Spot and process colours

Spot Colours

Once you get your head around the difference between spot and process colours it is very easy to understand.

If you are re-decorating your house you would probably visit your local DIY store and pick up a colour swatch showing all the available paint colours printed in a swatch.

You could then make your choices and call back into the store and supply them with the relevant information for them to either supply off-the-shelf, or mix the paint to your requirements.
It’s very similar when choosing a spot colour.

The main difference is that your local printer is unlikely to give/lend you a colour swatch, as these are very expensive to purchase and have to be kept in a light-free place to prevent fading of the colours.

What is a spot colour?

As with the paint example above, a spot colour is basically a pre-defined colour that can be reproduced at any time. There are many different colour references but the industry-standard formulas are provided by Pantone®.

Many of the standard colours have names (Fig. 1), e.g. Pantone Purple, Pantone Process Blue etc., but the majority are referenced purely by numbers (Fig. 2). Incidentally, the ‘C’ stands for Coated, more on this later.

Screen Colours

One of the things that causes the biggest problem is when choosing a colour from an onscreen swatch, as above. Most people, understandably so, expect the printed colour to look the same as the onscreen colour. Some colours will print quite closely to what is seen onscreen, whereas others will be a mile out.

Without getting too technical about this the problem stems from the fact that we’re all using different monitors, at different resolutions and to accurately display the correct colour would entail the user in having a Pantone colour-calibrated system. This is beyond the realms of the majority, hence the uncertaincy when choosing an onscreen colour. PC’s and Mac’s (Apple) both use different colour tables to display onscreen colours (in RGB) which compounds the situation.

Here’s an example:

The Pantone Violet block on the left is taken direct from a Pantone colour swatch. On my PC screen this colour looks blue. The Pantone 2603 swatch, which should show as a purple colour onscreen, is more accurate to what Pantone Violet actually looks like.

So, if you were to choose Pantone Violet from an onscreen swatch, you would understandably expect your job to look blue, when in fact it would actually print more on the purple side.

This is why, when choosing colours, it is so important to use a Pantone swatch as the results could be disastrous to your project.

Tip! If you don’t have access to a colour swatch, then the best way around this problem is to print a few colour blocks to your laser or inkjet, mark the colour you desire and send this sample to your printer, who will be able to match quite closely using a swatch.

Remember: your monitor mixes and displays colours in Red, Green & Blue (RGB) so it won’t be able to give you an accurate rendition of a Pantone spot colour.

Important: different surfaces and materials accept ink onto their surface at different values, e.g. ink will ‘sit’ on a business card better than a letterhead, which will be more porous, so it’s possible you may get a slight colour variation on different materials.

What does the ‘C’ character mean as in Figs. 1 & 2 above?

As stated earlier the ‘C’ stands for Coated, so if you’ve chosen a Pantone Solid Coated swatch for instance you may see any of the following letters after the number – C, CV, CVC. If you’ve chosen a Pantone Solid Uncoated, then you would see ‘C’ replaced with ‘U’.

If you are having a full colour gloss brochure produced for instance, then your printer would use a ‘coated’ ink, designed to sit & dry quickly on a ‘coated’ surface, as with gloss finishes.

If you are having general business stationery, business cards, letterheads, invoices etc. then you printer would use an ‘uncoated’ ink, again specifically designed for this type of material.

For all intents and purposes it doesn’t really matter which swatch you use. The important thing to remember is: if you are using more than one colour, make sure it is selected from the same swatch type the original colour came from. This is very important. If you mix swatches, then it is very probable one or more of your colours will go missing at the print stage.

CMYK Colours

You’re probably aware of the fact that CMYK stands for Cyan, Magenta, Yellow & Black. (K was used instead of B, so as not to confuse people into thinking it meant blue).

The following example shows Pantone 2603 as a spot colour and also how CMYK would be used to ‘make up’ the same colour.

Pantone 2603 shown as a spot colour . . .

. . . and now, Pantone 2603 shown made up using a CMYK ‘split’.

69% of Cyan
100% of Magenta
0% of Yellow
2% of Black

As you can see, the above example uses 3 of the 4 primary colours to produce Pantone 2603

Why bother with spot colours if I can achieve the same results with CMYK?

Basically, costs determine which format should be used. Each system has its pros and cons.

A 2 colour press, a machine that has 2 colour units, is much cheaper to buy & operate than a 4 colour press, which has 4 colour units.

The 2 colour press is much quicker to set up and get to operating speed than the 4 colour equivalent.

Let’s say you ordered 200, 2 colour business cards. This job would typically be run on a 1, or 2 colour press. (If run on a 1 colour press, then the job would have to be run through the machine twice, to put the 2nd colour on). This machine is quick to set up, and just as importantly, quick to ‘wash-up’, or clean the rollers where ink had been in contact. Putting the job on a 4 colour press is obviously going to take much longer to set up, and wash up so the obvious economics would suggest this is not the ideal route. Also with a 4 colour job, 4 printing plates are required as opposed to just 2 plates for a 2 colour job.

The 4 colour press comes into its own where full-colour images are to be printed, such as in brochures, flyers etc. or anything using a colour photograph for instance. A 4 colour job can be printed on a 2 colour press but would need to be put through twice.

Sometimes a printer may decide it is more economical to run multiple business card jobs together, on one large sheet, so if there are lots of different cards, with lots of different spot colours used, then he would convert the artwork to CMYK and run the whole job as one. So, say there are 20 different card jobs, instead of doing 20 set ups on his 2 colour press, he can do just one set up and run the whole lot together. This is beneficial to the client also, as it means the job would be produced much quicker.

One downside to this process – converting artwork from spot colour to CMYK colour can often alter the colour slightly so if it is important to exactly match a spot colour then this would need pointing out to your preferred printer, as he may decide not to convert to CMYK depending on the colours you have chosen.

The above is just a very basic overview of the two processes but shows that there is much more to the printing process than many people realise.

If you have a question, or just need clarification on any of the above, then please drop us a line and we will hopefully try and answer your query. Here’s a great resource for spot colour work and colour issues which looks at typical scenarios.