As can be seen in Figure 3, the initial brightness of each pulp differed significantly. Immediately noticeable is the especially low brightness of pulps obtained from hemp stalks subjected to the retting process, i.e. hemp wood (Hw-r) and hemp bast fibres (Hbf3), of around 29%. The initial ISO brightness of the remaining pulps ranged from circa 38 to 50%, being the highest in the case of birch pulp. The pulp samples were initially subjected to bleaching with chlorine dioxide (sequence D0EPD1).