The development of cold foil stamping technology has made it possible for printers to produce more intricate and durable products. Cold foil has taken an important place in the printing of stamping foil. Cold foil combines the advantages of traditional printing and laminating technology and is simple to operate. Adding some ancillary equipment to the printing press used by the printer can be used for cold foil stamping, creating a distinctive effect without sacrificing quality or craftsmanship and will reduce the production cost. This post will summarize what we know about cold foil stamping, and if you need a high-quality cold foil for your project, pls click here to check out more.
The difference between hot foil and cold foil
The working principle and process flow of cold foil stamping differ from traditional hot foil stamping. The hot foil stamping uses the foil pre-coated with hot melt adhesive on the back, and relies on the pressure of the hot roller to melt the adhesive when stamping to achieve aluminum foil transfer.
And cold foil stamping uses special anodized aluminum, the back side without adhesive, and the adhesive is applied directly to the decorated location during printing. And it will use the new cold lamination technology to transfer the cold foil.
The cold foil stamping solves the process problems that are difficult to solve in hot stamping and avoids pollution caused by making stamping plates. This new method also saves a lot of energy.
Cold Stamping Process
When cold stamping, the cold foil will be in contact with the adhesive, and under its action, the cold foil will be attached to the surface of the substrate material. You can check the detailed process below:
First printing UV ink, after drying and under the action of a pair of metal rollers, the ink needs to be stamped on the surface of the unique printing adhesive – UV adhesive solvent. After printing, the water in the adhesive will be removed to a certain degree by the UV curing machine, forming a skinny layer of high viscosity pressure-sensitive adhesive for stamping.
Then the cold foil is firmly attached to the substrate material by applying pressure. Finally, the part of the cold foil that needs to be transferred comes to the print’s surface to achieve cold foil printing. The foil pattern on the surface of this print is delicate and must be protected. To do so, we either varnish or laminate it before doing other processes like cutting sheets.
The advantages of Cold Foil Stamping
Cold foil printing involves transferring foil to a substrate using glue. Compared to the traditional hot foil stamping process, cold foil stamping technology has the following advantages:
Fast printing speed & Short production time:
Cold foil stamping speed can reach 50 ~ 60 m / min, while the traditional general round stamping speed is only 20 ~ 30 m / min.
Wide range of material applications
Many materials, such as heat-sensitive paper and some film materials, can operate with cold foil.
High printing precision, good anti-counterfeiting effect
Compared with traditional hot stamping, cold stamping uses printing alignment due to its high accuracy of overprint alignment. Therefore, cold foil can combine with a hologram, transparent laser material, or other anti-counterfeiting technologies to highlight changes in printing design. It can produce the effect of metallic ink to achieve sound anti-counterfeiting results in printing valuable securities, packaging decoration, etc.
Save cost
Since cold foil stamping uses general flexographic plates instead of expensive metal plate rollers, so will save the cost of making the metal plate. And without the heating roller can reduce energy consumption. Overall, cold foil stamping costs about one-tenth of conventional hot foil stamping and can be suitable for small-lot production. In addition, without
Can take full advantage of original printing machine
Cold foil stamping technology for printing self-adhesive materials on narrow web rotary printing presses only needs to attach some devices to the original equipment. In addition, front-end printing can combine with cold foil stamping, so one machine can complete, significantly improving production efficiency.
ECO-Friendly
Since cold foil stamping does not require metal plate production and eliminates the chemical etching process, it reduces pollution and benefits environmental protection.
Printing Processes
Cold foil stamping can be widely applied to various printing industries and is suitable for proofing. Cold foil stamping is mainly used in narrow web flexographic printing presses, narrow web letterpress printing presses, label coupling machines, rotary printing presses, and waterless offset printing presses. Regarding stamping methods, there are two methods for cold foil: wet lamination and dry lamination.
Wet lamination
The printing process flow is as follows: print the image on the substrate → laminate the cold foil with the substrate with a roller→ dry the UV adhesive on the substrate with a UV lamp to make the image sticky → remove the excess cold foil.
In wet lamination printing, you should pay attention to:
- Water-based and UV ink surfaces can print the adhesive.
- Limitation of printing speed.
- Tension control of the cold foil and substrate.
- It is necessary to install hard press wheels before and behind the UV lamp.
- Can print Fine lines, hollows, and fine dots.
Dry lamination
The printing process is as follows: print the image on the substrate → dry the UV adhesive on the substrate with a UV lamp to make the image sticky → immediately transfer the foil to the adhered image with a press wheel and remove the excess foil.
In dry lamination printing, you should pay attention to:
- The undried, water-based, solvent-based ink surface can’t print with the adhesive.
- The glue must not be too dry or under-dried.
- To be laminated within 12cm behind the UV lamp.
- Laminating foil and substrate must use a high hardness press wheel and high pressure.
- Handling of glue and preservation of the same general UV ink.
Dry lamination printing is suitable for dot, fine line, and other printing. And can do cold foil stamping on a UV surface; the suitable substrate is the paper substrate. After printing must do post-drying treatment, printing should focus on controlling the appropriate printing speed.
Limitations of cold foil stamping
In addition to the limitations of the cold foil stamping process by the adhesive and cold foil, the cold foil stamping process has several limitations that you should be aware of:
- As the foil pattern of cold stamping is floating on the printed surface, its solidity is very poor and must be covered with protection. So in the printed material, the cold stamping must be in the printed surface light or wax overlay to protect the pattern of cold foil, which increases the cost of cold foil and the complexity of the process.
- Due to the poor leveling of the UV adhesive used in cold foil printing, some of the surface after drying is not flat, resulting in insufficient surface brightness of the electrochemical aluminum foil transferred on top of it, and even diffuse reflection will occur. In addition, cold foil printing is currently unsuitable for film materials with shrinkage characteristics (such as PVC, PE, etc.). In these two points, the effect of cold foil stamping is not as good as the traditional hot foil stamping.
- Since the quality of cold foil printing depends on the quality of the adhesive, it is essential to pay attention to the adhesive’s rate and the printing’s suitability and to pay special attention to observation and summary printing experience for better operation in the future.
- Cold foil only can stamp on the smooth surface of the substrate. The adhesive will be absorbed in the rough substrate, resulting in the substrate surface not having enough glue to do cold foil printing. So cold foil stamping for rough surfaces (such as leather, etc.) on the substrate printing still needs to be improved. Therefore, the choice of substrates to pay attention to the smoothness of its surface.
- Cold foil stamping is currently used mainly for printing on rolled substrates.