Color Improvement of Pretreated Gmelina Wood by Impregnation of Natural Dyes
The purpose of this research was to improve the appearance of pretreated gmelina wood (Gmelina arborea) by coloring with a natural dye. The dyes used in this research were obtained from sappan (Caesalpinia sappan) and tegeran (Cudrania javanensis) wood waste with a size of 20-40 mesh. The anatomical characteristic that determined the permeability of the gmelina wood was investigated referring to International Anatomist Wood Association (IAWA), while the characteristic of the dye was analyzed using X-ray diffraction (XRD). The wood was colored by immersing in dye mixture (ratio dye and water of 1:5 wt/wt) at room temperature during 72 h. The results showed that the lumen diameter of vessel, fiber, and pit of gmelina observed were 159 μm, 23 μm, and 6 μm, respectively. The XRD analysis showed that the structure of sappan was more amorphous than tegeran, which led to penetrate deeper into the wood. The pretreated wood provided more dyes penetration compared to the untreated wood due to the removal extractives from the wood. The pretreatment on gmelina wood would facilitate the natural dye to be impregnated into the wood cell resulting in more attractive color of the wood.