Folding cartons and labels are often printed on aluminized papers or aluminum-coated cardboards. Since it is difficult and time-consuming for standard inks to penetrate these non-absorbent printing materials, this can lead to problems with drying and adhesion. Consequently, either UV inks, special conventional foil inks or, depending on the press configuration, a mixed mode of operation can be used for such applications.
Metallic colors can be produced by printing transparent offset inks on the metallized material. On the adjacent bottle labels, for example, a gold color is achieved by the silver printing stock shining through a transparent yellow. An opaque white is applied where the printing stock's metallic gloss should not show on the motif. This can be achieved using either an offset unit or a coating unit.
The labels shown in the picture for example were printed on aluminized label paper using a Speedmaster with Duo configuration. The first step is to spot apply a UV flexographic opaque white in the coating unit in front of the offset units and then dry it completely using UV interdeck dryers. Foil inks that dry in the conventional way are used in the offset printing units. A dispersion coating forms the final, protective layer. Full-area application via a blanket is followed by IR and hot-air drying.