Adhesives for Offset Cold Foil Use

Increasingly popular, metallic effects can be found on magazine covers, cosmetic boxes, wine labels and countless other applications—drawing the eye of consumers. Difficult to fake and impossible to copy, metallics have also found a role in enhancing packaging and product security.

A variety of approaches can be used: hot and cold foil stamping, metallic inks and ink matching systems, metallized papers. Recently, cold foiling applied by offset press has begun to catch on. (The process was demonstrated on Graphic Arts Monthly's July 06 issue.)

MAN Roland has placed two of its InLine Foiler Prindor cold-foiling units on presses at VistaPrint, Windsor, ON, with another reportedly scheduled for start-up at a Chicago unit of Taylor Corp. The presses deliver foiled runs at up to 9,000 sheets per hour. (The press manufacturer offers a Technic and Design Guide, written for printers and print buyers, about the process.)

Heidelberg has made the first installations of its FoilStar foilers in Europe. OFT Technology also offers its Foiltone process (available from American International Machinery), which can be outfitted on various offset presses.

All these offerings operate along similar lines: A specialized, oil-based adhesive that behaves much like conventional printing ink is applied through a lithographic plate; a special cold foil on a carrier base is fed from a foil transfer device in the next printing unit whereby, in the printing nip zone, the transferable foil layer comes into contact with the areas of the substrate printed with glue. There, the foil is delaminated from its polyester backing and the metallic color transfers to the glue areas.

One of the advantages of cold-foil printing is the ease with which the special surfaces can be overprinted, creating a limitless array of colors. For the inside of GAM's roll-fold cover last July, for example, MAN Roland started with silver foil, then overprinted it to create a rich, golden tone.

To print on top of the foil, adhesion of the inks and lacquers is essential. Tests conducted by Leonhard Kurz GmbH & Co., a leading manufacturer of foil and hot stamping technology, indicate that UV is ideal for this purpose.

XSYS Print Solutions has formulated specialty inks compatible for use in the cold-foil printing process. Its water-based and UV-curable inks can be used under the cold foil image or printed on top of it, blending with the underlying foil to create unique colorations.

There are challenges in terms of the ink. Developing a suitable adhesive is crucial, and work in UV curing is promising. Depending on the application, these adhesives may have to meet food packaging guidelines.

The ability to add more value to customer products using metallics is an important tool for printers. Inline cold-foil systems are an approach that seems to be gaining headway in the sheetfed market.