What is Cold Foil Application?
Cold Foiling is the application a metallic foil to a sheet on a Printing press.Two towers of a lithographic press are used. On the first the adhesive is printed onto the substrate with a standard lithographic plate in the pattern desired.
On the second tower the cold foil is passed between the blanket cylinder and the impression cylinder.
As the sheet arrives at the second tower it comes into contact with the foil and they are pressed together through the nip between the cylinders where the foil adheres to the adhesive in the printed pattern and is transferred to the sheet, the remaining foil stays on the polyester and is rewound.
Cold foil consists of 5 layers of material, however, unlike hot foil, the release coat reacts to sheer and not heat and the hot melt adhesive on the back of hot foil is replaced with a lacquer coat which has an affinity for cold foil adhesive.
Cold foil adhesives are available as conventional or UV formulations. Cold foil adhesive has more in common with ink than glue in its constitution and applied to the substrate in the same manner as ink through the normal ink train.
The foil is overprinted in the remaining units of the press to produce the desired finished effect. With cold foil the color now comes from the process and not the material and so predominantly silver foil is used.
Either conventional printing or UV printing can be used and in both cases it is necessary to coat for drying, UV dries or cures instantaneously while conventional ink requires standing time.