There can be a lot of confusion when trying to figure out whether to use process or spot colour for a litho print run.
Understanding the differences between process or spot colour and which is best for what can be the difference between a good and great final product. It can also save time, money and frustration.
Here’s a brief look at some of the main differences between the two.
What is process colour?
Process colour is the more common method for litho printing and uses a combination of 4 colours: Cyan (C), Magenta (M), Yellow (Y) and Black (K) or CMYK. Printing uses inks in the 4 colours and each colour is run through the press to produce the full colour spectrum.
What is spot colour?
Spot colours are created through a colour system, such as the Pantone Matching System®. Pantone colours are standardised to ensure that the exact required colour is achieved and are made from a palette of 18 basic colours that are mixed according to a unique formula.
All the considerations:
If the design was created using spot colours or RGB it must be converted to CMYK before going to print. If it was created using CMYK or RGB it must be converted to spot colour before going to print.
For process colour, the print file is separated into the 4 process colours with screens comprised of small dots at a different angle for each colour to make up a cohesive composite image. In spot colour tints are printed using tiny dots instead of solid blocks and create the illusion of shading. The print file is separated into the different spot colours, with any tints of a colour on the same plate as the solid colour.
The separations for process colour are transferred to a printing plate for each colour and the colours are printed on top of each other. For spot colour the separations are transferred to a printing plate for each colour and are printed to register with each other.
The resultant CMYK image fools the naked eye with the illusion of continuous tone. If you zoom in on a magazine page, you can see the CMYK dots that form the image. Spot colour provides more even coverage when printing over a large area. Some spot colours will be cleaner and brighter than if they were created in process colour.
Varying the percentages of the 4 colours produces different hues and thousands of colour possibilities. The amount of colours may seem endless, but in reality CMYK provides a limited colour range. Due to the gamut of the 18 basic colours, spot colour offers a far larger colour range and includes colours outside of the CMYK range (eg, bright red) as well as metallic and fluorescent colours.
When printing a solid colour with process inks, there may be slight variations in the colour balance that can affect the colour’s consistency. There’s an infinite amount of spot colours, so they can provide more vibrant and detailed colour as well as better consistency.
Process colour is ideal for designs that have a lot of full-colour images or those where colour accuracy and consistency are not a top priority. While it produces high-quality results, there’s a chance of colour variation. Spot colour is best when colour accuracy and consistency are crucial. They should be used for logos and brand elements that feature few colours and are the only option for metallic or fluorescent colours.