Discriminating the brightness stability of cellulosic pulp in relation to the final bleaching stage

► Difference in hydrothermal decay of H2O2 and ClO2 bleached pulps was studied. ► Worst brightness stability of ClO2 bleached pulp was assigned to retained oxidised structures. ► Leachable ageing products were assessed by mass spectrometry. ► A part of formed chromophores was the result of iron complexes with ageing products. ► The products of carbohydrate origin arisen during pulp ageing are strong contributors to the pulp yellowing.