Physical Properties of Neem Wood

India accords high honor to the neem tree. Its leafy crown makes it a popular shade tree. In traditional Indian medicine, extracts from its seeds served as treatment for such ailments as leprosy, and its bark treated such diseases as malaria. Ancient Hindu lore also attributed spiritual properties to the neem tree. They believed that anyone planting it would spend considerable time in a paradise called Suryalok after death. However, aside from metaphysical considerations, the neem tree possesses material value because of its excellent wood, which possesses many desirable physical properties.

The neem tree, also known as the Indian lilac or margosa tree, has the scientific name Azadirachta indica and belongs to the botanical family Meliaceae. Mahogany trees belong to a different genus (Swietenia) of the same family. The wood of these two closely related trees have similar characteristics, including similar heartwood that ranges in color from reddish to reddish brown. This attractive color gives neem wood furniture an aesthetically pleasing appearance.

Like mahogany, neem heartwood is strong and durable. Its grains are interlocked, and consequently the wood does not split apart very easily. Because of its strength, it serves as a material for constructing oars, cart axles and felloes for cart wheels. It also is a fairly heavy wood. Its specific gravity ranges from 0.72 to 0.83 when air-dried, according to the United States Agency for International Development.

Neem heartwood has a coarse, rough grain with interlocking fibers. While this property gives neem wood a sturdy texture, it is difficult to polish coarse, interlocking grains. As a result, furniture makers who want to make a highly polished product avoid using neem wood.

In spite of its coarse grain, neem heartwood is fairly easy to work. The application of either machine or hand tools yields satisfactory results. It can even be crafted into toys.

According to tests conducted by the Federal University of Technology in Yola, Adamawa State, Nigeria, the wood of neem trees in the savannas of western Africa have an average volumetric shrinkage of 19.12% while drying out. The study concludes that this shrinkage percentage is relatively high, but offers the observation that wood from some of the other timber trees in the area show greater shrinkage.

Neem wood is mildly aromatic. Neem wood products have a slight fragrance, especially when used for paneling or ornamental ceilings, according to the Royal Botanic Gardens.

The heartwood of the neem tree resists such pests as wood borers and termites. The wood contains a natural pesticide as part of its composition.