Why can’t PMS colors run well in CMYK?

pantone_book_else_blakeWhen you have thousands of colors at your disposal as you design a print piece, not all of them will reproduce well in the CMYK color space. Why is that?

WHAT IS PMS?

PMS stands for Pantone Matching System, which is the international standard for ink colors when printing.  Pantone started in the early 50’s, and by the late 50’s was standardizing ink colors and producing the well-known (and well worn-out) PMS books. When you specify a color by its PMS, you are designating that a very specific color with a very specific formulation is to be used.  Many printers have presses that can handle a “spot color” if necessary. But due to the costs of additional plates, wash-ups and make-readys, many clients opt out of running a spot color, and choose to run it as CMYK, or 4-color process.

SO, WHY DOES THAT COLOR NOT MATCH MY PMS BOOK?

Many PMS colors are based upon specific colors that are not necessarily for printing, but to be used as formula colors.  For example, you’d rarely print with transparent white, but it is the base color for many of the pastel-like PMS colors you find in the books.  The problem is that in the CMYK color space, these base colors cannot be reproduced, and so you will be unable to match some of these PMS colors in 4-color process.  Take a look at the image here, where Pantone 1767 is made up of two PMS colors, one being Pantone Red mar5-pantone032, and it’s 6.2% of the mix, and then Pantone Transparent White, which is a whopping 93.8% of the mix.  This color, then, will NOT reproduce well in the CMYK color space.  Reflex Blue is both a base color and a specific PMS color, but it cannot be reproduced well in the CMYK space.  Rhodamine Red, which is similar to magenta, is just different enough that it too cannot be reproduced well in the CMYK space, but it is a base for many more vibrant red Pantone colors.  Base colors are not made up of mixes, but are specific colors unto themselves.

Another guide by Pantone that you can purchase is the PMS to CMYK conversion book, known as the Pantone Bridge, which shows you what a specific PMS color will look like in CMYK.  As a designer, or aimages (2) printer, this is a vital tool to have.  It doesn’t give you the breakdown of inks that make up a specific color, but it will show you what that color looks like, and it even gives you the CMYK values.  For example, Pantone 1485 C is a nice mustard color. But in CMYK it looks more like a dry mustard. You can see that it has 0% of cyan, 34% magenta, 58% yellow and 0% black.  When going over ink colors with a client, the Bridge book will allow you to show them how a color will reproduce in the CMYK space.  And if they don’t like that, then the option is to run that color as a spot.  However, prepare them that this will cost extra for the plates, make-ready, ink and wash-ups.

OH!  WHAT DOES THE “C” AND THE “U” MEAN?  I LIKE 1485C, BUT 1485U LOOKS BLAND.

In my most recent blog post about designing for print, with paper being the final variable, I mentioned how uncoated sheets absorb the printing dot, which can affect how the ink will appear on the sheet.  Pantone accounts for this by having two different books for coated sheets and uncoated sheets, hence the “C” and the “U”.  THE INK COLOR IS THE SAME FORMULA!  THE BOOKS SHOW YOU HOW THAT INK SHOULD APPEAR ON A COATED OR UNCOATED SHEET.  THERE IS NO DIFFERENCE IN THE INK FORMULA!  As you design your piece, the best thing is to select just the PMS color, without specifying the C or U.  Printers disregard this suffix anyway.  TIP: if you ARE running a PMS spot color, have your print services provider do a drawdown, which is a swatch of the selected color done on the actual paper that the job is running on. That will give you the actual color on the actual paper, which is better than the PMS book or on your RGB transmissive light monitor.

Understanding how PMS colors can look in the CMYK space gives you an advantage in your print design, as well as in the conversations you have with your clients.

Connect with John on Google+Twitter and LinkedIn.

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About John Prothero

John Prothero is a print professional with over 30 years experience in the print industry. Starting out as a driver delivering jobs, he worked in bindery, proofing, plating, traditional prepress (camera and stripping), scheduling, job planning, job management, account management and digital job production. His skills also run in the area of blog authorship, social media management, and lead generation and qualification of prospective clients. John is also a contributor to Rhode Island Creative Magazine, a digital publication that highlights the creative spirit of the state of Rhode Island. You can read their online issues at www.ricreativemag.com
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