A method for applying a water-absorbing polymer coating onto an optical fibre having a core, a cladding and at least a primary coating includes coating the optical fibre with an organic solvent-free radiation curable coating composition and initiating polymerization. The polymerization may be initiated with UV light. The coated optical fibre may be combined in a tubular or flat sheath, e.g., as a multi-fibre cable or ribbon. The coated optical fibre may be a coloured coated optical fibre.