Wood of the Month:
Ekki: Heavy Tree Puts 'Hard' in Hardwood

By Jo-Ann Kaiser

Lophira alata of the Family Ochnaceae

Red ironwood, kaku, eba, azobe, bongossi, adoura, hendui, esore, aba, endwi and bakundu.

Trees grow to 180 feet with diameters of 5 to 6 feet. Average weight is 65 pounds per cubic foot.

Wood is hard to season, dries very slowly and has tendency to warp and split. Ekki is very durable and decay-, insect- and fungal-resistant. Wood is hard to work with hand tools but works somewhat easier with machine tools. Wood has high resistance to wear as well as natural acid and water resistance. Wood is extremely resistant to preservative treatment. Ekki is a popular choice for heavy construction and marine work. It is not recommended for steam bending. Preboring needed for gluing and nailing. Filling usually needed to finish properly. Grain is usually interlocked. Wood commonly has pore deposits or white flecks.

Wood is hard to cut and has severe blunting effect on tools. Wood has a low luster. No natural odor or taste. Wood has good weathering properties.

As woods go, ekki is a workhorse. It is noted more for its impressive strength and difficulty in working than its appearance. These characteristics have resulted in a long list of practical rather than decorative uses.

Ekki grows principally on the West Coast of Africa, from Sierra Leone to Nigeria and the Cameroons in the heavy rain forests and swamps.

The wood's most common names are ekki and azobe, but it is also called red ironwood, likely due to its extreme hardness and strength and the tendency for the dark-colored wood to have a red tinge.

Tough Enough for Building Stuff
Ekki is classified as "exceptionally heavy" with a weight that averages 65 pounds per cubic foot. It is considered by many to be one of the most durable of all the African woods.

In the book Know Your Woods, Albert Constantine sums up the wood's dual personality, writing that ekki is used "when great strength is required, as in flooring, where the wood is subject to a good deal of wear. It is extremely difficult to season, however, because of the tendency to warp and split."

Ekki's properties make it a perfect material for heavy construction or other uses where great strength and durability is needed. Typical applications for ekki include wharfs, bridges, sea fences and river pilings because of the wood's strength and resistance to decay. It is also used for other forms of heavy-duty construction such as decking, railway sleepers, railroad crossties, mine shaft guides, heavy-duty and parquet flooring, rollers, wagons and joinery. In addition to being durable, the wood is very acid-resistant, which makes it good for use in filter press plates and frames.

Other reasons that the wood is so well suited to heavy construction and marine uses is that the wood is resistant to insect and fungal attack.

One of its more interesting uses, according to The Encyclopedia of Wood, is as the running track for the rubber-wheeled trains of the Paris Metro.

Putting the 'Hard' in Hardwood
Ekki might have more widespread use, but the wood is difficult to work with hand tools and poses some problems with machine tools, too. Ekki is so hard a wood that it severely blunts the surfaces of cutting tools. To combat this problem, experts recommend using strong, sharp cutting edges and reducing the cutting

On the other hand, ekki does offer some desirable properties in addition to its strength. The wood takes finish well and has good gluing properties. The wood has medium movement in service.

Ekki's grain is usually interlocked and can be irregular. It has a coarse and uneven texture. Ekki has high bending strength and stiffness, high crushing strength and extremely high resistance to shock loads. The wood is not recommended for steam bending.

A Slow Drier
Drying ekki can pose problems. In addition to drying slowly, the U.S. Department of Agriculture Forest Service Handbook describes it as "very difficult to season without excessive degrade, particularly surface and end checking." The USDA recommends a kiln schedule of T2-C2 for 4/4 stock and T2-C1 for 8/4 stock. Experts also suggest piling the timber with care.

Beauty Is in the Eye of the Beholder
The wood varies from a dark red to a dark brown, chocolate-like color with very pronounced white streaks and deposits in the pores. These white deposits can sometimes give the wood a speckled appearance and produce white streaks against a dark background. Its sapwood is clearly demarcated from the heartwood and is pale pink in color. Ekki can be finished satisfactorily, but the grain usually needs to be filled to get the best finishing results.

Ekki's weight varies from 59 to 70 pounds per cubic foot making it exceptionally heavy and dense. To put the weight into perspective, other woods' average weight include: white oak, with an average weight of 47 pounds per cubic foot; hard maple, with an average weight of 45 pounds per cubic foot; and teak, with an average weight of 41 pounds per cubic foot. Lignum vitae, which is considered one of the hardest and heaviest of commercial timbers, has an average weight of 77 pounds per cubic foot.


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