Peroxide bleaching for bast fibres?
Old patents of the 1930s, particularly from I.G. Farben often describe the use of hypochlorite/chlorine in the bleaching of bast.

However, from newer literature, such as this application manual for hydrogen peroxide bleaching from Evonik Industries, I would conclude that bleaching of bast can be performed without chlorine, supposed that the peroxide bleaching is performed 


in alkaline medium
at elevated temperatures $(85-90\,°\mathrm{C})$