What is Spot Colour?
In offset printing, a spot color is any color generated by an ink (pure or mixed) that is printed using a single run. The process of offset printing in full color consist of Cyan, Magenta, Yellow and Black (CMYK).
The process of offset printing in full color consist of Cyan, Magenta, Yellow and Black (CMYK). When the need to match a particular color (a background or specific color in a logo or company color) on a printed piece, the use of a spot color is utilized. The main reason that the spot color is utilized is to maintain the color fidelity or accuracy of the color throughout the print run.
Normally any or mostly any color can be created from the CMYK color model, but when large areas are being printed with the specific need of a special color, the control envelope on the printing process is limited, and sometimes a compromise on color is required. An example is an image that has a blue sky (Cyan and a hint of Magenta), and green grass (Cyan and Yellow) has the requirement of any of the base colors being used (Cyan, Magenta and Yellow in this case) for the special color – say Purple (almost equal amounts of Cyan and Magenta) , then the amount of the contributing color to the special color will be limited to either be the correct amount for the green grass, the blue sky or the Purple special color, all three demanding different degrees of Cyan.
The printer needs to have a special file created for the spot color in addition to the CMYK colors. This spot color will eventually be a plate that utilizes an extra printing unit on the press to print the color to the printed sheet.