So, you’re ready to go to press. You’ve designed your print book, poster, or brochure, and chosen your paper stock. What about ink? Any ink will do. Right? Not by a long shot. You have more options than you could ever imagine.
Process Inks for Full-Color Images
Back in the ‘90s when I was an art director, I learned two profound things about process color printing just from attending press inspections.
(Back then, for color critical design work, it was helpful to be on press for the printing of the various press signatures, just to make sure everything was correct. Much better to catch serious errors on press than after delivery.)
What I learned was that commercial printing suppliers can adjust the process inks to make their own mix. That is, cyan, magenta, yellow, and black are not necessarily absolute colors. One particular printer with whom I worked would add a certain amount of fluorescent ink to some of the process colors, and by so doing would make certain elements on the printed image “pop.” For instance, if the photo contained yellow flowers, a bit of fluorescent yellow would make the image even more dramatic. If you’re in a similar situation, discuss fluorescent inks with your printer.
The other thing I learned was that there could be more than four colors in a process color press run. Normally you would use transparent versions of only cyan, magenta, yellow, and black. With these you could conceivably create all colors in a full-color image. However, back in the ‘90s I learned that you could add orange and green (presumably made transparent) to create what was called Hexachrome printing. Granted, instead of producing halftones with four screened plates (back then, negatives were produced first and then plates were produced from the negatives), you would separate the color images into six colors with six negatives to produce six plates. You would then print the job on a six-unit (rather than a four-unit) offset printing press.
A similar process involved “touch plates” or “kiss plates.” These were additional plates used to accentuate a color in an image. For instance, by adding a fifth press unit with a kiss plate of a purple PMS hue, you might increase the intensity of a photo of purple flowers.
It was an expensive proposition, but it yielded spectacular results. Interestingly enough, digital presses (inkjet printers in particular) can now achieve the same results just by adding more ink reservoirs to the equipment.
What all of this does, in essence, is expand the color gamut, the number of colors offset printing, or digital printing, can produce. If you’ve read my prior blog posts regarding the difference between color produced on the computer monitor and color produced on press, you will understand. Color produced on a computer monitor is created with red, green, and blue light. The universe of distinct colors reproducible in this way is much larger than the number of distinct colors reproducible with offset ink, inkjet ink, or toner.
Colors produced via digital or offset printing are created not with red, green, and blue light but rather with cyan, magenta, yellow, and black ink or toner. This method also has a color gamut. But when you compare the CMYK color gamut to the RGB color gamut, CMYK is much smaller. That is, you can create many colors visible on your computer monitor that will not reproduce accurately when printed. They will be “out of gamut.”
What adding colors to an ink set (whether offset or digital) does is expand the CMYK color gamut so it can more closely approximate the total gamut of visible hues. This is true whether you’re using touch plates or kiss plates, or whether you’re using some variant of Hexachrome (the branded but presumably discontinued process–also referred to as high-fidelity color), or even if you’re using a 10-unit inkjet printer with multiple variants of black, multiple variants of some process colors, and even orange, green, or purple.
Talk with your printer. See what he can do for you. For a high-profile print job, it may be worth it. Keep in mind that most printers will only have one or a few of these technologies at hand. But it’s definitely worth a discussion. Also make sure you discuss with your custom printing vendor how the paper you choose will affect color reproduction.
Metallic Inks
You can also add metallics to your inkset. But be careful. These are made with a mixture of metal dust and varnish (i.e., the pigment and the vehicle). The pigment is not real gold, silver, etc. It just looks like it. Unfortunately, metallic inks can tarnish, and they are not resistant to scuffing. That is, their colors can shift, and they are not durable. But they are rather dramatic, so if your job is flashy but not permanent (maybe a promotional brochure), this might be right for you.
If you choose metallics, coat the sheet with varnish for protection. Also, print the colors on a coated sheet, not an uncoated sheet. This will preserve the metallic sheen. Also consider a “double hit” of a metallic color, as these inks can be bright but somewhat transparent. Printing an image twice will increase the perceived opacity of the ink application.
MICR Ink
This acronym means “magnetic ink character recognition.” Bank checks are imprinted with this magnetic, toner-based material, and the bank numbers can then be read automatically with character recognition software. Regular toner will not work.
Invisible Ink
Actually, this is just clear ink, but you can print security information with it. For example, if you want to minimize the chance of fraud or counterfeiting, you can print information on a document that cannot be seen or that can only be seen under certain light (such as UV light). Some toner-based digital presses (such as the Kodak NexPress) have extra press units that can be used for security inks. If you’re in the business of producing passports, for instance, you might find this information useful. On passports, UV light can make printed elements of the document (rendered in special inks) either appear or disappear.
Security ink is also useful if you’re in the pharmaceutical field. When used in the packaging of pharmaceuticals, security ink can ensure the accuracy of the drug the package contains and avert sickness or death.
Security inks are a perfect match for digital printing technology, since they can take advantage of the “one-off” capability of digital custom printing. Whether you’re printing a passport or a blister-pack for a new medicine, chances are that you’ll want each product package to have a distinct serial number (which is the perfect task for a digital printing press).
Food-Safe Inks
If you’re producing packaging for food (let’s say a folding carton for fine chocolate or even a box for a frozen dinner), it’s important to know that your custom printing inks are “food safe.” That is, the US Food and Drug Administration must certify that there is no “migration” of printing inks into the food the package contains.
Part of the safety precautions involves the interior wrapping (such as the bag that contains the wheat crackers or cereal within the outer carton), but beyond this, the inks used to print the box of crackers, or the plastic bag the bread comes in, or the cardboard container for the frozen dinner—all of this ink and all of the cover coatings must be non-toxic.
What You Can Learn from This Discussion
Ink choice is not a given. You have a lot of options. However, some of these options may be expensive, and not all printers can work with all of these inks.
That said, given the development of digital commercial printing (both inkjet and toner-based) over the last 30 years, you now have a lot of choices for both static printing (with all images being the same) and variable data printing (with all images being different, such as the security numbers on pharmaceutical packaging). If you’re printing something out of the ordinary (even something like a scratch-and-sniff product, or a product with inks that smell like food or perfume, or lottery tickets with scratch-off inks), specialty inks might just be what you need.
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on Tuesday, October 6th, 2020 at 2:23 pm and is filed under Inks.
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