Spot color

[1] The widespread offset-printing process is composed of the four spot colors cyan, magenta, yellow, and key (black) commonly referred to as CMYK.

The dot gain, hence the screen angle and line frequency, of a spot color vary according to its intended purpose.

Spot lamination and UV coatings are sometimes referred to as 'spot colors', as they share the characteristics of requiring a separate lithographic film and print run.

However, because of the complicated process, spot colors are effective at preventing forgeries of money, passports, bonds and other important documents.

Money printing for example, uses secret formulae of spot colors, some of which can be seen by the naked eye and some that can only be seen by using special lights or applying certain chemicals.