By Jo-Ann Kaiser
By Jo-Ann Kaiser
COMMON NAMES HEIGHT/WEIGHT PROPERTIES Two species known by the commercial name iroko grow in East and West Africa. Chlorophora excelsa is found almost everywhere across the width of tropical Africa, while Chlorophora regia, shorter in height and less hardy in prolonged dry conditions, is found in West Africa, from Gambia to Ghana.
Two species known by the commercial name iroko grow in East and West Africa. Chlorophora excelsa is found almost everywhere across the width of tropical Africa, while Chlorophora regia, shorter in height and less hardy in prolonged dry conditions, is found in West Africa, from Gambia to Ghana.
Iroko has many of the same uses of teak and is sometimes used as a teak substitute. While the tree is not related to the "true" teak, Tectona grandis, it has sometimes been called African teak or Nigerian teak.
The authors of the book The Illustrated Encyclopedia of Trees discuss iroko as a teak substitute. "The high price of teak with no likely prospect of substantial increase in volume of wood on the international market has, over the years, led to a degree of substitution by other timbers with more or less similar properties. For a long time, importers have tended to consider a 'new' timber in terms of a potential substitute for one already established. But increasing demand for wood and the availability of data from comprehensive trials by experienced timber-testing laboratories have helped to make more tropical timbers saleable under their own names." They add that for many years iroko was sold in the international market as West African teak but has now become recognized for its own properties.
A King Among Trees
Uses for the wood include ship and boat building, interior and exterior joinery, furniture making, cabinetry and carving. It is used to make decorative veneers and for making plywood. It is also used as a structural timber and its properties make it popular for use as railroad ties, piling and other marine work. Iroko is also used as domestic and parquet flooring.
The color of the wood from the tree varies from golden orange to light brown, to a rich golden brown. The tree has a pale yellow sapwood and a darker heartwood that, like teak, darkens with age in shady conditions but bleaches in the sun. Experts say that the fact that iroko bleaches in the open air and sun makes it a good substitute for teak in uses like boatbuilding and outdoor furniture. The wood's grain is usually interlocked and sometimes irregular with a coarse texture. The wood can contain hard deposits of calcium carbonate, sometimes called stone. If the calcium carbonate deposits are present, they are usually detectable because they are surrounded by darker material. The stones are sometimes large and hard and will damage saws and other cutting tools. Experts recommend the use of tipped or hardened saw teeth when cutting iroko.
A Good Teak Substitute
Other teak substitutes include cordia (Cordia alliodora) and afrormosia (Pericopsis elata). While teak grows well on plantations, iroko has not had that success, according to the authors of The Illustrated Encyclopedia of Trees.
The sapwood is vulnerable to attack by insects, especially the powder post beetle, but the heartwood is very durable. The heartwood resists preservatives; its sapwood can be treated. Outside of the problems associated when "stones" are present, the wood works well with most tools. The interlocked grain can pose problems in cutting and a reduced angle of 15 degrees is suggested. The wood nails and screws well. It will finish well, but experts recommend filling for the best results. The wood dries fairly quickly and well with few problems, but stick marks sometimes result. The wood has small movement in service.
One quirky thing about the tree is what happens after cutting. When freshly cut, the stump oozes a clear resin that covers the cut area and hardens, forming a glass-like surface that retards decay.
Have something to say? Share your thoughts with us in the comments below.