Our last blog post described how printing presses can simulate full colour using only four different inks: cyan, magenta, yellow and black (CMYK). Although CMYK printing is very powerful, there are certain colours it can’t mimic. These include very bright colours, fluorescent colours, and metallic inks.

These additional colours can be printed using a different type of ink called a spot colour. Spot colours are pre-mixed like tins of paint to match the exact colour required. They are very consistent across batches. As well as being used for special effects, spot colours are sometimes used when it’s very important that a certain colour (such as they key colour in a logo) is printed as consistently as possible.

Here are some situations where a spot colour might be used:

In a colour brochure that includes an important company logo. The company would like the colour of their logo to be as consistent as possible across all its publications. CMYK inks are used for the rest of the content, plus a fifth (spot) colour just for the logo.

In a simple document that only features two or three colours. Many documents only use two or three colours. Rather than print them using CMYK, it may be cheaper to use spot colours (often with the addition of black ink).

To create a special effect. For example, if you are looking for a metallic ink or a bright, fluorescent colour that CMYK can’t replicate.

Bear in mind that if you choose to use spot colours, your printer will need to have a suitable printing press. Printing CMYK plus a spot colour requires a five colour press, and not all printers have these. Extra inks will add extra costs to your job too, so this is likely to be a factor when considering whether to use a spot colour.