Litho or offset lithography is a technique whereby an inked image is transferred to the printing material via a plate and a rubber roller. Ink is transferred to the paper via the plate which attracts the inks that are pre-loaded into the machine, and the non-imaged areas attracts a water based film which keeps them print free, leaving the image that was originally transferred to a plate. See video and image below for better example.
The video below makes the whole process a lot easier to understand compared to the explanation and the image. It's crazy how fast it is possible to print; It states in the video that their litho printer can print out 10,000 double sided photo colour quality brochures in less than 3 and a half hours. The video really helps get my head around the whole process, I tend understand things more through doing and seeing things in action, when I read definitions it just confuses me as I try to imagine it all in my head.
Digital
Digital printing does not use an offset method. It prints straight from the printer onto a surface using a digital code. Digital printing refers to methods of printing from a digital based image directly to a variety of media. It usually refers to professional printing where small run jobs from desktop publishing and other digital sources are printed using large format and/or high volume laser or inkjet printers.
Digital printing is charged per sheet (click charge) this is because there is no set up cost involved with digital as opposed to litho, meaning for short runs it works out a lot cheaper but there is a limit for when to change to litho and that is around the 500 mark for full colour, after this point digital isn't cost effective and it makes more sense to use litho.
Digital vs Litho
Digital printing is charged per sheet (click charge) this is because there is no set up cost involved with digital as opposed to litho, meaning for short runs it works out a lot cheaper but there is a limit for when to change to litho and that is around the 500 mark for full colour, after this point digital isn't cost effective and it makes more sense to use litho.
Digital vs Litho
- Digital is faster for short runs because there's little set up time because there's no need to create plates.
- Litho produced prints are generally more tolerant of subsequent over-printing.
- Litho can print much larger sheets from B1 -SRA2 whereas digital can manage a sheet just larger than A3.
- Litho can print a spot colours at a higher level of accuracy although digital presses can pantone colours very well nowadays.
- Litho has a higher print quality although to the average layman they wouldn't notice the difference. The use of graduated tints and large solid blocks of colour would tend to lead to Litho being selected as the preferred process however.