May 31, 2014 | 7:00 pm CDT

Ipe (pronounced eee-pay) is a group of 20 species belonging to the genus Tabebuia. This genus has within it four groups white cedar, roble, lapacho and everything else. Ipe refers only to species in the lapacho group. Main species are T. heptaphylla, T. chrysanthak, T. serratifolia, T. rufescens and T. guayacan. The last species is abundant in Central America, the others in South America.

Ipe grows throughout Central and South America. Although the tree, which can reach 150 feet tall with 60 feet clear of branches, and 3 feet in diameter, has many regional names, the lumber when imported into North America is called ipe. Because the 20 species that belong to the ipe are quite varied in properties, including color, ipe lumber can vary greatly in physical properties.

Overall, the wood is extremely dense, heavier than water in some cases. It is therefore exceptionally strong, stiff and difficult to machine. It is also naturally very durable when exposed outside. This wood is ideal for flooring, especially industrial flooring with high traffic and heavy loads, outside decks, boardwalks and playground equipment.

Processing suggestions and characteristics

Density. The density when green ranges from 0.85 to 0.97. When dried to 6 percent MC, the weight is approximately 68 pounds per cubic foot, with considerable variation. This is about 5-1/2 pounds per board foot.

Drying. Although the wood dries slowly, defect development is minimal. In the North American market, supplies would include both air-dried and kiln-dried. For exterior use, 12 percent MC would be ideal.

The wood shrinks, from green to 6 percent MC, about 6 percent tangentially (the width of flatsawn lumber) and 5 percent radially. Due to cross-grain, some lengthwise shrinkage may be noted.

Gluing and machining. The wood contains cross-grain, which makes machining difficult in any species. Add to that the high density of this wood, and the net result is extremely difficult machining. Knives dull rapidly. However, the machined surface is very smooth and polishes well.

Gluing is difficult due to its density and tight grain.

Stability. The wood is moderately stable with changes in moisture content. It will shrink or swell 1 percent in size with a 3.5 percent MC change tangentially, and 4 percent MC change radially.

Strength. This is an extremely strong wood. The ultimate strength (MOR) is 25,400 psi, the stiffness (MOE) is 3.14 million psi and the hardness is 3,680 pounds. Comparable values for red oak are 14,000 psi, 1.8 million psi and 1,300 pounds. In other words, ipe is nearly twice as strong and stiff as oak and three times as hard. It is no wonder that machining is so difficult.

Predrilling of nail and screw holes is essential. Because the wood is often used outside and would be at 12 percent MC, it will machine a little easier and fasten a little easier than if it were at 6 percent MC. In fact, at 6 percent MC, "life will be tough."

Color and grain. The color varies, depending on the species. Grayish-green, brown and grayish-brown would be typical. The sample here is more reddish brown. The grain is smooth, fine and tight. A wax finish may be the best choice in many cases for a finishing system.

The dust can cause allergic reactions in some people.

The wood can contain a chemical, lapachol, which is naturally yellow in color, but will turn deep red if exposed to alkaline.

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About the author
Gene Wengert

Gene Wengert, “The Wood Doctor” has been training people in efficient use of wood for 45 years. He is extension specialist emeritus at the University of Wisconsin-Madison.