Method for treating a plastic part, which comprises a surface, comprising the steps: A) irradiating at least a part of the surface with a treatment radiation to obtain a modified surface area, the modified surface area being capable of absorbing a heating radiation to an extent greater than the unmodified surface area, and B) irradiating the modified surface area with the heating radiation at least in a section so that the plastic part is heated and softened in a region defined by the irradiated section of the modified surface area.
