Effect of Vacuum Pretreatment on the Dyeing Properties of Wood Veneers Dyed with Camphor Fruit Pigment

Abstract

Vacuum pretreatment, valued for low energy use and sustainability, has attracted attention in wood dyeing. Using an orthogonal experimental approach, the vacuum pretreatment parameters were optimized for Chinese fir, poplar, and white oak veneers. The ideal circumstances were as follows: Chinese fir −0.08 MPa/90 °C/30 min; poplar −0.09 MPa/90 °C/30 min; and white oak −0.09 MPa/90 °C/90 min, based on color difference (∆E*), mass change, and water absorption weight rise. After the veneers were dyed with a camphor fruit pigment solution, the effect of the pretreatment on the microstructural alterations and macroscopic dyeing performance was assessed. The dye penetration depth and absorption rose by 60% to 95% following pretreatment. Reflectance spectra and ∆E* values showed that the treated samples had more consistent and vibrant coloring. Additionally, there was a minor improvement in the lightfastness of all three wood types. According to microstructural research, the pretreatment increased the distribution of binding sites for interactions between dye molecules and the wood matrix by partially opening the vessel components and cell wall structures. In summary, vacuum pretreatment significantly improved the dye’s homogeneity and fixing in wood veneers, offering a practical and environmentally friendly method of effective wood processing.