Colorability of Dyed Wood Veneer Using Natural Dye Extracted from Dalbergia cochinchinensis with Different Organic Solvents

The colorability of wood veneers was evaluated with a natural dye that had been extracted using four different organic liquids. The solvent with the optimal dye effect was selected by measuring their total color difference. In addition, the dyeing mechanism, color fastness of water, and thermal stability of the dyed samples with the optimal dye effect were also investigated. The results showed that the absolute ethanol extraction can obtain dyed samples with a maximum total color difference accompanied with a satisfactory color fastness of water. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses suggested that only physical absorption occurred between the natural dyestuff and wood tissues, and the distribution form of natural dyestuffs was akin to the membrane covering the wood vessel wall, wood fiber lumens, ray cells, etc. Moreover, thermogravimetric (TG) results revealed that the residue of the dyed samples was more than that of the untreated samples, which indicated that the thermal stability of wood veneers can be improved after the dyeing process.