Difference Between 4 Color Process Printing and Spot Color Printing

Many mistakes are made when spot colors are mixed in with 4 color process (CMYK) colors and then sent to press. It's actually quite common for companies to save money by running a large 4 color process (CMYK) print job and then 'overprinting' the stock with spot color black 'text only' plates. I work with a number of publishers producing multiple-language books who use this technique. They overprint different black language plates onto the same pre-designed color books. When this happens it is the responsibility of the designer to ensure that all overprint settings are correct and that all text has been colored with the '5th color' swatch (usually with black set up as a spot color). This is jumping the gun, though, so for now let's just focus on the basics of the two processes. Spot color printing creates brighter, more vibrant results, but with a smaller color range. When printing in single (spot) colors, a single color ink (normally with a Pantone reference number) is applied to the printing press roller. If there is just one color to be printed, there will be a single plate, and a single run of the press. If there are two colors, there will be two plates and two runs, and so on. The colors are layered onto the paper one by one. Spot color printing would be typically used for jobs which require no full color imagery, such as for business cards and other stationery, or in monotone (or duotone etc) literature such as black and white newspaper print. 4 color process printing involves the use of four plates: Cyan, Magenta, Yellow and Keyline (Black). The CMYK artwork (which you will have supplied) is separated into these four colors – one plate per color. The four CMYK inks are applied one by one to four different rollers and the paper or card (‘stock’) is then fed through the printing press. The colors are applied to the stock one by one, and out comes the full color (4 color process) result. Here is an example of 4 color process printing and three examples of spot color printing. There is a lot of versatility in designing for a spot color print run - experiment and see what results you can achieve! If the plates are aligned correctly on the press, the registration is accurate, and the result is sharp and clear. If the plates are misaligned, the registration is inaccurate, and the result is blurred and poor. This teaches us that no matter how good the artwork that left our studio was, the project can still be messed up by a less-than-conscientious printing company. For potentially expensive print runs it is wise to press-pass the finished product, which means actually standing at the end of the press and checking the quality of the finished product as it comes out of the machine. If you look at a full color magazine through a magnifier, you'll see that all the colors are made up of CMYK patterns, as shown by the above image. If you look at an area of spot color through a amgnifier, there will be no screen - it will show an area of solid, unbroken color (unless the grayscale or bitmap image it is applied to has a halftone screen of its own).