Offset Litho Printing

What Is Litho Printing?

In a nutshell litho printing uses wet ink and printing plates whilst digital printing uses toners on a press similar to a giant office printer! Digital printing is more suitable for shorter runs and litho printing for longer runs.The inked image is transferred from a printing plate to a rubber blanket and then the image is transferred again to the paper. Generally the printing will be done out of the standard four-colour process. This means that the artwork is separated onto four different printing plates and each plate prints a specific single colour – cyan, magenta, yellow and black (CMYK). Together these colours combine to create a full-colour print.

Occasionally additional printing plates might also be added to print spot colours. These may be special inks such as fluorescent or metallic or a specific Pantone ink that matches a corporate colour. Similarly, there might be times when fewer colours used such as two-colour printing where only two specified colours will be printed, and because only two printing plates are being made this is cheaper than four-colour litho.

Some points about litho printing to bear in mind

  • There’s a significant cost attributed to ‘making ready’ the job – the cost and time involved in making the plates and in running the ‘spare’ material that is required until all the plate images are in register and the job can be run. However, once this is done the cost per copy will be cheaper than digital printing on longer printing runs
  • Because the setup costs are large, we batch together lots of print jobs on the same plates when they’re on the same stock – this allows us to spread the costs between jobs!
  • Printing is not limited to CMYK – we can add special or spot inks can be to enhance prints.
  • Because physical plates are made for litho print, every impression is the same, this is why we can’t “spit a run” between multiple image or do variable-data this way – we can do it digitally though!
  • The turnaround time is longer with litho, usually a 3-4 working day average. This is because time has to be allowed for the ink to completely dry before finishing and longer run jobs have to be scheduled to run on our bigger litho presses.