The Dramatic Beauty and Strength of Tigerwood
Tigerwood is an exotic wood species that is best known for its beautiful grain. With its deep reddish/orange background with dark vein stripes, it is a dramatic and durable hardwood.
Tigerwood is known by a variety of names – Brazilian koa, Congowood, African walnut, coubaril, bototo, zorrowood or muiracatiara, to name a few. Tigerwood may also refer to several different species of trees: Coula edulis, a tree species from tropical western Africa from Sierra Leone to Angola, Lovoa trichilioides, also African in origin, or Goncalo alves in South America (primarily Brazil). They all are evergreen varieties that prefer tropical or subtropical growing conditions, and all feature the same dramatic grain patterning, although the color may vary from region to region.
With trees growing up to a height of 80 feet or more, it can be found in the top canopy of forests as well as the lower story and has no special soil requirements. In fact, its growing popularity has led to export restrictions in Africa from some regions to limit over-cutting and excessive logging.
Tigerwood is considered very dense and heavy with a Janka hardness up to 2160 depending on the growing region (67% harder than Red Oak at 1210) and has a specific gravity (SG) of 0.45. It is naturally resistant to rot and decay and will not attract mold and fungus growth, which makes it extremely popular not only for exterior use but also for furniture work, veneers, flooring and other wood projects where the dramatic look gives a certain flair to the finished product.
Tigerwood is reported to air-dry well with some minor warping or checking (which can occur in extreme conditions) and it generally resists shrinkage and movement after drying. Tigerwood is dimensionally stable and resists twisting and warping, in the end, product. and will stand up well to wear.
Tigerwood has a wide range of coloring and striping. The striping can vary from fine lines to bold strokes and the color can have a large degree of color change from a light orange and tan to a deep reddish brown. It also has a highly lustrous surface that is considered almost oily in appearance.
Tigerwood is commonly used to produce flooring products and is considered very durable, and it resists denting and wear very well. What is interesting about tigerwood is that it is often graded differently than other species when used for flooring applications because of the dramatic coloring, which is what makes tigerwood so desirable. As an example, lesser grades such as #1 Common refer to small milling defects or the lack of streaks in the end product. Clear grade tigerwood flooring is color-sorted for a rich pink color with pronounced brown and black streaks.
Working with Tigerwood
Tigerwood is considered only moderately difficult to work with, especially with hand tools. Cutting edges may wear down more quickly than with other wood species, so carbide tips or bits are recommended for power tools. Pre-drilling is also recommended when screwing and nailing tigerwood. These steps are best to accommodate the wood’s properties, but of course also to serve to protect your investment in this exotic wood choice.
Sanding can also present more of a challenge with this hard exotic wood, and for large applications like floors, professional preparation is recommended.
Tigerwood can be sealed for longer durability but weathers well naturally as well; no preservatives are needed. Depending on the amount of sunlight the wood will receive, the color will often gradually darken over time, accentuating its distinctive grain pattern and giving it a slightly more subtle striping and increased luster.
Moisture Content in Tigerwood
As with any other wood species, moisture content (MC) is crucial to protecting the longevity of any tigerwood end product.
Tigerwood can be processed locally to reduce import/export expenses, especially in hardwood flooring applications. As an example, most (if not all) tigerwood hardwood flooring is milled in South America because it is more cost-effective to ship finished materials than the raw lumber itself.
It is typically dried to lower MCs for flooring applications, but as with any wood or wood product, it is vital to allow the wood to come to a gradual, natural balance with the relative humidity (RH) and temperature of the environment it will be installed and used in. This balance is referred to as the equilibrium moisture content, or EMC, and is of critical importance to preventing moisture-related problems in any wood product, but particularly in exotic woods that grow in dramatically different natural environments.
Using a wood moisture meter is the best way to accurately measure and assess the wood’s MC and to monitor the process of equilibration to its surrounding environment. Meters like the Orion® 930 Dual Depth pinless moisture meter have programmable SG settings for exotic woods as well as standard domestic woods, and can quickly and accurately measure the MC in both unfinished raw lumber and on finished products.
With accurate wood moisture measurement at every stage of the project, tigerwood end products will give years of dramatic strength and beauty wherever the end product will be used.
Larry Loffer is a senior technician at Wagner Meters, where he has over 30 years of experience in wood moisture measurement. With a degree in Computer Systems, Larry is involved in both hardware and software development of wood moisture measurement solutions.