The dyes also react with hydroxide ions present in the aqueous dyebath under alkaline pH conditions. This produces nonreactive hydrolysed dye which remains in the dyebath as well as in the fibre. In order to obtain the required levels of washing fastness, it is necessary to remove all unreacted and hydrolysed (unfixed) dye from the cotton fibre, it is achieved by 'washing-off'; a series of thorough ringing and 'soaping' steps. Around 50% of the dyeing cost is related to the washing-off and effluent treatment (Mosin et all., 2013). The dye remained on the fibre after washing-off is considered as dye fixed on the fibre. The dye fixation efficiency is typically in the range of 50-80% (Smith 2003); i.e.20-50% necessary to achieve the desired depth of colour is discharged to the environment.