Foil Stamping in a Rotary Press

Among the functions of any kind of packaging, attracting consumer's attention is one the most important. Among the various possibilities to decorate packaging, foil stamping rises above the others because it shines and gives an aspect of luxury and high quality to the product. For that reason it is very common to find foil stamping on wine labels, cosmetic products, etc.

There are two different ways of foil stamping in a rotary press. One is the traditional hot stamping process where heat is used to adhere the foil onto the substrate, and the other one is the cold stamping, an emerging process where the heat is not necessary.

Cold stamping is a process in which stamping foils are transferred to a substrate by means of a UV curable adhesive. The adhesive is applied to the substrate by means of a printing unit (offset or flexographic) and then the foil is laminated onto the substrate. This lamination passes through a UV curing lamp, and the adhesive is cured. At the end oh the process, the foil is stripped from the substrate. So, it means that for this kind of process we require a printing unit with UV curing and a laminating unit with unwind and rewind facility for the foil.

The cold stamping process does not require any stamping cylinder. A printing plate replaces this. It is easy to guess that the printing plate cost is much cheaper and much faster to produce than a stamping cylinder.

According to our experience, the stamping speed achieved using the cold process is higher than hot foil stamping. It is easy to reach speeds about 60-80 m/min or even more. With the hot process normal speeds are between 30-50 m/min and it is very important to have a skilled operator in hot stamping.

However, the hot process has some advantages over the cold stamping. The main one is the quality, especially on fine details. Edges are sharp and there is no filling in small details such as texts. In addition, hot foil has a good performance in all kind of substrates while the cold foil does not give a very high quality on rough substrates like antique papers used on wine labels.

Regarding the cold process, we found that the stamping quality is higher when the adhesive is applied with an offset instead of a flexographic printing unit. One of the reasons is because in the offset process we have a major control over the amount of adhesive applied onto the substrate. It means that we can adjust it across the web depending on the stamping design.

Rotatek offers both, cold and hot foil stamping units that can be fitted into the Rotatek rotary presses.