Chromatic and medicinal properties of six natural textile dyes: A review of eucalyptus, weld, madder, annatto, indigo and woad

The environmental and health-related impacts of synthetic dyes have led to growing interest in natural dyes as sustainable and eco-friendly alternatives. However, natural dyes have been used to dye textiles with limited color shade and poor fastness properties, and little research has been conducted in this field. Additionally, natural dyes also have the potential to provide added functionalities to textiles, such as antibacterial and anti-UV properties. A systematic literature review of 38 studies was conducted to analyze the use of six natural dyes derived from eucalyptus (Eucalyptus globulus Labill.), weld (Reseda luteola L.), madder (Rubia tinctorum L.), annatto (Bixa Orellana L.), true indigo (Indigofera tinctoria L.) and woad (Isatis tinctoria L.). These dyes were selected after a preliminary analysis of studies on plant-based natural dyes with primary colors, considering their chromatic and potential medicinal properties. This study explores the influence of different dyeing parameters and auxiliary products in these properties. The research discussed how the chromatic and medicinal properties of natural dyes can be affected by various factors and provides a summary table with the chromatic palette possibilities according to the different materials and processes relationships. Exploring the combination of natural dyes with environmentally friendly auxiliary products can be a promising development area for creating a wide range of color shades. Further research is also needed to optimize the dyeing processes with natural dyes, towards more sustainable textile dyeing possibilities.