Disclosed is a method for dyeing solution dyed bulk continuous filament (BCF) fibers. The BCF fibers are twisted together to form a 2 or more ply strand prior to dyeing. After twisting the fibers together, the fiber is preferably spaced dyed to provide a multi-colored pattern along the length of the strand. Following the space dyeing step, the strand is heat set.

A method is provided for treating the surface of a shaped melded part produced with a plastic having ester, ketone and/or ether bonds. The plastic is selected from the group including a polymer, copolymer, polymer blend and combinations of the same. The method includes a pretreatment step for cationically modifying the surface of the melded shaped part. The cationic modification is carried out with a reactant dissolved in a solvent and having one or more amine, imine and/or amide groups.