In this day and age, one would expect to be able to accurately proof anything and everything. You can get an inkjet proof of a banner (perhaps in a smaller size than the final product), and it will be color faithful. You can request digital bluelines of a book that will be offset printed. In fact, you can even get a single copy of a digitally printed book (cover and text) that will be exactly the same as the final copies your printer will deliver.
I thought about this recently when a print brokering client received a digital proof of a foil stamped case-side for her annual hard-cover directory, a 576-page tome on government and Congress. Clearly, a digital proof of such a physical process as foil stamping would be several steps removed from the accuracy I had grown to expect. Then again, in prior years she had received no proof, just a foil stamped case without its book.
The whole process made me think of what proofing processes were more accurate and which were less so.
Spot-On Proofs
Any proof printed with the same color set as the final product will be very close to accurate. I qualify that because the substrate will make a difference, and not all digital proofs are produced on the same paper as the final job. For instance, if you specify a warm press sheet (yellowish-white) and the digital proof is produced on a cool-white (blue-white) paper, the ink colors in the final printed product will be different from what you will see in the proof.
Moreover, this level of color accuracy assumes that the digital proof (produced with cyan, magenta, yellow, and black inkjet inks) will be followed by either an offset press run using the process colors or a digital press run (which either uses only 4-color process inks or augments this initial color set with a few more hues).
If your final offset printed product will be produced with spot colors (also known as PMS colors or match colors), the proof will not exactly match the final product. For instance, my book print brokering client, noted above, will have a dust jacket on her case-bound book. It will be offset printed with one PMS color plus black. The proof she received used CMYK inkjet inks to simulate the green PMS color. The proof showed the placement of all design elements and color but was not color faithful. It was only a close approximation.
A similar situation occurs when you proof a duotone. If you create a duotone on press using a halftone of black and a halftone of a PMS color, your digital proof (which uses a CMYK color set) will not match the final printed duotone.
So What Can You Do?
Fortunately, there are things you can do to avoid a huge surprise when your books, brochures, or other jobs arrive from your printer.
Duotones
While you can’t proof a duotone accurately, there are books you can review and online color curves you can apply to a particular halftone. In this case, you’re basically choosing a sample of what you like and then recreating the duotone by copying the Photoshop “levels” or “curves” settings for both the black halftone and the PMS color halftone that comprise the duotone. Depending on the quality of your initial photo, this will be more or less color faithful, but it’s still a gamble.
Plan B is to attend a press check on-site at the printer’s plant. This way, you can talk with the press operator to discuss your goals and then make minor color changes on press while the job is running. This can be expensive. Furthermore, you may just not be able to achieve the exact results you want. Or, and even better, send a printed sample of a duotone image to your printer to show him the exact effect you’re after. Then let him adjust the actual photo from your print job to match the sample.
Foil Stamping Proof
To get back to my client’s case-bound book, reviewing the digital proof of the case side is prudent because it shows exactly where the foil stamping will be positioned on the book’s front cover, back cover, and spine. This way there’s no chance of any text element’s being too close to the edge of the book.
After that, seeing a copy of the foil stamped case side before the book blocks are hung on the binder’s boards will avoid any shock of seeing an error on the final printed and bound job. While my client would have to pay for a new die and for an additional foil stamping process if she found an error, she would not have to tear the covers off the books and redo the covers. (In this situation, reviewing a single foil stamped case side is like reviewing a single F&G—a folded and gathered but not bound or trimmed book. You’re just seeking to avoid any horrible shock before the job is completely done.)
What’s the Final Take-Away?
What this really teaches us is that no proof is an exact replica of the final job (except a digital proof of a digitally printed job produced on the final stock).
Here are some rules of thumb:
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- The closer the substrate of the proof is to the substrate of the final job, the more accurate the proof will be.
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- The more closely the final printing process is to that of the proof, the more accurate the proof will be (digital proof to digital final press run).
- And the more closely the inks used in the proof resemble the inks used in the final printed product (CMYK proof and CMYK final), the more closely your proof will match your final job.
Beyond that, the best you can do is state clearly your goals for the final printed product and then back up this description with samples of other printed jobs you like. It’s always a bit of a gamble.
This entry was posted
on Tuesday, July 15th, 2014 at 3:39 pm and is filed under Proofing.
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