Several types of print techniques are used in the production of self-adhesive labels. Ellco Etikett covers many of these techniques; digital print, UV Flexo, screenprint and hot foil. In addition, one can also print labels in offset and letterpress.
WHAT IS DIGITAL PRINT?
In simplified terms, digital printing machines are enlargements of office printers. An advantage of digital printing of labels is its fast turnaround of short runs. With a conventional printing press, you would have to obtain and change printing plates, wash the printing units and adjust several additional factors before being able to print the next job. With a digital printer you do not need to worry about much more than a mere change of material. Many customers use the opportunity to print labels with variable data, where every label can be unique. A widely used version of this is serial numbering, but you can merge text and images as well. The campaign “share a Coke” by Coca-Cola is a good example.
At Ellco Etikett we use two different digital printing techniques. The UV inkjet and the digital offset. Common to these is that you usually print in CMYK, also known as “four color print”.
You can read more about digital printing on Wikipedia.
If you want to know more about the digital printers we have here at Ellco Etikett, you can check out this article on Wikipedia about HP Indigo, and this about EFI Jetiron.
WHAT IS UV FLEXO?
Flexography, commonly known as ‘flexo’, is a solution for printing larger volumes. This technique makes high-speed printing possible. The color is transferred to the paper using printing plates (see further down for an explanation). In many ways, flexo can be seen as a new version of the letterpress technology, and it has developed significantly since the beginning of the 1990s. Print quality is now at a level with offset, which has been considered to give the best result in printing.
The corner stone in flexography is the anilox roller. This roller is almost like a swiss cheese – there are a lot of small holes in the surface. By rotating the anilox roller in an ink tray, these small holes are filled with color. A doctor blade removes the excess color from the anilox, before the color is transferred to the cliché and eventually on to the paper. The flexo technique can be used for printing on plastic bags and corrugated cardboard, and of course on self-adhesive labels like we do at Ellco Etikett.
In screen printing, a rubber blade forces the ink through a pattern in a fine mesh cloth, and on to the paper. In earlier days this technique was called silk-screen print because the mesh was made of silk. This is also why it is called serigraphy. ‘Seri’ is the latin word for silk, and ‘graphy’ originates from the Greek word ‘graphein’ – to write or draw. Today the mesh is often made of polyester.
The advantage of screen printing is the color coverage. The color is transferred to the substrate in thick layers and covers very well. That is why screen printing is a preferred method for transparent substrates. You can actually feel the print when you brush your fingers over it. The print is also very color resistant and ideal for outdoor use.
Screen print is often used to make a high-end effect on labels for wine and spirits, with a glossy finish that gives an impression of luxury.
The pattern we want to transfer on to the substrate is called a stencil. The stencil is made in several steps. We start with a clean mesh cloth and coat it with an emulsion. When the emulsion has dried, a film with the stencil pattern is placed on the cloth. Then we expose the plate to harden the emulsion around the stencil. The next step is to wash off the emulsion that has not hardened and end up with the pattern for our print.
Do you want your labels to have a touch of luxury? Well, then we stamp them with foil. Mainly gold or silver, but there is an almost endless choice of metallic colors and variations. For instance, holographic foil is often used for copy protection. The word ‘hot/cold foil’ describes the method where we either heat the foil (hot foil) or use adhesive (cold foil) to stamp it on the substrate.
Foil stamping is used as an addition to ordinary printing, and gives the label décor a much better metallic look than any other technique.
Most label printing presses can be equipped with hot/cold foil units. Ellco Etikett has this equipment on two machines, and both of them are hot foil, which gives the sharpest and cleanest result.
WHAT IS EMBOSSING?
Well, embossing is when you create a raised relief pattern in the substrate. This is often made by pressing the substrate between two plates where one of the plates have a protruding pattern (the male) and the other has a corresponding pattern inwards (the female). Then you get a protruding pattern in the substrate. As you probably already have guessed – debossing gives the opposite effect. You simply switch the plates places and get an inwards pattern. Some labels have both embossing and debossing.
Normally we combine embossing with a shiny ink, finish or a metallic foil to highlight the effect. But it can also be done as a standalone effect, called blind embossing/debossing.
Check out this article on Wikipedia for further explanations.
LETTERPRESS (a yesteryear star in the history of Ellco Etikett)
In the early days of Ellco Etikett most of our machines were based on the letterpress technology. Printing plates made from polymers are used for printing, where raised areas transfer the ink to the material. This is similar to flexo, but the clichés are hard and the color used is very viscous in letterpress.
Depending on the machine used the clichés are attached to a plate or a roller and this is pressed against the substrate with the preferred pressure. You have to use one cliché for each and every color of the label.
You can read more about the letterpress technique on Wikipedia.
What is a cliché?
According to the dictionary a cliché is a plate with which you can print illustrations and text. In short, the plates are like stamps where the illustration or text to be printed is raised above the plate. In the printing machines the elevated area is coated with ink and transferred to the substrate as an imprint.
In flexo and letterpress the printing plates are made of photopolymer, which is a material that hardens when exposed to light.
There are multiple steps in making a cliché of photopolymer. First you cover the raw photopolymer plate, with a thin film, and expose the surface to light. Think of the film as a negative from an old-fashioned camera. It is only the imprint pattern that is exposed to the light and hardened. Then you wash of the residue – the non-hardened photopolymer, and after a quick dry and additional hardening, you have your pattern ready printing. Today most printing plates are made digitally but you still need to wash and harden them.