Using film and foil to create a superior finish

Converting Today talks to Andy Kerr of API Foils for expert advice on overprinting, and then analyses some new developments in film that have emerged this year.

While decorative foiling can set a customer's packaging apart from others', overprinting helps to take it to the next level. If you want to delight your customer, then you need to understand the process and avoid the potential pitfalls. Andy Kerr, responsible for international technical support at API Foils, advises.

The multitonal effect of overprinting heightens and takes the already luxury feel of decorative foiling to another level. The design options available are boundless.

You can, for instance, use a variety of semitransparent inks to enhance the foiled image and, depending on the desired effect or the colour and structure of the substrate, exactly how creative you want to be is really up to you.

For an even greater multicoloured effect, textured stamping dies can create an almost holographic image by defracting light. This, plus the choice of colours on decorative foil, creates a high-end luxury feel that really does differentiate your customer's packaging.
When you step back and consider your options, you can offer your customers a number of possibilities. Packaging can be printed without foil, be foiled with print, have the foil completely covered with ink, or be foiled and partially covered with ink, leaving areas of foil exposed.

A good designer will look at the materials available, the colours, the hues and tones, the tactile effects and the decorative requirements of a product. They will then consider the best combination of materials and methods of decoration to enhance the purchaser's experience.

The challenge for the converter is to use the materials and equipment at their disposal, so that they can provide the means for customers to differentiate themselves from the competition and at the same time develop a reputation for producing a high-class product.

Avoiding the pitfalls of foil
While the design possibilities are almost endless, you must also consider the application process, as pitfalls can occur. There are three elements that you must consider and understand to get the best possible results.

To achieve this, it makes good business sense to use high-quality substrates and coatings and a good quality foil transfer process, be it a cold-foiling or a hot-foiling application. Since investment in printing and foiling equipment normally runs into millions of a company's budget, it makes even more sense to invest in the best materials as well, since they have a major bearing on the adhesion of the foil.

Being diligent, seeking advice from material suppliers and then ensuring compatibility of equipment and materials for the process goes a long way to producing a stunning product for the end user.

As stated earlier using the best combination of equipment and materials is critical to the end result and part of the process in achieving that is by minimising any 'edge flash'. This can happen when the pressure, temperature and make ready are not optimised to produce a clean, well-defined edge on a stamped image. The printed image of adhesive in the cold-foiling process and the stamping die in the hot process are also critical to the end result.

The adhesion of inks to the foil surface depends on the chemistry of the foil's release/lacquer and that of the resins in the overprinting inks. The inks must be suitable for printing on non-absorbent surfaces. Those most commonly used are UV-cured or dried by oxidation.

Our best advice is to contact your foil supplier for the most suitable foil grades, as well as the ink supplier for guidance about appropriate ink formulations.

In conclusion, overprinting decorative foiling allows designers and converters to create something truly spectacular, but such results are only possible if both the design and application processes are carefully considered.
The application process is relatively simple, but can catch out the unwary if it is not properly understood. It requires every element to work if you want to achieve the optimum finish.