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TRIPLOCHITON SCLEROXYLON
Other names
The Nigerian name obeche and the Ghana name wawa have been adopted as
alternative British Standard names for the timber of this species; obeche
is the usual trade name in Britain. The names ayous and samba refer to
timber originating in Cameroon and the Ivory Coast, respectively.
Distribution
West Africa, Nigeria, Ghana and the Ivory Coast.
The timber
The wood is creamy-white to pale-straw in colour with no clear distinction
between sapwood and heartwood, though the wide sapwood is more susceptible
to discoloration and insect attack. It is the lightest low-cost utility
hardwood in general use, the density being about 0,38 seasoned. The grain
is slightly interlocked; the texture open. When cut on the quarter and
stained it has some resemblance to African mahogany. Large logs commonly
contain brittleheart.
Strength and bending properties
It is fairly elastic and resilient, considering its weight, but should
not be used for purposes where strength is critical. Wood from the centre
of large logs is inclined to be brittle (brittleheart). On the basis of
laboratory tests it is classed as moderately good for steam bending.
Durability and preservative treatment
Obeche is not resistant to decay or staining fungi. Freshly felled logs
are extremely prone to attack by pinhole borer beetles, and seasoned timber
is often infested by powder-post beetles. In regions where termites are
present obeche is very liable to be damaged. The heartwood resists preservative
treatment.
Working and finishing qualities
Although it cannot be described as hard, the wood is firm under the tool,
and even in texture. It works very easily with hand and machine tools,
and does not blunt cutting edges of tools very quickly. In end-grain working,
the timber may show a tendency to crumble, unless the tools are kept sharp,
and edges are not allowed to become thick. It can be turned but is rather
soft for this type of use as centres are apt to sink in. For jointed work,
gluing is preferable to nailing or screwing, except for very light work.
It stains and polishes well (the grain needs to be filled). The wood takes
paint well with normal primers.
Uses
Obeche is readily obtainable in large sizes, clear of defects, and at
a fairly low price and is ideal for mass-production work. It is used in
the manufacture of lower-priced domestic cabinet work and kitchen furniture,
and for interior joinery and similar purposes where American whitewood
or joinery-grade softwood were formerly specified; also for boxes and
packing cases where a good appearance is required, since less wastage
occurs in conversion. Obeche should never be used without preservative
treatment in exposed or damp situations.
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