It has been found, that when co-absorbing substances are added to intrinsic laser-absorbing bismuthoxide, the marking performance with a Nd.YAG-laser is improved or at least kept at the same level by reducing the costs. It is suspected, that the co-absorbing additive is not simply adding a contrast to the polymer by carbonizing the surrounding polymer but helping the bismuthoxide to couple the laser radiation and to ease the color change of this additive. This so found effect helps to cheapen the replacement of antimony trioxide and therewith have a safer and more sustainable solution for the current and future technology of laser marking.