New Drying Process Gives Black Locust Wood Exotic Appearance
Black locust wood is a fast growing species with superior mechanical properties and is often used in making furniture. However, discoloration during drying often limits its application, necessitating a better understanding of heat treatment variables in order to enhance the black locust's wood color. Heat treatment creates the potential for black locust wood to resemble exotic hardwoods, thus increasing the use of this fast growing wood species, and potentially decreasing demand for exotic foreign species.
Forest Service scientists report that heat treatment variables can affect color changes in wood and color change is largely due to chemical structures within the wood. The first phase of this project investigated the effects of oxygen and moisture content on the chemical and color changes of black locust wood during heat treatment. Results indicate that oxygen (as an oxidation medium) plays an important role in the darkening of wood during heat treatment.
Initial moisture content of 30 to 50 percent humidity appears sufficient to produce the darkening of the wood but higher moisture contents are required to produce sufficient darkening of the wood when exposed to nitrogen. The second phase included investigating the chemical and color changes at the polymer level within extractive-free black locust wood during heat treatment. Results suggest a range of alternative, suitable drying processes that can be used to produce black locust wood with a surface color closely resembling other desirable exotic hardwoods.
Forest Service Partners