Help with an Experiment

One of our Forum users would like help with an experiment with matching LAB values in his PANTONE swatch book.

Here are the details:
Hello everyone,

I use an X-rite 939, and so do our various print vendors. Over a year ago, my company’s major client had a color complaint on a printed piece, stating that it was over "a half a shade" off from their Pantone® books. I then delved into figuring out what "a half a shade" meant to them. Long story short, my company and our print vendors are solely using L*a*b* values now, with a maximum deviation of 2.0 DEcmc (with some exceptions) via X-rite. Nowadays, when our #1 client has a problem, we show them the numbers, and remind them that they agreed to the science of the 2.0 tolerance.

For the most part, all was well, although our printers have difficulty with some colors (the DeltaE might be like 3.5, but visually you can’t see any difference, or PMS 285 was finally perfected by using different ‘imitation’ ink bases, for example). But then THIS happened…

Customer rejects job based on color. It should be PMS 267C but it doesn’t look like it, they say. Because I keep samples of all litho labels until a week after the ship date to the customer, I pulled the samples and shot ‘em. The print vendor was getting numbers between 0.45 and 1.30. I was shooting numbers from 0.60 to 1.11. So we were both in the ballpark. Then I pull out the Pantone book, and YIKES!!!!!! WOW was that color different! I shot five, count ‘em, FIVE Pantone books (four coated and one color bridge), two of which were opened for the very first time. One was the book from the client. The numbers were coming up around 1.7, 1.9 etc… I’ve shot PMS books before and usually they’re well under 1.0 in their L*a*b* values. In addition to PMS 267 being pretty off in the book, it was also off to the Red/Blue side. Our 0.60 labels were slightly to the Yellow/Green side, but pretty much on the mark. So actually, the colors appeared to be off by close to 3 DEcmc, because they were on opposite ends of the color spectrum.

(Bored with this yet?)

The solution, of course, is if they like the color that’s in their Pantone book, we take the L*a*b* numbers from THAT and create a custom color based on the numbers. But I foresee a WHOLE bunch of hassles down the road with this idea. Not sure yet how this is all going to pan out.

AND NOW FOR THE EXPERIMENT.

I’m curious if YOUR Pantone 267C in your book is way off from the actual LAB values. According to our X-rite QA-Master II v 8.2.1 software with the stock Pantone 2005 C library, the values should be: L*=30.30 a*=35.52 b*=(-52.44) and C*=63.33 h*=304.11. We set it up as DEcmc, l:c 2.00/1.00, commercial factor 1.0. Illum./Obs.=65/10

Would you please shoot ‘em for me using the same settings above and report your results? I’m anxious to find out if Pantone pulled a boner on that color, or if X-rite had the LAB numbers wrong or something.

Appreciate any help I can get—thanks! 

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