Study on the dyeing properties of Chinese fir with Cinnamomum camphor pigment by premordant dyeing

Wood staining can improve the quality of Chinese fir. In this study, Cinnamomum camphora natural plant pigment was used as a substitute for synthetic dyes to stain Chinese fir, and the staining performance was enhanced through pre-mordanting with alum. The dyeing effects of direct dyeing and mordant dyeing were compared, and the factors and levels influencing color difference, wash fastness, and light fastness were investigated through an orthogonal experimental design. The results showed that mordanting time had the greatest influence on color difference and lightfastness, while mordanting temperature had the greatest influence on washfastness. After pre-mordanting, the washfastness of Chinese fir improved to a level of 2–3, while the improvement in lightfastness was not significant. Pre-mordanting increased the dye uptake rate by 6.67%. Scanning electron microscopy revealed that NaOH pretreatment opened the wood pores and increased the flow channels for dye liquor. Infrared analysis indicated that O-H in wood fibers formed complexes with Al3+ in the mordant, resulting in a decrease in the characteristic peak intensity of O-H. X-ray diffraction analysis showed that the attractive effect of Al3+ vacant orbitals on O-H partially influenced the ordered arrangement structure in the crystalline region.</p

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

To improve the permeability of wood, three chemical reagents were used to pretreat Chinese fir, white oak, and poplar. Through a factorial experiment with the mass change rate of the wood as the indicator, NaOH was preliminarily selected as the pretreatment agent. Further orthogonal experiments were conducted to explore the effects of NaOH concentration, temperature, and treatment time on the mass change rate, dye uptake rate, transverse dye penetration rate, and color difference of the wood. A fuzzy, comprehensive analysis was used to optimize the pretreatment process. The results showed that after NaOH pretreatment, the highest mass change rates of Chinese fir, white oak, and poplar were 11.30, 10.66, and 8.53%, respectively. Compared with untreated wood, the dye uptake rate of three wood species increased by 1.05, 1.43, and 1.13 times, respectively; the radial dye penetration rate increased by 5.05, 4.14, and 3.38 times, respectively; and the tangential dye penetration rate increased by 3.91, 3.45, and 3.84 times, respectively. These findings indicate an enhancement in permeability for all three wood species following NaOH pretreatment. The brightness of the three wood species decreased after NaOH pretreatment, while the yellow and red colors increased in Chinese fir and poplar and decreased in white oak. Scanning electron microscopy showed that pits in the wood opened after pretreatment, while extractives decreased. Infrared spectroscopy analysis indicated varying degrees of extraction effects from NaOH pretreatment across the three wood species, along with increased active hydroxyl groups within the wood structure. X-ray diffraction analysis revealed that NaOH dissolved noncrystalline substances in wood, leading to improved crystallinity. These experimental findings provide essential data for future endeavors in wood pretreatment and subsequent staining processes