Friday, 26 October 2012


In offset printing, a spot color is any color generated by an ink (pure or mixed) that is printed using a single run.
The widely spread 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.
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 are sometimes referred to as 'spot colors', as they share the characteristics of requiring a separate lithographic film and print run.
Basically, an ink colour is ready-mixed to produce a particular colour, as in Pantone® 032 below.

So if you were producing a 2 colour card with, for instance, Black as the main colour for text then a 2nd Pantone® colour would be chosen from a colour swatch.
To produce this job would entail making 2 sheets of film which would then be used to make 2 printing plates for the press.
The more spot colours used, the more film and plates are needed, hence the increased costs.
To keep costs down it's possible to create tints of a spot colour without needing extra film or plates. The example (shown below) consists of Pantone® 032 at: 100% + 50% + 25%.
These 3 'shades' would all be on 1 piece of film & 1 plate.

100 %                 50%                25%

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.
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®.


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.
Adding a Pantone colour to your normal CMYK is a great way of achieving colours which simply are not possible with 4 colour  process printing. The example above from the Print Handbook is a great example of this. The Pantone here is a vibrant red which simply wasn't possible using just CMYK inks.
It's also possible to use a metallic or fluorescent ink which CMYK can get nowhere near in impact. It's a great way of adding an extra little something to your project.

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