Offset printing was first applied back in 1903 by Ira Washington Rubel. Followed by brothers Charles Harris and Albert Harris who built an offset printer for the Harris printing company. These are the two fundamentals that make the strong development of this printing technology.
After many ups and downs, in 1950 offset printing became the most popular printing technique for the commercial printing industry. Besides, after many improvements have been made to the letterhead, ink and paper, optimizing the printing speed and the lifetime of the letterpress layout. Today, this printing method is used in most industries.
1. The concept of offset printing in packaging production
Offset printing is a printing technique in which ink-stick images are pressed onto rubber sheets (also called offset sheets) and then pressed onto paper surface. When used with lithography, this technique prevents water from sticking to the paper with the ink.
This printing method has many advantages so it is very popular with manufacturers. In particular, the outstanding advantages include:
- The image quality is higher, sharper and cleaner because the rubber pad is evenly applied to the surface.
- It is applicable on many surfaces, even on non-flat surfaces (such as wood, fabric, rough leather).
- Printing sheets are easy to make.
- Printouts last longer.
Read more: Inspiration From Offset Printing Products
2. Steps of offset printing packaging
2.1 Design and Prepress
The information should be presented on the design both in content, form and color according to the actual needs of the business or the customer. When all is done, the process move to the next step, called outfilm.
2.2 Output film
After the design is completed, the printing technician will publish it to outfilm. For print versions with photo, the film will be out in four panels representing four layers of color: C (Cyan), M (Magenta), Y (Yellow), K (Black).
CMYK color system is the basic color system that can mix to create all the other colors. The necessary colors are a combination of 3 or 4 colors with many different parameters to achieve many different color results. This process is called “four film output”.
2.3 Exposure the zinc plate
After having 4 films, the printing technician will expose each sheet to the zinc plate. To put it simply, to take a picture of each film on each plate with a zinc exposure machine. This is the third step in offset printing.
2.4 Offset printing
During offset printing, the technician will print each color one by one, the arrangement of the order of each color will depend on the technician’s experience.
Firstly, the printing technician will choose one of the 4 color zincs to install on the offset printer’s batch. In the ink tray, the technician will also insert the silimar ink. For example, C-colored zinc (Cyan), the technician also prints ink C and proceeds to print. The batch that goes back to the paper will smash the print element onto the print media.
When it’s all done, the technician will remove the zinc, clean the old ink, install new zinc, print the new colored paper and continue the same process.
The process proceeds sequentially until all 4 colors, the 4 colors that are printed on top of each other, produce the final print.
During the printing process, the technician will have to test the drafts to ensure the color is stable. In printing processing, the printer must deduct paper wastage to ensure quality.
2.5 Post-print process
The final step to complete the offset printing is the post-printing processing. Typically, the most widely used post-printing processing process is lamination and glossy lamination. In particular, matte lamination will create smooth and soft surface. Glassy lamination will make the surface of the ball completely up.
Matte lamination is a process of embellishing the product by applying a thin film layer on the surface of the leaflet after printing. This will help the printing look smooth and help the image become eye-catching.
To ensure that the offset printing process does not occur errors, the printing technician must be really meticulous in every step, to create quality prints.
Khang Thanh – The packaging manufacturer in Vietnam specializes in producing paper bags, boxes, POSM and so on. Contact us to support your brand with the right packaging:
KHANG THANH CO., LTD – HOUSE OF PACKAGING
Tel: (+84) 77 8878 222