Offset Printing

Offset Printing is where large printing press machines are employed to transfer images onto paper utilising aluminium plates and runner rollers which transfer ink to paper. The image of the page, or design, is etched onto the plates which are then placed on a roller. Using another roller, a layer of ink is fed onto the aluminum plate. This ink layer is then passed to another roller, called the offset roller, which presses the ink onto paper. The most common offset printers use four  colours, each of which are set on a separate plate and roller. 

Plate with Cyan Ink

Plate with Magenta Ink

Plate with Yellow Ink

Plate with Black Ink aka ‘Key’

What is CMYK in Offset Printing?

CMYK stands for Cyan (a light to mid blue), Magenta (a rosy red), Yellow, and Black which are the colours used in the offset printing process. A printing press uses dots of ink from the four colours to make up the image. The CMYK colour model is also known as Process Colour or Four Colour Process.

Why isn’t it CMYB?

The K in CMYK actually stands for Key. Black is called Key because it’s the main colour used to determine the image outcome. Black ink provides depth and shading, whereas the other colours create different colours on the spectrum depending on how they are mixed. For example, cyan and yellow create a green when one is overlaid on the other.

The CMYK colour model

Four colour process offset printing is the most widely used and cost effective colour reproduction system in commercial printing, significantly cheaper than digital printing for large quantity runs!