Silk Fabric Dyeing with Red Onion Skin

— A Comparison between Red Onions and Brown Onions —

Abstract

  Silk fabric was dyed using the extract from red and brown onion skins, and the properties of the dyed fabrics were investigated. The main natural colorant present in the red onion skin was identified as malvidin-3-arabinoside of the anthocyanins. The red onion skin contained yellow colorants, as did the brown onion skin. The colors of the fabrics dyed with and without six types of mordants, including Mg^2＋, Ca^2＋, Al^3＋, Ti^4＋, Fe^3＋ and Cu^2＋, were measured and expressed according to the CIELAB color system and ΔE^* value. The fabrics were dyed pink without mordant and dyed green with Al^3＋ and Cu^2＋ mordants using the red onion. An investigation by FE-SEM, EDS, XRD and TG-DTA revealed that the dyeing did not affect the structure of the fabrics. Color fastness to light and to washing of the dyed fabrics was enhanced by treatment with Al^3＋, Ti^4＋, Fe^3＋ and Cu^2＋ mordants.