Wood of the month: pau marfim, the cream colored "ivory" wood from South America (pau marfim, the cream colored "ivory" wood from South America)

WOOD OF THE MONTH

Located primarily in Brazil, Argentina and Paraguay, pau marfim has been a popular hardwood species in North America since its introduction to the market in the late 1960s.

It bears a strong resemblance to birch and hard maple and shares many of the same uses. A popular species for fancy turnery and also carving, its other uses include furniture, cabinet work, tool handles and flooring. In the past, pau marfim has received "sweeping" acclaim, being exported to countries worldwide for the manufacture of broom handles.

In addition to the many uses listed, pau marfim is also used in the countries of origin to make oars, textile rollers, drawing instruments, rulers and implements. Pau marfirm can also be sliced as a decorative veneer for architectural uses and for marquetry.

Growing range

Pau marfim has a very definite growing range where the slender trees flourish. In Brazil, that range is the state of Sao Paulo. In Paraguay, it is the north and central regions. In Argentina, pau marfim can be found in the Selva Missionera or northern part of the country, although top grades are becoming increasingly scarce.

The pau marfim tree is moderate in height, averaging 80 feet with diameters of 2.5 feet. Pau marfim, (Balfourondendron riedelianum) is a member of the Family Rutaceae.

It is a heavy, dense wood with an average seasoned weight of 50 pounds per cubic foot and an average specific gravity of 0.63 (based on the volume when green and weight when oven dry). As mentioned it looks quite a bit like birch and hard maple and can be substituted for many of those trees' common uses. In comparison, birch weighs an average of 39 to 41 pounds per cubic foot and hard maple weighs approximately 45 pounds per cubic foot.

Pau marfim is a compact, finely textured wood with a sapwood almost identical in color to the heartwood. The light colored wood is creamy yellow with occasional dark streaks. Its grain can be straight or irregular and the wood has a fine, even texture and medium luster. One wood expert explained that pau marfim's properties of strength and hardness are especially ideal for flooring and handle usage. Those with a natural luster are good for carving and turnery as well.

Pau marfim, like any wood used for flooring and tool handles, is extremely hard, heavy and dense and, therefore, suited to tough uses. While rated highly for strength, it is of no value for steam bending purposes.

Pau marfim can be dried without appreciable degrade or difficulty. The U.S. Department of Agriculture suggests a kiln schedule T6-C3 for 4/4 stock and schedule T5-C2 for 8/4.

This wood works well with both hand and machine tools, however, it can have somewhat of a blunting effect on cutting tools. It nails, screws and glues well. The wood can be finished very successfully. The only problems that can occur happen when the grain is irregular or interlocked; then, planing and moulding can result in tear outs and extra care is needed.

Pau marfim is a non siliceous and non resinous wood without distinctive taste or odor. According to the USDA, other mechanical properties for the green wood include: a bending strength psi of 15,170; modulus of elasticity (1,000 psi) at 1,665 and maximum crushing strength at 6,320 psi. Material with 15 percent moisture content would have the following ratings: bending strength: 19,870 psi, modulus of elasticity: no rating and maximum crushing strength: 8,535 psi.

Pau marfim is not rated highly for durability as the wood is susceptible to insects. The heartwood is resistant to preservative treatment, but the sapwood is permeable.

Aliases, similarities and specifics

Pau marfim is known by a variety of names, among them moroti, guatambu moroti, farinha seca, quatamba, pau liso, kyrandy, quillo bordon and yomo de heuro. In the United States, the name ivory wood - which is a literal translation of "pau," meaning wood, and "marfim," ivory - is still a commercial name used for the wood.

In his book, "Know Your Woods," Albert Constantine Jr. said the name was due to the close, compact grain, with a smooth surface resembling ivory. In Argentina, the wood is most often called guatambu blanco, and in Brazil it would probably be most often referred to as pau liso. Guatambu blanco, loosely translated, means white wood. The Portuguese term for wood is palo teamed with blanco or white wood again. Some places simply shorten the name to marfim.

Yet with all its aliases, pau marfim is also a name used for a completely different species of pale colored woods. In South America, trees of the species Aspidosperma also are called pau marfim or variations of the name marfim. They resemble Balfourodendron riedelianum because of their pale, creamy coloring and fine texture.