Cold and Hot Foil Stamping
Throughout my 40 years in the printing industry, I had read about hot foil stamping and had seen samples of the various foiling options. I had even seen the process in printing plants and on Internet videos.
As much as I liked the results, I was clear that foil stamping was an expensive process, given the need for metal die stamping rules to cut the foil. So I was pleased to recently learn about a foil application method called cold foil printing.
First of all, let’s discuss the original process. Hot foil stamping involves striking a ribbon of foil using pressure, heat, and a sharp metal rule to both cut out and apply the foil to the substrate. To achieve this effect, the printer uses an impact-based printing press such as a converted letterpress (in contrast to a non-impact offset press).
You may have seen embossed, foil stamped “starburst” patterns on certificates of appreciation or on dust jackets for books. The embossed foil has depth and texture, as well as reflectivity, and there are many foil options available from silver and gold to pearlescent (and even holographic).
You may also have seen foil stamping effects used for type applied to dark paper stocks (invitations, for instance), and for type applied to cloth hard-back book covers. Other uses for foil stamping include decorating annual reports, business cards, letterhead, pocket folders, and folding cartons (as well as other product packaging).
In contrast to the heat, pressure, and cutting-die method of hot foil stamping, there is a cold foil option that works as follows:
1. Using standard offset printing plates, an offset press applies adhesive to the substrate where the foil will adhere. (Therefore, there’s no need for a separate foil-stamping metal die.)
2. UV light cures the adhesive until it is just tacky but not completely dry.
3. A sheet of foil material is applied to the adhesive, and the glue on the image area adheres to the foil.
4. Foil not specifically attached to the adhesive is on a backing sheet and can easily be removed (wound up on a spool), leaving the image area covered in the foil material.
5. So, in essence, the foil is applied like an additional ink, and this reduces the overall cost of the foiling process by eliminating the need for metal dies. It also speeds up the foiling step, since all processes can be accomplished in-house by the printer (die making is a subcontracted, time-consuming as well as expensive, process).
6. The cold-foiling process lends itself to gradients and halftones, unlike traditional hot-foil stamping. (That is, hot foil designs need to be simpler: solids and text). You can even produce legible 5 pt. type (and larger) as well as hairline rules using cold foil, although your substrate must be very smooth (unlike hot foil stamping).
7. The foil image can then be varnished or otherwise coated for protection.
When would you use one process vs. the other?
1. My understanding from my research is that you would use cold foiling for large areas in product packaging, such as folding cartons for make-up or wine labels. If you’re just foil stamping a smaller portion of a product (like a starburst for a certificate of appreciation), hot-foil stamping may be a more economical option.
2. If you are producing a multi-level, embossed as well as foiled, surface (again, like a starburst for a certificate), you might choose hot foil stamping, since cold foiling is a flat-application that is not embossed. (Hot foil stamping even when not embossed provides a dimensionality that is absent in cold foiling. Subconsciously, this additional texture may be perceived as a more opulent or luxurious design treatment than the flatness of cold foil.)
3. If you’re using an uncoated press sheet (such as a dark felt paper for an invitation), and you’re applying lighter type and imagery for contrast, you would use hot foil stamping for the artwork, since cold foiling does not work well on textured, uncoated press sheets and is not as opaque as hot foil stamping.
4. You can easily print over dry cold foil. This is not necessarily the case for hot foil. So if you’re trying for a more colorful effect, you may want to choose a cold foil application over hot foil stamping.
5. If you can’t decide, you can even use both hot foil and cold foil on one product, benefiting from the strengths of each option.
What is Dry Offset?
Printers tend to be creative problem-solvers, coming up with unique ways to put ink on paper or other substrates. I recently read an article about a hybrid process called “dry offset.” It is not the same as waterless printing, which uses a layer of silicone rubber on printing plates to repel ink in non-image areas (in lieu of maintaining a balance between oil-based inks and water, as in traditional offset printing).
Dry offset uses relief plates (like flexographic and letterpress plates) to transfer an image to a press blanket and from the press blanket to a substrate. This technique is called “dry” offset because the dampening solution used in traditional offset printing is omitted from the process.
If you’re in the printing field as a designer (perhaps in a non-profit organization producing marketing collateral and books), you may not have heard about dry offset because it is primarily used for product decoration. More specifically, it’s great for printing on beverage cans and aerosol cans (such as those used for food and beauty products), as well as on flat plastic packaging.
All of the ink colors are printed at the same time (in register). Therefore, precision is essential to ensure that the relief plate offsets all colors of the image accurately onto a blanket and from the blanket onto a (usually) curved substrate like a metal cylinder.
Along with the need to maintain precise register during the simultaneous printing of all ink colors is the challenge of using entirely opaque inks. In contrast to 4-color process printing with transparent inks laid over one another to simulate different colors, for dry offset you must use PMS spot color inks that precisely abut to one another on the final printed substrate.
It’s seems like a daunting task to make all of this work precisely and successfully, but you can find online videos that show dry offset printing in action. One of the videos I found showed flat printing plates applying all colors at once to blankets on cylindrical rollers. As white plastic paint drums were brought into place, the inked blanket rollers spun the plastic paint cans around at the same time as they deposited colorful images that completely covered each plastic drum. And all of this was happening at lightning speed.
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]