Inside Finishing Technology Focus
November-December 2006
The cold foil process is no newcomer to the industry of glitz and shine; in fact, it’s been around in the rotary, narrow-web industry for quite some time. However, like most technologies, the process has become more stable as the technical know-how, equipment, and materials utilized have become more sophisticated. Advancements in consistency, adhesion, substrate compatibility, and speed have opened doors to a broader range of foil applications across a variety of markets – markets that otherwise may never have considered foil a viable option.
The growth and technological advancement of the cold foil process, particularly with recent developments in the sheet-fed lithography arena, have left many wondering how the process works, for what applications is it best suited, and in what markets is it penetrating?
Flexography Present day, primarily label converters with rotary web-fed flexographic UV technology use the cold foil process. “They tend to be more focused on the prime label market,” states VP of Sales and Marketing Bob Witte, API Foils. “These labels usually contain high-end designs for health and beauty aid products that often use foil stamping as a quality enhancement.”
In the early days of cold foiling, cationic UV adhesives were used in the process (and before that, water- and solvent-based adhesives). This required a UV dryer to activate the adhesive and make it tacky just prior to the introduction of the foil. “This method proved inconsistent since the level of tackiness achieved varied to such a degree that the foil print quality was erratic,” explains Witte. “It was not until the introduction of free radical UV adhesives, along with the technique of activating the adhesive through the foil after it has been nipped, that the process became more robust and accepted as a bona fide production method.”
Today, rotary web-fed cold foiling requires only one unit and is very versatile in nature, with the ability to be applied before the printing, after the printing, and in any design configuration desired. The cold foiling process has several advantages over hot in the web-fed format. The primary benefit is speed. In most cases, cold foiling runs twice as fast as hot foiling. This is because the UV-activated adhesive allows the foil to adhere much faster than a heat-activated foil. “We (API) have several customers that do both hot and cold rotary foiling and are achieving speeds of 400 feet per minute with cold as opposed to only 200 feet per minute with hot,” states Witte. “Although many people feel that hot foil gives a higher quality and sharper appearance, cold foiling has established itself as an excellent medium for overprintable and high volume label applications.”
Progressing beyond the cold foil retrofit units, flexographic machine manufacturers such as Mark Andy/Comco, Nilpeter, and Gallus have integrated the cold foil process directly into their flexo printing presses. “Some systems, such as the Mark Andy XP5000, come equipped with a cold foil unit that can be slid into any print station, thereby offering even greater flexibility,” states Michael Rivera, vice president of sales – cold foil division with AMAGIC Foils.
Lithography Beyond the flexographic arena, recent innovations in utilizing the cold foil process with sheet-fed lithography are entering the market as an alternative to metallized board. This offset technology utilizes a tacky adhesive that is applied in the first printing head. The foil is then nipped to the adhesive and the carrier stripped away leaving the foil covering the board where required. “Specially formulated foils have been designed to work with this system,” Witte explains. “These foils also must be overprintable, since the subsequent printing heads apply the ink on top of the foil all in one system.” Heidelberg and MAN Roland have developed cold foil equipment for this process, which are specific to their own presses, while OFT Technology has developed the Foiltone™ cold foil system (distributed in the U.S. and Canada by American International Machinery) that retrofits to most printing presses.
The ROLAND InlineFoiler Prindor, winner of the PIA/GATF 2006 InterTech Award, can be installed on any recent vintage ROLAND 700 press – MAN Roland’s 41-inch model. Heidelberg’s FoilStar™ modular cold foil technology is utilized with the Speedmaster® CD74 and Speedmaster® CD102 printing presses. And as previously mentioned, OFT Technology’s Foiltone™ system will retrofit to most printing presses and can utilize both conventional and UV-curable adhesives. As with all cold foil technology, no stamping dies are required and makeready times are greatly reduced compared to conventional hot foil stamping processes.
All three systems are installed in the first and second printing units of the press, and can be used for regular offset printing when the cold foil units are not engaged. In the first printing unit, the areas of the substrate where foil is to be applied are printed with a special adhesive ink via the inking roller system using a conventional printing plate. In the second printing unit, the blanket cylinder presses the foil onto the areas of the sheet covered with the adhesive ink. The unused foil remains on the carrier layer, which is rewound by the rewinding station, typically mounted above the third printing unit. In this printing unit and subsequent ones, the areas of the sheet not covered with foil can be printed with absorption-drying inks. Lithographic printing blankets are manufactured with differing degrees of hardness (compression) and the choice of blanket will have an effect on the finished foil look. “If a textured material is being used, it would be normal to choose a blanket with a lower compression than one which may be chosen to foil onto a hard surface, such as plastics or a cast coated board,” explains Sales Director John Hopkinson, OFT Technology Ltd. “The half tone effect of foil also is partly determined by blanket compression in conjunction with the smoothness of the substrate.”
Cold Foil – Attributes and Limitations The application of cold foil on the lithographic sheet-fed press should be viewed as an extension of the use of foil to embellish the printed surface. Applications exist that will always be hot foil, a middle area which could be either hot or cold, and a new area which is most definitely cold foil. The main difference between the two processes from a technical point of view is that hot foil is stamped into a surface while cold foil is laid onto a surface. “This principal difference does lead to a different look, the beauty of which is in the eye of the beholder, or more factually, in the eye of the designer – as this process puts another tool at the designer’s disposal,” states Hopkinson.
The look that is attainable with hot foil is very well established and recognized. The look that is attainable with the litho application of cold foil is less understood; however, many of the same printing effects can be achieved with the cold foil process as with ink.
The ability to produce large, solid areas of foil with no gassing issues; small, reversed out areas of type as thin as .05mm in thickness; and the ability to produce foiled half tones are definite attributes of the cold foil process. Furthermore, textured substrates (such as a linen stock) retain their texture after foiling, thereby offering further design opportunities. Printing multiple colors of foil at the same time, decreasing registration issues, and allowing for the use of substrates not suitable for hot stamping are additional advantages.
“More and more (flexo) packaging applications are requiring thinner films that tend to be heat sensitive. Applying heat to these substrates through the hot stamping process can cause the material to distort,” Witte explains. “The cold foiling method not only allows thin films to be foil stamped but also, forms a basis that will let the foil actually shrink or expand to a small degree without cracking.”
Additionally, running speeds, stamping die costs, and makeready times are all decreased or eliminated with the cold foil process. “Cost is a key factor,” states Witte. “Since adhesive is applied with an inexpensive polymer plate, the cost to changeover to multiple print formats is minimal. The opposite is true with hot foil. The cost of rotary tooling is relatively very expensive and can be prohibitive.”
On the other side of the coin, cold foiling on sheet-fed presses has its limitations and is not suitable for many applications where hot foil stamping would excel. First of all, foil usage is one-to-one with the substrate. In other words, the foil pull must run the same length of the substrate and cannot be indexed as with the hot foil process. This would not be an issue if the image(s) to be foiled, for example, either occupied most of the sheet or at least a large, solid portion of it. However, if the foiled image(s) is positioned only at the top or bottom of the sheet, or perhaps both, the hot foil stamping process would be a much better option and more cost effective.
Second, the cold foil process is more suitable for coated stocks than dry, porous stocks. And although foil companies continue to make improvements to the cold foil construction so that the technology will work on a wide variety of substrates, including porous paper stocks, the hot stamping process far excels on these types of substrates. Third, the cold foil process is a flat application only and cannot be utilized with combination stamping and embossing.
Finally, the brilliance achieved through the hot foil stamping process is like none other. For many high-end applications, this may be an important factor. However the key point to be made about the cold foil process is that it is not replacing the hot foil process but instead, is being utilized to penetrate markets where previously, foil was not a viable option. “Yes, there can be a difference in brilliance,” explains Rivera. “But when you’re foiling thousands of labels for shampoo bottles, people don’t know the difference. All they know is they now have the ability to apply foil to their product in a cost effective manner.”
Foil Growth – A Win/Win Situation The cold foil process also has made its way into digital technology with manufacturers such as Omega and Rotoflex, where cold foiling can be added in the converting end of the press. However, as Rivera points out, “These processes are limited in the types of stock which can be utilized (namely film stocks and not laser stocks), as well as the size of the runs (under 10,000 labels). Anything greater would not be cost effective.”
A look at the cold foil movement today shows the greatest concentration in the narrow web flexo label market. “Tomorrow, add narrow web flexo small cartons,” predicts John Thoma, Kurz Transfer Products. “Down the road, we will start to see more and more sheet-fed operations for greeting cards and folding cartons. Eventually, it will even make it onto in-line hi-speed rotogravure printing, such as gift wrap or cigarette cartons.”
So, what does this mean for the foil stamping industry at large? “Greater exposure!” exclaims Jeff Peterson, executive director of the Foil Stamping and Embossing Association (FSEA). “An increase in foiled product in the marketplace equates to greater visibility overall. And if one product has foil, why can’t another?” Once hooked on the eye-catching draw of foil, it is hard to go back.
Witte concurs, “As a foil manufacturer selling to both the hot and cold foil markets, I have not sold cold foil to one customer for an application that otherwise would have been hot foil stamped. The cold foil process should not be viewed as a replacement to the hot foil process but more accurately, as an opportunity to expand the use of foil into markets otherwise untouchable by foil.”
Education starts in the marketplace. If designers see foiled product on the shelf, they become curious and start to ask questions. Eventually, they become more familiar with the process and in turn, become more comfortable with designing with foil. “So whether utilizing the cold or hot foil process, the news is good for the industry as a whole,” concludes Peterson. “It’s a win/win situation for all.”