Professor Jim,

You know So much about so many things!  Thanks for your insightful dispatches--I always learn something new from you.



On 2/2/2019 11:02 AM, James A. Perkins wrote:
[log in to unmask]"> Hi Gail,

Sounds like you need to get more information from your client.

The most important question is whether they plan to print this job entirely in CMYK or if they plan to use the actual PMS 377 green colored ink. As you probably know, Pantone makes inks in a wide range of colors. These colored inks (also called spot colors) can be printed instead of CMYK. My favorite example is the FedEx envelope. The FedEx logo uses two very specific PMS colors, a purple and an orange. All of their envelopes are printed using the PMS purple, PMS orange, and black ink (for most of the text). There is no CMY. This would be a 3-color print job (black plus 2 PMS colors of ink). As Karen pointed out, it’s also possible to print a PMS color of ink in addition to CMYK - i.e., a 5-color print job

If they are indeed using the PMS 377 green ink, then follow Karen’s advice about creating a separate channel for that color in Photoshop. Anything painted on that channel will end up on a separate printing plate during the color separation process.

If they aren’t using the actual PMS 377 green ink, then they may be trying to simulate that PMS color using CMYK. I’m guessing that’s the case since they gave you a CMYK breakdown. Depending on the specific PMS color, the CMYK may or may not be very close to the actual PMS color ink. For example, if you tried to print the FedEx logo using CMYK, you could probably get pretty close to the purple but the orange wouldn’t be close at all. Most vivid neon colors can’t be reproduced in CMYK and require the use of spot color inks.

The other thing you need to find out from the client is what type of paper they are printing on. It doesn’t have to be the exact brand, but are they printing on coated or uncoated paper? Ink soaks into the fibers of uncoated paper. Better quality papers have a light coating on the surface that prevents the ink from soaking in. This can have a dramatic effect on the appearance of the ink when printed on different kinds of paper. For this reason, Pantone actually manufactures different inks for printing on coated or uncoated paper. When you select the color library in Photoshop or Illustrator, you have to specify if you want Pantone Solid Coated (PMS 377 C) or Pantone Solid Uncoated (PMS 377 U).

Because they are formulated differently, the coated and uncoated inks actually look different on screen, but should appear the same once printed on paper. The CMYK equivalents for the coated and uncoated inks are also different. This may explain some of the variation you are seeing in the CMYK equivalents of PMS 377 (although I just checked the Pantone color picker online and neither 377C or 377U is close to the numbers your client gave you. Odd).

There’s one other thing that can affect the CMYK equivalent of a Pantone color. After you select a PMS color from one of the color libraries in Photoshop, you can click on the “Color Picker” button and go back to regular RGB mode. If you are working on an RGB file, this will let you paint the equivalent of the PMS color in RGB. The hexadecimal value of the color (728f41) is just a different way of expressing RGB value. For example, hex 728f41 is the same as R=114 G=143 B=65. When you convert an RGB image to a CMYK file in Photoshop, the conversion of each RGB value to a CMYK value is controlled by the the RGB and CMYK Profiles you have selected in your Color Settings (under the Edit menu). A single RGB value (i.e., a single Hexadecimal value) can have many different CMYK equivalents depending on these color settings. Here’s an example:

I normally work with Adobe RGB (1998) as my RGB color space and U.S. Web Coated (SWOP) v.2 as my CMYK color space.
With these color settings, a Hex value of 728f41 is equal to a CMYK value of 66  24  100  7.

Then I go back into Color Settings and change the CMYK profile to U.S. Sheetfed Uncoated v.2.
I reopen the color picker and, even though the Hex/RGB values are still the same, the CMYK values are now: 64  16  100  7

Not a huge difference, but still a difference. This subtle difference is all because of the difference in printing technology between a sheetfed press printing on uncoated paper vs. a web press (SWOP) printing on coated paper.

Probably more information than you needed, but is underscores why you need more info from your client and why it is that CMYK values can vary even when the PMS or Hex number is the same.


James A. Perkins, MFA, CMI, FAMI
Board Certified Medical Illustrator
Fellow, Association of Medical Illustrators

Professor and Graduate Director
Medical Illustration
College of Health Sciences & Technology
Rochester Institute of Technology
CBET 75-2129
153 Lomb Memorial Drive
Rochester, NY 14623

From: SciArt-L Discussion List-for Natural Science Illustration- <[log in to unmask]> on behalf of Gail Guth <[log in to unmask]>
Sent: Friday, February 1, 2019 6:09 PM
To: [log in to unmask]
Subject: Re: [SCIART] a Pantone color question

Good info, Karen! My fan set is ancient, I almost never use it so I don't bother with updates; Photoshop is up-to-date. thanks for the separate channel suggestion!


On 2/1/19 5:28 PM, Karen Ackoff wrote:
Pantone color sets are updated every year. How old is your set? Or, how old is Photoshop? Be sure to tell the printer that you are using that specific color. You need to make sure you have a channel set up for the color. That way, regardless, the printer can separate out that color as he’ll need to ink the press with Pantone 377. So if the file is CMYK, it will be CMYK plus Pantone 377 - a 5-color run. Won’t matter what it looks like on screen (which isn’t going to match any way - your monitor is RGB).

Sent from my iPhone

On Feb 1, 2019, at 3:00 PM, Gail Guth <[log in to unmask]> wrote:

Hi, Everyone -
I'm doing a small job for a client, and need to match their official color, which is Pantone 377. She gave me CMYK numbers as well: 47-7-76-0.

In Photoshop, entering those CMYK values in the color picker produces a much lighter green than I am seeing in their printer materials, and lighter than what I'd like to use.

When I go to the Color Libraries and choose Pantone Solid Uncoated, and enter 377, I get the deeper color I want but the numbers are quite different (60-27-95-8, hex 708f41).

I went online to the Pantone Color picker and entered 377, I got the deeper green with the same hex number but a different CMYK value again, however it is somewhat similar to the CMYK values my client gave me (45-0-100-24)

I am confused. Why all the variation? I'll end up choosing the deeper green but I don't get all the different numbers.


Gail Guth
Guth Illustration & Design
139 Lathrop Avenue
Battle Creek, MI  49014-5076
[log in to unmask]


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Chris Gralapp, MA, CMI, FAMI

Medical/Scientific Illustration

eyeart at


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