Colorimetric properties of wool dyed with natural dyes after treatment with ammonia

Abstract

An evaluation has been carried out of the effect of ammonia on the colouristic properties of wool dyed with a range of natural dyes containing anthraquinone, naphthaquinone, flavone and tannin structures. It was found in all cases that after‐treatment with ammonia caused a decrease in the lightness ( L *) values. The reasons for this are discussed, as is the fact that the colour change is not reversible on subsequent treatment with acid.