Editor’s Note: This content is sponsored by Xeikon

Today’s labels are more than just pretty pictures. Digital production of labels requires many components, such as the printing press, toners/inks, varnishes, suitable substrates, appropriate software solutions as well as the right finishing equipment. The best label and packaging solutions include all these components in a well thought-out fashion.

Self-adhesive or pressure-sensitive labels are transformed into final products only when finishing has been applied. It allows the product to remain visible despite the presence of foil or varnish and makes it easier for the blind or visually impaired to read using Braille characters. The following table provides an effective overview of the use of labels in various sectors and indicates the type of print finishing normally required for a specific sector. While these details are based on surveys of conventional printing technologies, they apply to digital printing as well, with just a few exceptions.

Varnishing

Here, mainly UV liquid varnishes are used for both for protecting the product and for aesthetic reasons. Anytime varnish is applied in the digital printing process – regardless of whether the system uses dry or liquid toner/inks – the primary function of the varnish is to provide adequate protection from wear and scratching. In inkjet printing, varnish is mainly used to enhance appearance, and to provide the printed product with a shiny finish of a uniform brightness. Pharmaceutical labels are normally finished with spot coatings and water-based varnishes. This means it is possible to add over-printing to the label later in the packaging production process.

Laminating

If a label is likely to be exposed to more demanding conditions of use, laminates are preferred in the print finishing process. Laminates provide protection from mechanical abrasion, chemical solvents and oils and also include functional barriers, such as sunlight protection factors. In these cases, a self-adhesive laminate or a foil pre-treated with UV adhesive can be applied directly to the label. Laminating offers a long shelf life.

Punchers

Rotating punching dies are the norm. Flatbed solutions are used in individual cases, although these tend to be rare. Conversely, with most punching technologies (e.g. collapsible boxes, IML and wet-glue labels), the material is not cut through fully, with only the top layer being scored or cut (= face stock). Since the advent of digital printing with small print runs and rapid production cycles, punching technology has been revolutionized.

The manufacturing of fully rotating punching dies takes some time (unless they are already available in store). This explains the existence of semi-rotating punching dies. These solutions do not, of course, reach the speed of fully-rotating dies. However, their shorter setup times and the lower costs are very attractive to label converters. Tool forms are also easier to set up as there is no need to replace the magnetic cylinder, and this means that the service provider can usually deliver within 24 hours.

This format is suitable for the digital printing business model. As in the past, flatbed punchers have been used for specific applications. For instance, they are commonly used for wine labels and frequently combined with a foil system. The setup times and costs for flatbed solutions remain within reasonable limits.

Laser punching

The biggest advantage with the use of digital laser stamping or laser cutting systems is that digital printing and secondary processing can now be completely integrated as part of the workflow. This allows label converters to draw the greatest benefit from the changing motifs and formats, in both printing and secondary processing procedures. The disadvantage is that metallised materials, PE and vinyl do not lend themselves to optimal cutting, because the laser cutting solutions burn away the material. Nevertheless, this is overshadowed by the advantages, especially in standardized production procedures with rapid reaction times and a large number of varying cutting contours. 

Braille lettering

Under European law, prescription medicines and their dosing regimens must be identified with Braille lettering. Pharmaceutical labels without this type of lettering are not permitted. The Braille lettering can either be produced in the silkscreen or the stamping process. However, stamping can cause tears in the material whichs make it more difficult to mount the label. There are digital printing solutions that make it possible to apply Braille markings with a special ink, which is, in fact, a kind of adhesive that spreads to the correct size for a Braille dot.

Embossing

The visual experience of a printed product can often be confused with a raised varnish, as the paper is deformed by the stamping process. The aesthetically pleasing textured effects are achieved with relief or etched printing plates. Of course, this means figuring in additional setup times and costs. Because of the added complexity, stamped labels are frequently used for wines and spirits. Stamping effects can be produced quite simply and with good results on digitally printed materials.

Stamping foils

In the cold-file transfer process, UV adhesives are pressed onto the label and provide the backing for the subsequent metallized surface layer - adding the gold, silver and metallic color effect to the label. In the hot-foil stamping process, special printing plates are used to stamp the metallic design onto the substrate with the application of heat and pressure. The cold-foil transfer process is mainly used for cosmetics product and drinks labels, as the results it produces with synthetic, water resistant and non-absorbent materials are outstanding. Conversely, hot foils cover the widest range of materials, such as thick wine labels, because adhesives are not used or the adhesive is already in place on the hot-transfer foil.

Stamping foils in digital printing

There are many possible variants when it comes to digitally printing labels: metallic effects on cold foils, a repeating pattern that can be applied prior to digital printing in large print runs, and markings and lettering that can be printed digitally at a later time. This is particularly practical where there is no need for primers or preliminary treatments in the digital printing process. The use of cold foils after digital printing is less common, unless in connection with extremely high print runs. Factors to be considered here are setup time, harmonization and a higher rejection rate. This represents an extremely cost-efficient type of print finishing with progressive motifs and is perfectly suited to both dry toner and inkjet printing systems.

Hot foils are more robust and involve fewer variables when it comes to achieving good results. For this reason this process is an ideal method for finishing digitally printed labels. With reference to inkjet printing, it is important that during secondary processing post-printing surface tension is taken into account. The risk is that the file transfer does not adhere perfectly to the inkjet inks.

Raised printing

It is possible to achieve visual effects similar to those in embossed printing with the application of a thicker layer of varnish. This effect can be achieved practically only through silkscreen printing. Of course this finishing procedure is eminently suitable for digitally printed labels.

Cutting/winding

In the sphere of digital printing, the starting point is a fairly large reel which is cut up into individual label batches for winding. It is in this form that they reach the packaging line for application. To maintain the performance of the printing press, cutting and winding must be done rapidly. Depending on the size of the label and the width of the reel, cutting can cover between two and ten webs. This has a substantial effect on setup time, because up to two cutter blades must be adjusted for each web. When very large production runs are needed, it’s smart to have this phase handled by a separate winding system. 

Discussion: Inline vs. Offline

The decision to go for inline or offline finishing is primarily dependent on the business model and the specific priorities of the company in question. It is useful to carry out some finishing operations inline with the digital printing press in order to save time and costs, and to keep the rejection rate low, while maintaining the speed of throughput. Inline finishing requires the full concentration of the machine operator as more time is required for setting up. Not every company is prepared to employ one or two additional machine operators to provide backup. If the sole operator is absent, the loss of time is immense. 

To arrive at the ideal solution, there are a number of factors to consider:

Factor 1: Will the printing company be producing all kinds of labels (wine, food, pharmaceuticals, cosmetics) or concentrating on a single sector? The former calls for versatility. It is better not to have too many processing steps undertaken inline to permit more flexibility in reaction. In the second case, inline solutions are the better option.

Factor 2: Is the company‘s main focus on rapid reaction times or is digital printing seen as a complementary activity in conjunction with conventional printing? In the first case, as few processing steps as possible should be involved. Here, inline solutions are advantageous. In the second case, consideration should be given to separating out work stages: digital printing in the printing department and cutting and winding in the secondary procession or finishing section.

Issue 3: In case of just-in-time large-scale orders that only require limited punching operations, inline production is recommended.

Issue 4: What is the recommended solution for small companies? Smaller operations with a more closely-involved workforce benefit from inline solutions.

This is only a sampling of the issues to be addressed when trying to identify the appropriate solution. At the same time, it is critical to involve employees in the decision-making process with regards to new technology. The proportion of inline finishing solutions today represents between 15 and 20 percent of the total. However, it is only a matter of time until the market reacts and adapts to new finishing solutions.