Study on the dyeing and lightfastness of oak and maple veneers using synthetic and natural dyes

Veneer dyeing is typically carried out to achieve a desired colour in the veneer while allowing the grain to show through or to reduce colour variations and achieve a more uniform appearance. In this study, the influence of dyeing temperature, dyeing time and the addition of mordants on the colour and lightfastness of oak and maple veneers was investigated. Wood veneers were dyed using two synthetic dyes (reactive and acid) and two natural dyes (madder and logwood). The study analysed colour change, colour strength and grain contrast after dyeing, as well as colour stability and depth of colour change after artificial exposure. The results showed that temperature, time, and mordant addition had a greater impact on the colour change and colour strength of veneers dyed with natural dyes compared to those dyed with synthetic dyes. On most veneers, higher grain contrast was achieved at lower dyeing temperature and shorter dyeing time. Additionally, mordants reduced the grain contrast of reactive and natural dyes. Furthermore, veneers dyed with natural dyes exhibited less colour change during artificial exposure compared to those dyed with synthetic dyes. Among the tested dyes, the best lightfastness for oak and maple veneers was achieved with madder natural dye.