Cold foil finishing
Cold foil transfer is a printing method in which a film is adhered to a printing substrate in order to obtain a refining effect. In contrast to hot foil stamping , no high temperature, additional tools and, above all, no complex offline process with hot foil stamping machines (in the high-pressure process ) are necessary. In addition, with cold foil stamping , the applied film can usually be printed “inline”, i.e. directly after application in the machine, which enables a large number of different effects to be achieved.
How the procedure works
In addition to the application of the film via an offline cold foil transfer system, there is the relatively new and significantly more efficient inline process . A total of two printing units are required for applying the film. In the first printing unit, a special, pasty adhesive is applied to the printing substrate according to the motif using the inking roller system and a conventional offset plate. The fineness of detail corresponds to that of the offset plate. In the second printing unit, the film is transferred via a winding and unwinding unit. To do this, the film is passed between the rubber blanket and the impression cylinder. The pressure of the rubber blanket transfers the film to the areas that were previously provided with adhesive. The portion of the film that is not glued is then rolled up again with the carrier layer in the roll-up station. The substrate can be printed with the foil applications in the following printing units. Of course, the first two printing units can be used again for conventional offset printing with minimal set-up time after the film has been applied.
advantages
Refinement with cold foil differs from other processes in one particular respect. Due to the possibility of overprinting cold foil with conventional, UV or hybrid printing inks, new, metallic colors can be created. With a silver foil alone, a wide variety of other colors can be generated - for example, a warm gold tone is created when the foil is overprinted with yellow and magenta components. In this respect, the cold foil transfer can be viewed as an “extension” of the color space. Among other things, this makes it possible to produce colored samples with just one film. With modern inline processes in particular, overprinting takes place in one pass with the cold foil transfer. Register accuracy and resolution are extremely high, while setup times are very short. In addition, the films can be applied at full production speed.
Possible problems
Compared to hot foil stamping, the effect of cold foil is more matt, not quite as shiny and more sensitive to scratches. Papers with an open surface structure (natural papers) cannot be finished with cold foil.
Appropriate application
The properties of cold foil transfer make it suitable for a whole range of printed products. This ranges from packaging to commercial jobs and facsimiles. Due to the high resolution, many design variants can be implemented, from the font to filigree design elements.
Suitable motifs
Colored, metallic motifs are particularly suitable for cold foil transfer. In addition to surface finishing, the process is also suitable for filigree motifs, since registration problems are avoided thanks to low temperatures. With cold foil transfer, the results are precise, both for thin lines and for solid areas.
The components to be refined should stand out as sharply as possible from the background. Highlights can be left out of the cold foil. On the other hand, very soft and larger light surfaces are less suitable.
Overprinting of foil areas
By overprinting a silver foil, a large number of color nuances can be achieved, including silver or gold effects. Overprinting with orange provides e.g. B. a golden metallic effect, with blue a blue metallic tone, with black a deep, high-gloss black. So you are not tied to a specific type of film, such as B. in hot foil stamping. The desired color is produced on a standard silver foil. This makes the process more flexible and saves costs. Image or line elements can be displayed on the slide. Care should be taken that fine line elements on the film lose contrast due to the high gloss. This means that thin lines are no longer perceptible from a certain viewing angle, fine writing with a low area coverage becomes difficult to read. To create a clearly perceptible contrast, the following guide values can be used:
Lines
- ≤ 0.5 pt min. 50 percent area coverage
- > 0.5 pt min. 30 percent area coverage
The lighter the color, the worse the contrast on the film. In order to achieve legibility and contrast, especially with light colors such as B. yellow, orange and pink thicker line widths and high area coverages can be selected.
Overprint the screened film
Another effect can be achieved if the film is screened and then overprinted. A grid gradient in the film influences the color effect on the one hand and the gloss on the other. The color tone appears purer than on a full-surface silver foil, gradations in the color tones are more clearly perceptible. The smoothness is suppressed somewhat by the grid structure, the metallic effect and the high gloss decrease slightly. In the case of a grid pattern of the film, it must be ensured that the film elements do not have an area coverage of 40 percent.
Overprint fine line elements
The inline process ensures high register accuracy even when overprinting fine film elements. The register corresponds to that of offset printing, so very sharp transitions between foil areas and the other printed image are possible. The same applies to overfilling the film as with color printing.
Security features
Foil elements serve as proven security features for various products such as folding boxes and admission tickets. The use of foils in securities printing would also be conceivable. Product counterfeiting can be counteracted by using an effect film or film combinations. The ROLAND InlineFoiler Prindor enables the combination of flat as well as fine line and raster elements as well as the option of overprinting. A wide variety of security features can be created in this way.
Create a document
The film is treated as a "fifth color" and is therefore created as a special color. If the film is to be overprinted, the film areas must be set to overprint and placed in the foreground in most programs. The settings can be checked with the Adobe Acrobat function »Simulate overprinting«. As with a customary special color application, this is done using the color separations.
Application as a full surface, in a grid or as line and writing elements
Full surface
A full surface of any size can be neatly realized, large-area film applications are possible without any problems. Overprinted foil areas or recessed fine elements attract the viewer's attention.
Grid
When using a coarse grid of 30 l / cm to 60 l / cm, grid fields with foil can be "printed" in a very good quality. Area coverages of 40 to 100 percent show that the film is easy to remove. This creates interesting effects that are only possible to a very limited extent with other methods.
font
Very fine writing elements can be implemented both positively and negatively.
- Serif font: from 5 pt
- Sans serif font: from 3 pt
The writing is easy to read and has a high edge definition.
Line elements
Fine lines from 0.25 pt are displayed cleanly with excellent edge definition.
Service providers with special services
Compact Foilers CF1000 - cold foil finishing and holographic effects
The CF1000 module allows refinement with cold foil as well as relief foil / cast and cure to achieve holographic effects. Since the module is mobile and not directly connected to the printing machine, it can be used at different points on the printing machine as well as on different printing machines using docking stations. The non-contact running of the film prevents contamination of the printed matter. Thanks to the extremely precise rewinding of the film and a sophisticated register system, the expensive films can be used multiple times. The rolls can be loaded at ground level without lifting tools. Parallel tracks and full machine speed allow many possibilities.
FoilStar - Heidelberger Druckmaschinen AG
Heidelberger Druckmaschinen AG (Heidelberg) has developed its FoilStar module for the Speedmaster CD 74, CD 102 and XL 105 series. With the FoilStar, cold foil is applied using the offset printing process, which enables metallic refinements to be applied to a wide variety of substrates. The grammages range from 70 g / m² to 400 g / m². The film can also be applied in a multi-web system - up to six webs with different films in different web widths can be used.
ROLAND InlineFoiler - manroland sheetfed GmbH
Examples of use for the ROLAND InlineFoiler Prindor are gold and silver effects; almost any variant can be realized using special pattern designs. The metal foil transferred to the substrate can be overprinted directly. This means that almost any color shade can be reproduced and there is no need to be bound to certain types of film.
UV Inline Casting and Foiling - RYOBI Limited
With the UV inline casting and foiling module from RYOBI, inline effect finishing (UV casting) can be carried out instead of cold foil finishing. The technology is based on the application of a UV varnish, which is surface-refined with the help of a relief film and UV-hardened. The UV adhesive for cold foil finishing or UV varnish for effect finishing is applied via a coating unit instead of a printing unit.
Potential of the finishing process
Cold foil transfer is a relatively new finishing technique. In particular, research and development of the material components “types of film, printing material, film adhesive and printing inks” have not yet been completed. As part of the research and development project PrintPerfection , the service providers Margreff Druck und Medien and GG-Media are available with tests and material developments. A proof system for simulating the cold foil for presentation purposes is now also available.
Individual evidence
- ↑ cf. Service description of the Reproductions - Society for scanner lithography and electronic image processing mbH ( Memento of the original dated November 15, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
Web links
- About cold foil finishing in the finishing lexicon