine whether there may be any genetic component in this variation or if it is entirely environmental.
It is considered to be the finest of all turnery timbers, cutting most exactly and finishing to a brilliantly polished lustrous surface. The heartwood of African blackwood may be extremely dark and dense, capable of reaching a density as high as 1350 Kg/m3. So hard, in fact, that it blunts axes, and as a result the tree is seldom cut for firewood and is sometimes left standing in fields. It is difficult to saw or plane and cannot be screwed or nailed without first drilling.
The heartwood is surrounded by a ring of creamcoloured sapwood, around 2 cm thick, with a density of around 750Kg/m3. This is significantly less resistant to insect and fungal damage than the heartwood, although large trees often suffer from heart-rot or fire damage. The heartwood is also attacked by at least one species of boring insect, the larva of a cerambycid beetle.
It dries very slowly and tends to split in drying, especially in log form. The application of moisture-retardant wax or paint to the end of the timber/logs is advised to minimize splitting.
Uses of the timber
The single most important export market for African blackwood timber is that to supply manufacturers of musical instruments, principally woodwinds and particularly clarinets but also oboes, bagpipes, wooden flutes and, in lesser amounts, other instruments or their parts.
Because of the demands placed on them, very few woods are considered suitable for the manufacture of woodwind instruments. The wood must be flawless, even-grained and capable of being worked to very fine tolerances. It must also resist the stresses of playing: when
blown into, the air inside the instrument changes in humidity and temperature, creating stresses between the inside and the outside of the instrument which may cause the wood to distort or split at points of weakness, such as between the keyholes. The dense, close-grained nature of African blackwood and its natural oiliness ensure that it meets these criteria better than any other known timber.
In addition to its use for musical instruments, it is sought after for ceremonial carvings.
It is also considered the best timber for ornamentals and turnery of cues, walking sticks, bobbins, cross of sport weapons and handles of cutlery.