OFFSET, DIGITAL AND
SERIGRAPHY PRINTING
Offset, digital and serigraphy printing
Offset
The system focuses on the repulsive action between water and various fatty substances. The offset technique is also called indirect because the sheet is not in direct contact with the aluminum sheet, but three cylinders are used and contact with each other which, in order, have the task of: carrying the sheet; receive the image of the plate and put it on the sheet of paper; supply the appropriate pressure according to the thicknes of the substrate to be printed.
Before reaching the cylinders, the ink passes through the grinding group: it is a series of rollers of different diameters which have the purpose of making the ink more fluid and eliminating any lumps.
The second of the three cylinders (positioned centrally between the other two) is made of rubber, a material that allow you to print flawlessly even on surfaces that are not perfectly smooth. The lithographic plate therefore carries the ink to the rubber cylinder which in turn transports it to the support thanks to the pressure cylinder. After these steps, the printed product will come out, which will only need to be dried.
In the case of plastic card printing, at this stage the product is not yet die cut as we know it buti t comes in sheet of various sizes which will then be die cut.
Following this process, if on the one hand the print guarantees excellent colore rendering and the brightness and intesity of the colors are always optimal, on the other it does not have the elasticity to be able to add variable data at the same time.
Furthermore, given that printing takes place on larger sheets, there will always be a tolerance with respect to the number of cards needed.
Digital
Much simpler, in some ways, is the digital printing system. In this case there is no need for any printing system: the processi s generated by electronic processes and the printing is direct, as the impression occurs directlly on the substrate to be printed. This is why digital printing has very low start-up costs, but on the other hand higher operating costs compared to offset printing. Therefore, it is usually used – for obvious reasons of convenience – for medium-low runs.
By virtue of an ever higher print quality and the almost absence of production costs, recent research shows that digital printing can be convenient even for print runs that were once the absolute preserve of offset.
Digital printing also has the advantage of being much faster at the process level than offset, which requires preliminary settings for printing and longer times for drying the ink.
Serigraphy
Serigraphy printing or screen printing is a permeographic printing technique that today uses a polyester fabric as a matrix, stretched on a wooden or metal or plastic frame called “silk screen framework” or “silk screen frame". The fabric used i salso called “serigraphy printing fabric” or “screen printing fabric”.
The term “serigraphy” derives form the Latin “sericum” (“silk”) and from the grego “γράφειν” (gràphein”, “to write”). The first fabrics that served as a screen printing support were silk.
Serigraphy printing compared to other printing technologies allows you to check and choose the thickness of the ink deposited. It is important in this regard to point out that the theckness of the ink is one of the fundamental parameters, naturally combined with the nature of the pigments and binders selected for its composition, which determine the external resistance and resistance to light and mechanical abrasion of a decoration.
Today the screen printing technique is possible on every substrate and is required to give safe and intense shades of color or for printing inks with particular characteristics. Only in silk-screen printing can the wide range of special effect be obtained, determined by the availability of ranges of specific inks which include glossy, matt, satin inks, with relief effects, glitter, metallized, iridescent, luminescent, thermochromic, photochromic, retro-reflective, soft-touch and others, which greatly embellish the printout.
Another feature that derives from the use of the high thickness of the serigraphy printing ink is the possibility of creating a print with a marked and high color rendering as well as lasting over time. The high color rendering is used when the visual impact is really important, such as in promotional launches of products destined to stay outside for long times.