What to consider about the different processes for embellishing printed pieces.
It wasn’t too many years ago that when a brand owner or other business wanted to add foil to its package, business card, direct mailer, or other printed materials, the only real option was foil stamping. In this process, a die (engraving) is used with heat and pressure to stamp the foiled image with hot stamping foil. Although this process is still the best — and most popular — choice for many applications, there are now several more processes available to add a metallic embellishment to printed materials.
Hot Foil Stamping (Hot Transfer Metallic)
Foil stamping is by far the most versatile process when applying foil, meaning it has a much broader range of paper stocks it can work on and the broadest range of foil colors and adhesives. It provides the ability to create finished, decorated looks that other foil processes cannot, including foil and embossing in one pass and refractive (micro-etched) patterns in the surface of the foil. It also provides the greatest array of equipment choices in the marketplace to foil stamp different sized sheets and substrate choices.
The disadvantage of hot foil is the cost of the tooling needed to apply the foil (i.e., the foil stamping dies, or engravings). (With both cold and digital foil processes, there are virtually no tooling costs.) However, the tooling cost is relative to the size of the job. If the run length is small, it can be a significant cost. Hot foil stamping is also a secondary process once a sheet is printed. Th is can add time to the job and, of course, add costs.
Cold Foil Transfer (Cold Transfer Metallic)
Cold foil transfer for sheet-fed applications is not new by any means, but it has become much more popular for many applications in recent years. This is due to better foil products that run much faster and keep a metallic sheen when they are applied. Improved adhesives and improved technology with cold foil transfer machinery has also been a part of its growth in recent years.
The most prevalent advantage of cold foil transfer is the elimination of a secondary process. The cold foil can be applied in the first two stations of an offset press, and then the additional stations on the press can apply CMYK over the top of the foil, creating virtually any color under the rainbow. Cold foil also does not have to utilize more expensive tooling (dies). It is an excellent choice for projects where there is significant foil coverage. In addition, cold foil transfer is a great alternative to foil-laminated board, where the metallic finish covers the entire sheet. In most cases, when using a foil-laminated board, white opaque ink is needed for certain areas on the sheet, especially with folding carton work. Not only is this an additional station, with a printing plate needed on the press, but white ink is notorious for being difficult to work with. Cold foil transfer allows the areas that need to be white to be “knocked out” of the foil design, eliminating the need to use any type of white ink.
From a disadvantage standpoint, cold foil transfer does not provide the full versatility of hot foil stamping as it relates to paper stocks. Although there has been some success recently with cold foil on uncoated stocks, it is most effective on coated papers. Cold foil is also not usually the best choice when the foil is being used in only certain areas of a design. Because the foil is running through the press at high speeds, there is less control of the foil. If the design does not require a large usage of foil, hot foil stamping may be a better choice.
Both hot foil and cold foil transfer processes are better choices for medium-to-larger-sized runs, mainly due to the setup time with cold foil and the tooling costs associated with hot foil projects. Smaller-sized runs, on the other hand, are often better suited for digitally applied foil.
Digital Foiling (Digital Transfer Metallic)
There are two processes that are identified as digital foiling, which has caused some confusion in the industry. There is a foil process that uses printed toner/ink as the adhesive for the foil, and a process that uses an inkjet-applied polymer as the adhesive. The Foil & Specialty Effects Association’s (FSEA’s) “Foil Cheat Sheet” guide that has been produced along with PaperSpecs identifies the two processes as toner-based digital foiling and polymer-based digital foiling.
Toner-Based Digital Foiling
This is a simple two- or three-step process utilizing a rich black toner or ink from a digital printing press as the adhesive, and then uses a heated lamination process that adheres the foil to where the toner/ink is printed. This process is often referred to as “sleeking.”
A key advantage of this process is the lack of any type of tooling or dies needed to create the foil image, making it a great choice for shorter runs or prototypes. Because a digital printer can be used to print out the images that will include foil, every sheet can be personalized or include different information in foil without adding costs. Short-run personalized invitations or gift cards are a great application for toner-based digital foiling. In addition, when using a silver metallic foil, the foiled sheet can be sent back through a digital printing press where all types of metallic hues can be created by printing over the top of the foil. There are both extremely simple, inexpensive machines for creating a toner-based digital foil product, and more sophisticated machines for short production runs.
Toner-based digital foiling’s disadvantage is that it is not a feasible option for larger runs of foil. Because it takes multiple steps to create, it is best suited for shorter runs. It also is limited to mostly coated stocks or stocks specifically used for digital applications.
Polymer-Based Digital Foiling
There are specific machines on the market today that can apply a polymer through an inkjet process to a printed sheet, and the foil adheres to the areas where the polymer is applied. Adding a thicker layer of adhesive also allows for the foil to be raised above the paper level, providing an embossed look to the foiled image. Special sensors on the digital decorating inkjet press can ensure registration of the print and polymer adhesives. There are systems in the marketplace that can apply the polymer and foil in one pass, and others where the polymer is applied, and then the foil is laminated in a process similar to toner-based digital foiling.
One advantage: This process is the same as toner-based digital foiling where there are no dies or plates needed to apply the foil — it is all done through an inkjet process. As with the toner-based process, it allows for personalization using foil, an option that is not feasible with hot or cold foil processes. Another advantage of polymer-based digital foiling is that a clear polymer (coating) can be applied over the foil or in other portions of the printed piece in a separate pass, adding specialty spot coatings and foil for one design that can create spectacular looks to all types of printed materials.
However, a disadvantage with polymer-based digital foiling is that it is more ideal for small-to-medium-sized runs. It produces spectacular work, but it is suited for targeted, specific applications. It is not set up for large runs of products, such as folding cartons and labels, or extremely large runs of direct mail. This type of foil decorating is also not suited for applying large areas of foil due to how the adhesive is applied (digital inkjet). Because of this, it is not commonly overprinted with four-color process. And, as with toner-based digital foiling, it is limited to coated stocks or special stocks.
There are still many applications, especially with folding cartons, where foil laminate or foil transfer paper/board is used. Foil-laminated board is used for very large runs with heavy coverage of a metallic finish. The obvious advantage of using a foil-laminated substrate is the ability to create the needed metallic finish in one pass on an off set press without the use of a retrofitted cold foil unit or having the sheet foil stamped with a separate process. This can provide cost savings for very large runs where the metallic finish is used throughout the design of a carton or label.
However, there are several drawbacks to using a foil-laminated substrate. The first is the cost of the material; it can become quite expensive. The ability of cold foiling in-line on more standard SBS stock for heavy coverage or foil stamping in a second pass, when there are specific areas only for the metallic finish, can be much more cost effective, especially in medium to large runs.
As stated earlier, when using a foil substrate, there are usually areas that still need to have a white background, especially on cartons and labels. In those cases, white opaque ink must be applied, which means a separate station on the printing press to apply it, in addition to the aforementioned difficulty working with this ink, and challenges it can cause on press.
Last, but certainly not least, is the sustainability issue with foil-laminated substrates. FSEA has invested in two separate studies and will be conducting more in the future that demonstrate that transfer foil decorated paper and board do not create problems in the recycling/repulping of paper and/or board in a common repulping process. This includes transfer hot foil, cold foil, and digital foil processes. It does not include foil-laminated
products, where the plastic film is included with the metallic finish. This is a key difference between the processes, and must be considered when determining which metallic decorating process should be used. However, it is worth noting that there are sheets on the market that are transfer metallic sheets. With these sheets, the plastic film is not laminated with the metallic, and is transferred to the sheet as it is with hot, cold, or digital foil.
It is clear that there are now several choices when considering adding a metallic embellishment to a printed sheet. There are advantages with each type of technology, and the different processes fit specific applications. The growth of digital and cold foil technologies has expanded metallics’ use throughout the printing industry and helped advance the overall use of hot, cold, and digital foil applications.
Jeff Peterson is the executive director of the Foil & Specialty Effects Association (FSEA). For further information on FSEA, including details on its Foil Cheat Sheet and its study on the Repulpability of Foil Decorated Paper/Board, visit fsea.com.