Potencialidades dos extrativos do cerne da madeira de teca como preservativo natural e sua influência na cor de madeiras claras

Abstract

This study aimed to evaluate the preservative potential of the heartwood extractives from teak (Tectona grandis) and the capacity of the same in the color change of light woods. For both, the waste generated in mechanical processing of the teak heartwood with 20 years old were collected and used for performing extractions. To evaluate the influence of teak heartwood extractives in the color and natural resistance of timber, were used the sapwood of teak wood with 10 years and the wood of Pinus sp., due to being a light colored wood and with low natural resistance to wood-destroying organisms. Extractions were performed in hot water and absolute ethanol. To determine the concentration of treatment solutions, a toxicity test to fungus Postia placenta was performed. After set the concentration, the extracted solutions were prepared for impregnation. Furthermore, it was used a third solution, composed by mixing of extracted solutions in hot water and absolute ethanol. The treatment by the method of cell-full (Bethell) was performed for each treatment solution. To test the efficiency of the solutions prepared with teak heartwood extractives, colorimetric analyses and biological assays with fungi and termites were carried out. The combination of the tested extractives promoted a darkening and reduced the disparity of color, making the treated wood closer to the heartwood color than the untreated samples of the respective species. The extractive solution obtained in absolute ethanol and the combination of the extractives obtained in hot water and absolute ethanol provided the best results in the resistance of treated wood against fungi and ermites,significantly changing the biological resistance class of the respective treated species.