A method for producing an optical effect layer (OEL), said OEL comprising a motif made of at least two areas made of a single applied and cured layer comprising non-spherical magnetic or magnetizable pigment particles and exhibiting one or more indicia on a substrate, the method comprising the steps of:
- a) applying on a substrate surface a radically radiation curable coating composition comprising the non-spherical magnetic or magnetizable pigment particles and one or more photo-reactive compounds not absorbing in a range from about 375 nm to about 470 nm, said radically radiation curable coating composition being in a first, liquid state so as to form a coating layer;
- b) subsequently to step a), applying a top coating composition at least partially on top of the coating layer, wherein said top coating composition is applied in the form of one or more indicia and wherein said top coating composition is nonmagnetic and comprises one or more compounds absorbing in the range from about 375 nm to about 470 nm, and wherein the top coating composition and the coating layer are applied on each other in a wet-on-wet state,
- c) partially simultaneously with or subsequently to step b), at least partially curing the one or more indicia and the one or more areas of the coating layer below said one or more indicia with a LED curing unit emitting between 375 nm and 470 nm, thereby fixing an orientation of the non-spherical magnetic or magnetizable pigment particles in the one or more areas of the coating layer below said one or more indicia;
- d) subsequently to step c), exposing the coating layer to a magnetic field of a magnetic-field generating device so as to orient at least a part of the non-spherical magnetic or magnetizable pigment particles;
- and
- e) partially simultaneously with or subsequently to step d), at least partially curing the coating layer with a curing unit at least emitting between 250 nm and 320 nm,
- wherein the radically radiation curable coating composition and the top coating composition are radically curable compositions, and
- wherein the one or more photo-reactive compounds not absorbing in the range from about 375 nm to about 470 nm of the radically radiation curable coating composition of step a) and the one or more compounds absorbing in the range from about 375 nm to about 470 nm of the top curable coating composition of step b) are selected according to one of the following combinations:
- i) the one or more photo-reactive compounds of the radically radiation curable coating composition of step a) are alpha-hydroxyketone compounds and the one or more compounds of the top curable coating composition of step b) are selected from the group consisting of acyl phosphine oxide compounds, alpha-amino-ketone compounds, mixtures of one or more benzophenone compounds and one or more amine compounds, glyoxylate compounds, benzyl ketal compounds, oxime ester compounds, titanocene compounds, mixtures of one or more thioxanthone compounds and one or more amine compounds, mixtures of one or more coumarin compounds and one or more amine compounds, mixtures of one or more camphorquinone compounds and one or more amine compounds;
- and mixtures thereof;
- ii) the one or more photo-reactive compounds of the radically radiation curable coating composition of step a) are mixtures of one or more benzophenone compounds different from the benzophenone compounds of the top curable coating composition of step b) and one or more amine compounds and the one or more compounds of the top curable coating composition of step b) are selected from the group consisting of acyl phosphine oxide compounds, alpha-amino-ketone compounds, benzophenone compounds different from the benzophenone of the radically radiation curable coating composition of step a), glyoxylate compounds, benzyl ketal compounds, oxime ester compounds, titanocene compounds, thioxanthone compounds, coumarin compounds, camphorquinone compounds, and mixtures thereof, or
- iii) the one or more photo-reactive compounds of the radically radiation curable coating composition of step a) are benzyl ketal compounds different from the benzyl ketal compounds of the top curable coating composition of step b) and the one or more compounds of the top curable coating composition of step b) are selected from the group consisting of acyl phosphine oxide compounds, alpha-amino-ketone compounds, mixtures of one or more benzophenone compounds and one or more amine compounds, glyoxylate compounds, benzyl ketal compounds different from the benzyl ketal compounds of the top curable coating composition of step a), oxime ester compounds, titanocene compounds, mixtures of one or more thioxanthone compounds and one or more amine compounds, mixtures of one or more coumarin compounds and one or more amine compounds, mixtures of one or more camphorquinone compounds and one or more amine compounds, and mixtures thereof.