Abstract: The present application relates to a process of colour neutralizing treatment liquids, wherein the treatment liquid comprises a chromophore selected from the group consisting of monoazo, triarylmethane, xanthene, anthraquinone, hydrophobic dyes, and mixtures thereof, wherein the hydrophobic dyes are selected from the group consisting of benzodifuranes; methine; triphenylmethanes; naphthalimides; pyrazole; naphthoquinone; mono-azo, di-azo dyes and mixtures thereof, said process comprising the steps of: i. providing a mixing vessel with the treatment composition comprising the chromophore; ii. providing to the mixing vessel more than 0.045% of a reducing agent selected from the group consisting of sulfite, thiodiurea, formaldehyde bisulfite formaldehyde sulfoxilate and mixtures thereof; and iii. mixing until discolouration by color neutralization of the chromophore is achieved.