Spot colour and its uses
In litho or offset printing, a spot colour is any color generated by an specified ink that is printed using a single print run.
In the full colour printing process the basic printing colours are CMYK. Those four colours will print to offer virtually every colour you can see, but not all. The CMYK process is not perfect, it is flawed. It cannot reproduce all the colours from your computer screen – some of these colours may fall outside the ‘gamut range’. Certain other colour are difficult to reproduce.
If you specify a Pantone colour in your design it will offer a CMYK breakdown. You would notice from the swatch that the Spot colour is different from the CMYK. This is the flaw.
If your this is critical, it is a brand colour perhaps, you could specify a Spot colour in the printing process. An addition fifth plate is added during the printing process which when printed is exactly the same of the Spot colour on the Pantone swatch.
You are not limited to one, it is possible to add a sixth, or seventh.
When making a multi-color print with a spot color process, every spot color needs its own lithographic film. All the areas of the same spot color are printed using the same film, hence, using the same lithographic plate. 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
Spot lamination and UV coatings are also referred to as ‘spot colors’, as they share the characteristics of requiring a separate lithographic film and print run.
The widespread offset-printing process is composed of four spot colors: Cyan, Magenta, Yellow, and Key (black) commonly referred to as CMYK. More advanced processes involve the use of six spot colors (hexachromatic process), which add Orange and Green to the process (termed CMYKOG). The two additional spot colors are added to compensate for the ineffective reproduction of faint tints using CMYK colors only. However, offset technicians around the world use the term spot color to mean any color generated by a non-standard offset ink; such as metallic, fluorescent, spot varnish, or custom hand-mixed inks.
- Pantone, has been dominant spot color printing system since time began.
- Toyo and DIC are common spot color system in Japan.
- RAL (color space system) is a color matching system used in Europe. The so-called RAL CLASSIC system is mainly used for varnish and powder coating.