Surface chemical and color characterization of juvenile tectona grandis wood subjected to steam-drying treatments

The color of Tectona grandis wood is an attribute that favors its commercialization, however, wood color from fast-growth plantation trees is clear and lacks uniformity. The aim of this work is to characterize steamed teak wood by means of the Fourier transform infrared spectroscopy (FTIR) and L∗a∗b∗ color systems. Two moisture conditions (green and 50%) and two grain patterns (flat and quarter) of boards were analyzed through the application of different steaming times (0, 3, 6, 9, 12, 15 and 18h). The FTIR results showed that the bands at 1158, 1231, 1373 and 1419cm-1 did not show any change with steaming, whereas the bands at 1053, 1108, 1453, 1506, 1536, 1558, 1595, 1652, 1683, 1700 and 1733cm-1 presented a decrease in the intensity with the steaming time. The band at 1318cm-1 was the only one that increased. Lightness (L∗) was the most affected parameter, followed by yellowness (b∗), while redness (a∗) showed the smallest change. Surface color change (ΔE∗) presented the lowest value between 3h and 6h of steam-drying in the boards with flat grain, whereas for boards with quarter grain, the smallest ΔE∗ value was obtained after 18h of steaming.