Quoted from PinballKen:I work with the most advanced printing presses in the world and color matching can still be a task. Ink quality, quality of the medium being printed on, and other factors make it more challenging than most would believe.
Tell me about it, I was an ink formulator at a silk screen plant, I mixed ink for the big TA Firebird hood decals and many other things. I would follow the formulas exactly and not match the color samples and that was using the primary inks right from 3M. Then I switched to off set, roto and finally web off sets as a press crew member. In the 30+ years I was a printer I helped print 10's of billions of consumer boxes, Cheerios, Trix, Puffs, Bisquick, Pillsbury cake, 3M VHS boxes and I even helped print the Wheaties box when the MN Twins won the World Series to name just a few. Color matching on the off set, roto and webs was not a problem because that was always determined by the dots on the cylinders for the roto and the burn on the plates for the off set and web presses. Silk screen was ALWAYS a problem. The digital printers are a whole different story.