Offset Printing

Offset printing is a common printing technology that is widely used for various applications. The technology has an advantage in printing very high-quality labels. The offset technology can reproduce very small elements and fine lines that require great accuracy.

Offset printing in Rotoprint

Rotoprint has several offset printing presses that are specially configured to provide the optimal combination of the advantages of offset printing and many embellishment possibilities. 

Our offset presses provide high quality printing, with stable and predictable parameters and are efficient for both small and very long runs. The flexibility of the machines allows us to efficiently print jobs with various numbers of colors, change the order of some colors and effects, and consistently repeat the process so that your products always look their great on the shelf. 

Our team has extensive experience in offset printing, which allows us to quickly respond to new and non-standard orders, as well as recommend the best approach to achieving the results you require for your products.

Offset printing applications

Offset printing has established itself as a widespread technology, on the one hand, because it allows the achievement of very high quality, and on the other hand, it is a technology that has proven itself over time. 

Although offset printing is primarily used when printing on paper media, offset printing is also used on other synthetic materials and films for certain applications. 

The make-ready of the printing press is relatively cheap and fast and enables offset printing to be effective in medium and long runs, and in Rotoprint, thanks to the high level of automation of the process, it can also be effective in short runs.

Technology description

Offset printing is a method of transferring the ink onto the printed material with a combination of:

• thin aluminum plates, with a special coating

• center offset cylinder with rubber-like offset blanket

• a combination of multiple small cylinders divided into groups

• water

• ink

A common misconception is that the offset plate is embossed and accordingly transfers the ink by applying it to the convex parts. This is called letterpress printing, but offset printing is not working like that. It belongs to the group of lithography, which is based on the principle of accepting (hydrophilicity) or rejecting (hydrophobicity) of water. 

The thin aluminum plate we mentioned is treated with a layer that does not retain water (hydrophobic). It is applied to aluminum grain, which retains water (hydrophilic). 

By a special method, usually using a thermal laser, that part of this coating where we don't want to have an image is removed and the aluminum underneath the coating is exposed. 

The plate is then mounted on a cylinder and, by rotation, passes successively first through shafts which apply water and then through shafts which apply ink. The water covers the areas with exposed aluminum, then the ink is absorbed only by the coating, as the water repels it. This leaves ink only where we need it. 

Then the ink, which is applied only in the required places, is transferred to the offset rubber blanket. The offset blanket finally transfers the image onto the media. Although the technology seems complex and with many stages and processes, it has several advantages:

• the coating of the aluminum plate is extremely sensitive and can form very small and precise dots

• the offset blanket allows the metal of the plate to not be in direct contact with the material we are printing on, which improves ink transfer on the final product