Vegetable colours are more beautiful!
Exactly when people started colouring their clothes is impossible to find out, but the tradition reaches back thousands of years. Until synthetic dyes were invented in the nineteenth century, textiles were dyed almost exclusively with dyes obtained from plants. Weld is one of the most important dyeing plants and is famous for its excellent washingfastness and lightfastness. In the Middle Ages it was one of the few dyes that could be used for high quality dyeing in what was called the 'grand teint' in France and 'Schönfärberei' in Germany.
Synthetic dyeing (provided it is environmentally friendly) has certain advantages: it is more efficient, cheaper, and it does not cost agricultural land. On an aesthetic level, however, the synthetic dyes can’t compete with the vegetable. Vegetable colours are more vibrant and richer. Unlike synthetic dyes, which always consist of only one colouring molecule, vegetable dyes are always the result of the synergy of several colouring substances present in the plant, sometimes even of different chemical groups and (almost) colourless substances. In other words: synthetic dyes have a flatter colour image, while the color of vegetable dyes consists of multiple components, which ensures a richer colour image.