Most low durability timber are treated with waterborne preservatives consisting of metallic salts, however, these substances make the process expensive and are harmful to man and the environment, requiring cares with handling, dosing and leaks. Due to these facts, several researches have shown the use of natural substances, extracted from the wood of various naturally durable species, as potential natural preservatives. This study aimed to evaluate the preservative potential of the heartwood extractives of teak (Tectona grandis) against Nasutitermes corniger termite. Therefore, the waste generated in the mechanical processing of teak heartwood with 20 years old was collected and used to perform the extractions. To verify the effectiveness of extractives obtained, were acquired in the local commerce boards of Pinus sp. because is a wood with low natural durability. Extractions were performed in hot water and absolute ethanol. The extracted solutions were concentrated to 4% (w:v) and prepared for impregnation. Furthermore, a third solution, composed by the combination of the solutions extracted in hot water and absolute ethanol was used. Each treatment solution was impregnated by the full-cell method (Bethell). To prove the effectiveness of the solutions prepared with teak extractives, a forced feeding test to Nasutitermes corniger termite was performed. The extractives solution obtained in absolute ethanol and the combination of extractives obtained in hot water and absolute ethanol provided better results in the resistance of treated wood against the termite tested, changing significantly the mass loss and the time to death of the tested termites.

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