A process for producing an optical effect layer on a substrate, said process comprising the steps of: a) applying onto a substrate surface a coating composition comprising platelet-shaped magnetic or magnetizable pigment particles so as to form a coating layer on said substrate, said coating composition being in a first state, b) placing the substrate carrying the coating layer on a first magnetic-field-generating device providing a first magnetic field vector component, said first magnetic-field-generating device being mounted on a transferring device thereby subjecting the platelet-shaped magnetic or magnetisable pigment particles to said first magnetic field vector component, concomitantly moving said substrate carrying the coating layer and said first magnetic-field-generating device in the vicinity of a static second magnetic-field-generating device, said second magnetic-field-generating device providing a second magnetic field vector component thereby subjecting the platelet-shaped magnetic or magnetisable pigment particles to a time-dependent resultant magnetic field formed by the first and second magnetic field vector components so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, wherein the ratio of the magnetic flux density of the first magnetic-field-generating device and the magnetic flux density of the second magnetic-field-generating device is less than about 4.0, preferably less than about 1.9 and more preferably between about 1.5 and about 0.5; and c) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations. a) applying onto a substrate surface a coating composition comprising platelet-shaped magnetic or magnetizable pigment particles so as to form a coating layer on said substrate, said coating composition being in a first state, b) placing the substrate carrying the coating layer on a first magnetic-field-generating device providing a first magnetic field vector component, said first magnetic-field-generating device being mounted on a transferring device thereby subjecting the platelet-shaped magnetic or magnetisable pigment particles to said first magnetic field vector component, concomitantly moving said substrate carrying the coating layer and said first magnetic-field-generating device in the vicinity of a static second magnetic-field-generating device, said second magnetic-field-generating device providing a second magnetic field vector component thereby subjecting the platelet-shaped magnetic or magnetisable pigment particles to a time-dependent resultant magnetic field formed by the first and second magnetic field vector components so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, wherein the ratio of the magnetic flux density of the first magnetic-field-generating device and the magnetic flux density of the second magnetic-field-generating device is less than about 4.0, preferably less than about 1.9 and more preferably between about 1.5 and about 0.5; and concomitantly moving said substrate carrying the coating layer and said first magnetic-field-generating device in the vicinity of a static second magnetic-field-generating device, said second magnetic-field-generating device providing a second magnetic field vector component thereby subjecting the platelet-shaped magnetic or magnetisable pigment particles to a time-dependent resultant magnetic field formed by the first and second magnetic field vector components so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, wherein the ratio of the magnetic flux density of the first magnetic-field-generating device and the magnetic flux density of the second magnetic-field-generating device is less than about 4.0, preferably less than about 1.9 and more preferably between about 1.5 and about 0.5; and c) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations.