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The Mystery of Spot Colors

If the word Pantone® conjures up thoughts of complex color theory, expensive swatch books, or a mysterious color system of which you’ve heard of, perhaps even used, but wouldn’t want to give a lecture on, don’t worry…you’re not alone. The truth is, understanding colors in the Pantone Matching System® (PMS) is relatively simple when you learn how they are created and how they are used.

Pantone began in the 1950’s as a printing company in New York. In the mid-60’s they began standardizing ink colors and creating reference books which ultimately became the Pantone Matching System; a system that designers and manufacturers can use as a reference to reproduce specific colors. The system has become an industry standard and primarily consists of printed swatch books for process and solid colors with a given ink formulization and L*a*b* target. L*a*b* is the widest visual color gamut and is used as the target due to common ink pigment and production variances. Though the Pantone library contains CMYK formulation references (process colors), most people reference the solid colors library (spot colors). Within these libraries, Pantone produces ink references on coated papers (C) and uncoated papers (U). The same ink will have a different L*a*b* value when it is printed on coated paper versus uncoated paper. They also produced a reference on matte paper for a short time, but has since been discontinued (guard your matte book well if you have one). X-Rite Inc. purchased Pantone in 2007.

In printing, colors are typically reproduced using one of two methods. First, and primarily, colors are reproduced using CMYK process (cyan, magenta, yellow, black). These four colors are combined to create all colors we see in graphics and images. For instance, cyan and yellow will make green, magenta and yellow will make red, etc. A similar process is used in your television or computer, which reproduces colors using RGB process (red, green, blue). However, RGB color reproduction relies on an emissive process where when more color is added the result gets closer to white. When more color is added in CMYK color reproduction, which relies on a reflective process, the result gets closer to black. An emissive process generates light whereas a reflective process requires an environmental light source. The second method for reproducing colors in print is with Pantone spot colors. The Pantone system currently uses a set of 14 base colors plus transparent white to reproduce all of the spot colors in the PMS library. These base colors include Reflex Blue, Process Blue, Blue 072, Violet, Purple, Rhodamine Red, Rubine Red, Red 032, Warm Red, Orange 021, Yellow, Yellow 012, Green, and Black. By using more base colors with a wider range of pigments the Pantone system can yield colors that are not achievable with CMYK process. A few colors in particular, like some oranges, blues, and greens, can be well outside the CMYK color gamut.

If Pantone spot colors have such a wider color gamut, you may wonder why we don’t use them all of the time. The reason has to do with practical production. A printing press is typically set up with CMYK process colors all of the time. Most jobs will be reproduced with CMYK in order to simply achieve most colors and CMYK is necessary to reproduce full color images anyway. Adding a spot color to the job involves making or purchasing the spot color ink, producing an additional printing plate, and setting up and washing up of another printing unit. All of this involves time and money. Additionally, if that Pantone color can be achieved with CMYK, meaning it is inside the CMYK color gamut, then it usually makes no sense to spend the time and money to run a spot color.

There are times, however, when it makes sense to run a spot color. If there is heavy usage of a brand color throughout a piece like a book or large brochure it may make sense to run that as a spot color for consistency purposes. Since CMYK colors are produced using four independent printing units they rely on the consistency of each unit to maintain the same color build throughout the production run. A spot color is a premixed ink in a single printing unit, relying only on that one unit for consistency. Spot colors also tend to look more smooth or solid than process colors because they are single premixed inks, whereas process colors are made from dot patterns of each of the CMYK colors. Instances where a piece uses a color outside the CMYK color gamut it can sometimes be necessary to run as a spot color in order to not compromise the design. In all cases, the number of spot colors used in addition to CMYK is typically limited to one or two. Designing a piece with process images and six spot colors is not practical to produce given the cost and limitation of the number of printing units on most lithographic presses.

When designing pieces for print it is okay to use spot colors even if the piece will ultimately be produced with CMYK; just make sure that spot colors are converted to process in the file so that your preview of the colors accurately represents what will be produced. In InDesign® spot colors can be set to process individually by double-clicking the color in the swatch pallet and setting the color type to process, or globally in the ink manager by checking “all spots to process.” Also be sure to use the appropriate solid spot color library, C or U, depending on whether the piece will be printed on coated or uncoated paper. This will help set expectations of what can be achieved in production. Pantone also produces “bridge” books that show spot colors and their equivalent process color side by side in both coated and uncoated formats–a must-have for any print designer.

If you have any questions regarding spot colors or designing for print, please feel free to contact us or call Phillips prepress at 888-ask-phil.