Offset printing is an indirect printing system that derives from lithography in which the plate is partially wetted with water that repels grease ink. It was invented by the American printer Ira Rubel around 1900 when he worked with a lithographic machine and he observed that if instead of printing directly he printed on rubber, the impression was sharper.
For printing, four color inks are used, the famous CMYK: Cyan, Magenta, yellow and black. All design information, images, color backgrounds, etc. It breaks down into percentages of those colors. With this information we will record the aluminum plates, with a laser we draw on the plate what we want to print, we will need a plate for each ink. For more info visit https://www.kiasuprint.com/common-company-seals-singapore/
The offset printing machines are divided into “printing bodies”, each printing body is able to print only one of the CMYK colors, all the printing bodies are equal to each other, depending on the ink that we put on it, and it will print from a color or another. The iron is placed rolled on the plate cylinder, first the wet rollers apply water with additive, in the areas where there is no drawing there are small drops of water in some microscopic pores that the iron has, the areas where there is a pore pattern It is closed by the heat of the laser and stays dry.
Next, the ink rollers apply the ink. Since the ink is greasy, the areas where there are drops of water repel it and the ink “takes refuge” in the areas that are not wet, that is, in the drawing. We already have the plate inked with the image we want to transfer.
A perfect impression
At https://www.kiasuprint.com/businesscards-namecards-printing/products/ one could transfer directly to the paper, but that would cause a very fast wear of the plate and an imperfect impression. What we do is use a rubber roller that we press on the iron, in such a way that the ink that was in the iron remains on the roller. This rubber roller is the one that we press against the paper to transfer the ink and serves as a shock absorber and controls the pressure, which compensates for the inequalities of the paper and the ink reaches the bottom of any depression or grain. Also visit https://www.mandreel.com
Advantages and disadvantages of offset printing
Among the main advantages of offset printing we can mention:
- Large runs of economic cost can be printed.
- For large runs it is faster than digital.
- It provides an excellent photographic quality.
- You can use all kinds of papers: stucco, verjurados, with textures …
- It supports the use of special inks, pantones, gold, silver, varnishes.
- Sizes of paper larger than in digital printing.
Some of the disadvantages of offset printing are:
- The putting in machine is complicated and expensive.
- Inks can cause repainting if they are not allowed to dry sufficiently.
- You cannot manipulate the work until after 24 hours.
- There may be color instabilities during the run.
- All printed copies must be the same. Cannot be customized