Scratch-off Inks and Map Printing
A print buyer recently contacted the Printing Industry Exchange asking about scratch-off maps. The publisher referred her to me, and since I was only somewhat familiar with the process, I did some online research. I had been aware of the lottery ticket scratch-off ink, which I had understood to be a latex-based product, but I was surprised to see how there was a growing interest in using scratch-off inks for maps as well.
This is what I learned, first regarding the reason for the growing interest.
First of all, if you print a base map (let’s say an image of the United States--state by state--or even the world--country by country), and then you block out certain sections of the map with silver latex printing ink or UV ink, you can reveal whatever information is on the base art layer by scratching away the metallic ink with your fingernail or a coin. If you use such a map as a record of your travels, you will have a pictorial reference showing exactly where you have been (a memento to retain for a lifetime).
What makes this useful on a functional level, if you are the designer of such a map, is that you can include special information about each state or country on the base printed layer that will intrigue the user as he or she reaches each goal (each state or country) and scratches away the covering latex or UV ink.
Furthermore, based on my research I have noted that UV inks are being used for the silver (or other color) blocking effect since they are "cured" rather than dried. That is, they are instantly polymerized (solidified from their initial viscous state) using UV light. Therefore, a larger than usual amount of pigment (relative to solvent, or vehicle) can be used with UV printing than with traditional printing inks. Because of this, the inks will not only sit up on the surface of a substrate rather than seeping into the paper fibers, but less ink than usual can be used to successfully mask anything already printed on the substrate. This is ideal when you’re covering a base image--such as a map with printed text and images--using scratch-off ink.
More specifically, based on my research, it seems that traditional inks contain up to 40 percent solvent (the vehicle that makes them fluid and that dries through absorption, oxidation, or evaporation leaving the pigment behind). In contrast, with UV inks the liquid is both the pigment and the vehicle, so less liquid is needed to produce superior blocking of any preprinted material (as noted on www.quora.com by Kaicheng Liang, biomedical engineer, electrical engineering PhD student).
These UV inks are also more environmentally sound, given the absence of solvents (as per Kaicheng Liang).
In addition to "scratch-off ink," other names for this particular kind of ink include "flexo silver ink" and "flexo ink."
So in terms of its popularity, just as "scratch-off ink" initially became the gold standard for scratch-off lottery tickets due to its functionality and the user’s desire for financial gain, the scratch-off map is becoming a vehicle for personalization, offering an entirely unique version for each participant, as he or she visits a particular state or country and scratches off the ink to create a map of his or her journey.
What is an Imposition Proof?
Back in the day, imagesetters in print shops produced negatives from which printing plates were "burned." If you went into the prepress unit of a print shop you would see men and women working over light tables, "stripping" together negatives of type and photos onto plastic yellow sheets called "goldenrod." Their goal was to position everything from each printed page in perfect alignment, with nothing missing, so that one plate could be photographically produced for each of the four process colors.
Prior to burning the plates, the prepress employees would expose chemically treated, light-sensitive paper through the composited negatives to create what was called a "blueline." An entire flat of pages (for example, eight pages, or one side, of a 16-page press form) would be exposed and developed, and then folded into a booklet (as an indication of exactly how the printed and folded press signature would look).
The customer would review this blueline to make sure one last time that everything was in position and nothing was missing. This was not the time to edit the text, since corrections at this point would be costly.
If you fast forward to the present, almost all printers now image press-ready files directly to printing plates. Therefore, the traditional blueline made from negatives has ceased to be necessary; however, it’s still important to see a proof before the printer produces the final printed copies of a job.
These days, printers often provide what is called an "imposition proof," which is an inkjet proof of all pages on one side of a press form, usually taped back to back to an inkjet proof of the other side of the press form, and then folded and trimmed to simulate a folded press signature. This will look exactly like the final printed product (albeit not on the final paper stock).
If your job entails your reviewing such a proof, you need to check it carefully to ensure that no type elements, photographic elements, color blocks, etc., have been accidentally omitted. This is the final stage. It is also not the time to edit type, since this will be costly. (Granted, it won’t be as labor intensive or expensive as it was when new negatives had to be produced and re-stripped, but it still should be avoided.)
One thing you’ll notice, if you request such an imposition proof, is that it is of a lower quality than you might expect. This is also called a "position proof," and the goal is not to see all elements of a job in perfect resolution and color. Rather the goal is to ensure the proper position (placement and completeness) of all elements.
For more precise proofs, you might want to request a high-resolution, contract-quality inkjet proof. Regardless, keep in mind that few processes will show the exact halftone dot structure that will appear in the actual printed job. Most proofs are "continuous tone," or "contone" proofs.
In the 1990s, when I was an art director, there used to be a proof called the Kodak Approval, which showed exactly how the screened halftones would look. Fuji made similar equipment. Unfortunately, both are rare or even non-existent these days.
And since the trend seems to be increasingly toward digital printing, this does not surprise or worry me. After all, if the final printed job will be produced on a digital press (laser or inkjet), it stands to reason that the final color-accurate contract proof will be produced on similar equipment.
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]