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Managing Color for Consistent Customer Approval

(July 2008) posted on Mon Jun 30, 2008

Your command of color viewing and matching is critical to client satisfaction. Discover how to identify and remove the variables associated with these processes.


By Mark A. Coudray

The mesh count, tension, off-contact, squeegee durometer, and squeegee pressure all have a bearing on what color looks like. If you use a wire-wound drawdown as your control, the final printed piece will vary in direct proportion to the ink deposit’s thickness. An ink film thicker than the control will color shift to the blue shade. Thinner deposits than the control will color shift to the yellow shade.

More pigment particles reside in the thicker ink film. Light hitting the film is absorbed and reflected back. The thicker layer scatters more of the longer wavelengths of light, resulting in more blue and violet frequencies returning to the viewer. That’s why we detect shifts to the blue side from the control. Think of a swimming pool viewed from above. The shallow end is aqua (more yellow) and the deep end is darker and bluer. The color changes continuously from the shallow end to the deep end. The same is true with our ink film. Some colors are extremely sensitive to this, such as neutral grays, tan, beige, light blues, and pinks. Generally, the lighter the color, the more pronounced the shift in color.

When delivering a color match, I almost always ask for a physical chip of the color I’m being asked to match so I can have a known target to which I can adjust. The formulas in the Pantone book are a starting point only. There are simply too many physical variables for us to stick to just the formulas.

Lastly, when submitting your color sample, go back to what I mentioned earlier about submitting three different samples. While the example I shared was in jest, you have a very real obligation to provide matches that define the tolerance of color change that occurs during your run.

Printed color constantly changes. As temperature changes during the day, mesh tension drops, and your squeegee becomes dull. Today’s mo-dern color-measurement instrumentation is relatively inexpensive and very accurate. With only moderate effort you can quickly determine how each of these variables works, and how you can make them work in concert to cancel each other. Measurement is the key. Without it, approved color becomes a very small bullseye that is very difficult to hit and maintain. Using the Delta E measurement function you can establish a defi-nitive value that you can set in advance. Your client will then have an additional layer of confidence knowing you are monitoring and adjusting machine drift as it occurs.

 

Color commentary

Color matching and approval can be as much science as it is witchcraft. It’s been the bane of many a printer over the years. Color is always subjective, even when we have precise instrumentation. There are three main ways for dealing with color rendering. They are perceptive, relative, and colorimetric. The same color looks different when viewed under each of these parameters.

Color viewing and matching are complex processes. Education and communication will help you solve problems associated with these tasks. The most successful collaborative relationships are those in which the printer works to educate clients and understand their objectives. Most clients are ignorant of the significant technical variables that affect how their finished work will look. It’s our job to lay a solid foundation upon which we can deliver consistent, predictable, and repeatable results that meet or exceed our clients’ expectations.

 

Mark A. Coudray is president of Coudray Graphic Technologies, San Luis Obispo, CA. He has served as a director of the Specialty Graphic Imaging Association Int’l (SGIA) and as chairman of the Academy of Screen Printing Technology. Coudray has authored more than 250 papers and articles over the last 20 years, and he received the SGIA’s Swormstedt Award in 1992 and 1994. He can be reached via e-mail at coudray@coudray.com.

 


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