Offset printing is one of the most common printing techniques. An inked image is transferred from the printing plate to a rubber blanket on a roll, then further onto the printing surface.
The whole process is a complex interaction between the ink, fountain solution, blanket, paperboard characteristics, and drying mechanisms, together with the pressure, temperature, and press speed.
The main advantages of offset printing are consistent image quality, quick production of printing plates, and the opportunity of making continuous refinements ensuring a more precise result. This makes offset printing particularly suitable for large volumes of high-quality print applications such as newspapers, magazines, brochures, and books.
There are two main types of offset printing, web offset and sheet-fed offset. Web offset printing allows simultaneous printing of both sides of the paper, whereas sheet-fed offset presses print one side of the paper at a time. However, often these presses contain a perfector cylinder which enables printing on both sides in one pass.
Web offset printing allows simultaneous printing of both sides of the paper, whereas sheet-fed offset presses print one side of the paper at a time. However, often these presses contain a perfector cylinder which enables printing on both sides in one pass.
Cold-set web offset
Publications with shorter life span and lower quality requirements, such as newspapers, are usually printed using a cold-set web offset printing method. The ink is absorbed into the underlying paper, which means that a newly printed newspaper is not completely dry. This causes the ink to smudge and is the reason why you sometimes will find stains on your fingers after reading the morning paper.
Heat-set web offset
Heat-set web offset printing is suitable for publications with higher demands on quality, such as magazines, catalogues, and direct marketing. The paper is transferred through an oven which dries the ink and makes sure that no smudge occurs.
Offset printing in sheets, with no need for oven drying.