Gill Loubser (GL): First of all, how does hot foil stamping work? And what’s different about cold foiling?
Mike King (MK): Hot foil stamping is accomplished on an off-line stamping machine using a metal die engraved with the desired image. Under high pressure and at high temperatures, the die compresses against the foil, causing the foil to adhere to the substrate, resulting in a highly reflective image with a bright, dense metallic appearance, and a rich, flat look.
Cold foiling is accomplished inline on a litho, flexo or gravure press, either sheetfed or web. In the litho version, for instance, a standard printing plate is used. An image is printed on a coated substrate using UV-curable cold foil adhesive or a conventional adhesive. The foil passes through the nip with the adhesive-printed substrate, and wherever there’s adhesive, the foil sticks. The foil carrier is then rewound or extracted and the substrate continues its path through the printing process where overprinting on cold foil creates various colours.
GL: What are the main considerations when choosing between the two processes?
MK: A prime consideration is the size of the foiling area. With inline cold foiling, if the area on the sheet to be foiled is small and doesn’t make use of the entire width of the foil ribbon, there can be excessive foil waste. On the other hand, hot foil stamping allows the foil ribbon to be precisely indexed in small increments, maximising the use of the entire ribbon. To reduce cold foil waste, we have created two options. The first is the ability to run narrow cold foil webs from 50mm in any combination of web sizes at one time. The other is the patented Eagle Foil Sync that allows the most economical use of cold foil.
Apart from the size of the image area, other considerations are the number of images on one sheet, and the run length. It’s also vital to look closely at all the variables (including makeready time, plus the cost of dies, printing plates and foil).
But perhaps most important is whether a customer will accept the reflective brilliance of cold foil or demand hot foil.
GL: What about substrates? Are there any restrictions on what can (or cannot) be used in conjunction with cold foiling?
MK: Certain substrates such as uncoated stocks can pose a challenge for cold foil. During the cold foiling process, a layer of adhesive is applied to the sheet. Uncoated stocks tend to absorb the glue, resulting in less adhesive for the foil to adhere to, which can lead to uneven surfaces, rough edges and foil flaking.
Hot foil stamping provides more latitude with substrate types since foil is applied to the sheet by heat-activated adhesive.
GL: In your view, what are the primary advantages to be gained by inline application?
MK: The inline process not only eliminates the need for off-line hot foil stamping but also means that inks, varnishes and coatings can be applied inline over the cold foil. This saves an additional press pass following hot foil stamping.
Additionally, while makeready times for hot foiling can take as much as eight hours (for instance using 12 dies), the average makeready time for cold foiling is under 30 minutes.
GL: Is cold foil available in the same range of colours as hot stamping foil?
MK: The whole idea behind cold foiling is you don’t need to stock numerous foil colours. Using CMYK or PMS colours, any colour of the rainbow can be created. If a customer doesn’t like the colour, it can be simply changed on the press, because the colour comes from the overprint on the foil.
With hot stamping, the entire process comes to a halt until the exact colour foil is in stock.
Another consideration here is inventory. Many printers have large stocks of unused hot stamping foil, but using cold foil requires minimal inventory, as 95% of the work is done in silver foil.
GL: How close is cold foil quality getting to the traditional quality expected from hot stamping foil?
MK: It’s getting closer to the brilliance of hot foil but isn’t quite there yet. However, there’s a place for both processes and cold foil is making steady advances. While hot foil has a flat and rich look, cold foil is more flexible – it allows the printer to create effects that cannot be achieved in other ways. Cold foil is also available in gold and holographic patterns.
GL: How are printers best able to make the choice? What questions should they ask?
MK: When choosing between hot and cold foiling, it’s important to keep the end game in mind. It’s best to start with a product’s particular needs and then find a match based on how well the capabilities of each technology align with the product.
Some questions that need to be answered are these:
- What’s best for the application? You need to understand the product and its target market.
- What’s the budget? While budget shouldn’t be the first consideration, it can often limit a printer to a particular solution.
- What substrate is being used? Again, the packaging’s substrate may determine the preferred method of foiling. Certain substrates only work with hot foil, while others are best with cold foil.
- What type of look is required? In the past, hot foil provided more options, but today cold foil gives an increasing number of options. Even cold foil brilliance can be as much as 90% of hot foil brilliance when certain techniques are used. The particular properties of cold foil are fine type and line details, gradient effects and halftones – and all in perfect register!
[Ed’s note: In South Africa, the team at Alliance Machinery has been keeping up to date with developments and progress in cold foiling, in particular watching Eagle Systems’ success with cold foil retrofit systems on sheetfed offset machines. According to Alliance Machinery’s Bradley Bate, it’s clear that this is a growing global trend. Contact Alliance Machinery for further information or visit www.thefoilexperts.com.]