Effects of Various Bleaching Chemicals on Some Surface Properties of Ebony Species (African, Black, and Macassar)

Abstract

The concept of color is not always suitable for some trees according to customers’ preferences. The color of the wooden material changes with processes such as heat treatment, impregnation, bleaching, etc. When the color of the wooden material changes, the surface also undergoes changes in its inherent properties. African ebony (Diospyros crassiflora Hiern.), black ebony (Diospyros ebenum), and Macassar ebony (Diospyros celebica Bakh.) wood species were treated using a single-component bleaching chemical [oxalic acid (C₂H₂O₄)] and double component bleaching chemical [hydrogen peroxide (H₂O₂) + sodium hydroxide (NaOH)] using a brushing technique. Subsequently, the characteristics of the changes that occurred were determined, including color parameters and whiteness index (WI*) values. The wood species exhibited different behaviors (increases and decreases specific to each test) in response to both bleaching agents. There was an observed increase in the a*, b* and C* values, while the h^o values decreased for all wood species. Furthermore, WI* values in directions perpendicular and parallel to the fibers were reduced in all wood species by oxalic acid treatment.