Investigations have been made on the colour reversion of both ligneous and rag fibre papers bleached with different solutions: hypochlorite, chloramine-t, chlorine dioxide and stabilized hydrogen peroxide. The effect of anti-chlor upon the rate of yellowing, as well as the possible influence of encapsulation of the paper artifact with mylar have been considered. The contribution of the extent of oxidation and chlorination of the cellulose and lignin components of the papers on the rapidity of colour reversion is discussed.