Several types of print techniques are used in the production of self-adhesive labels. Ellco Etikett has a machinery which covers many of these techniques; digital print, UV Flexo, screenprint and hot foil. There are two more techniques used to make labels; offset and letterpress.
WHAT IS DIGITAL PRINT?
In simplified terms, digital printing machines are enlargements of office printers. The advantage of digital printing in the field of label manufacturing is in fast printing of short runs/volumes. Where one needs to obtain and change printing plates, wash the printing units and adjust several additional factors before being able to print the next job when working with a conventional print technology, with a digital printer one doesn’t need to worry about much more than only a mere change of material. Many customers use the opportunity to press with variable data. Then 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 press with CMYK, also known as “four colour print”.
You can read more about digital printing on Wikipedia.
If you want to know more about the digital printers we use 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’ or ‘UV Flexo’, is a solution for printing larger volumes. This technique makes high-speed printing possible. The colour is transferred to the paper using a cliché/printing plates(see further down for an explanation). Flexo can be, in a more simplified sense, understood as a new version of letterpress – the technique has developed significantly since the beginning of the 90s. Print quality is now considered to be as good as offset, which has been considered to print the best result.
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 the color bed, these small holes are filled with colour. A blade removes the excess colour from the anilox, before the colour 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.
Screen printing is colour being pushed through a pattern in a fine mesh cloth, by a rubber blade, and transferred on to 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 made of polyester.
The advantage of screen printing is the colour coverage. The colour 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 colour resistant and ideal for outdoor use.
Screen print is often used to make a high end effect on labels for wine and spirits, with high gloss and 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. A film with the stencil pattern is placed on the cloth, when the emulsion has dried. Then we use a light to harden the emulsion around the stencil. The next step is to clean of the emulsion that has not hardened and end up with the pattern for where the colour shall be pushed through to the substrate.
Do you want your labels to have a touch of luxury? Well, then we imprint them with foil. Mainly gold or silver, but there is almost an endless choice of metallic colours and variations. For instance, holographic foil is often used for copy protection. The word ‘hot/cold foil’ describes the method – the foil is leaf thin and attached to a liner – we either heat the foil (hot foil) or use glue (cold foil) to imprint it on the substrate.
The foil imprint is used as an addition to ordinary colour print, but it provides the labels with a better result if you want the metallic look of the label décor.
Most of the machines that print with the basic printing methods can be equipped with hot/cold foil works. Ellco Etikett has this equipment on three machines, and all of them are hot foil works, which gives the sharpest and cleanest result.
WHAT IS EMBOSSING?
Well, it 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 allready have guessed – debossing gives the oposite 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 without this effect – then it is 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 technique ‘letterpress’. Printing plates/cliché made from polymers are used for printing, whereby their raised areas transfer the ink to the material. Almost like the UV Flexo, the difference is that the clichés are hard and the colour 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 colour 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 pistons where the illustration or text to be printed are raised above the plate. In the printing machines the elevated area is coated with paint and transferred to the substrate as an imprint.
In the UV Flexo and letterpress the clichés 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 material, 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 for imprint. Today we have of course digital solutions to the making, but it still needs to be washed and hardened.