There are a lot of proofing options. Clearly. You have inkjet, laser, press proofs, and on-screen soft proofs. Which do you use and when?
Proofing Options: Choosing Color Fidelity vs. Speed
I like to think of the four proofing methods as a set of complementary tools. Each has attributes the others don’t. The first variable to consider is your need for color fidelity.
A screen proof, virtual proof, or PDF proof is the least faithful to the color on press. Even though a computer monitor can be calibrated to match an offset press, the image on screen is composed of red, blue, and green light, while the color on press consists of various percentages of cyan, magenta, yellow, and black ink. When mixed, red, blue, and green light create white. In contrast, CMYK inks mixed in equal amounts yield black. So, in general, I’d advise against matching color from monitor to press.
That said, soft proofs are great for checking the completeness of a page (confirming that all elements are present), the margin, trim, folios, etc. And they show up immediately since your commercial printer sends them over the Internet. The same cannot be said for hard-copy proofs, which depend on FedEx, the mail, or a courier for transport.
On the opposite side of the spectrum, high-resolution inkjet proofs have the greatest color fidelity. You can easily identify them since most will come to you on thick, gloss stock. With a loupe, you will see that images are made up of tiny spots of color, unlike the traditional rosettes of halftone dots, which you’ll see with a loupe on an offset printed piece.
These proofs are almost continuous tone in appearance. They are fingerprinted to the commercial printer’s press, so they are just about as color faithful as you can get. They are expensive, but if they keep you from making a mistake in color, you can consider the expense to be more of an investment. Choose these for photos, advertising proofs, and the like.
Laser proofs are good for checking copy position and completeness. You can see where all design elements will fall on a page. These low-res proofs are called “position proofs,” in contrast to the ink jet proofs, which are called “contract proofs” (because they are a contract between your custom printing vendor and you, committing the commercial printer to match the color on press).
Press proofs (which are either a separate press run of your job to yield a small number of “test” copies, or an actual press inspection you attend while the live job prints) are completely color faithful. This is true “WYSIWIG” (what you see is what you get). You can tweak color on press if you attend a press inspection. However, any major color changes will require new printing plates (which will add to the cost of the job).
Putting All the Proofs Together: A Case Study
Here’s a case study of a book I designed. This explanation will show when to use which kind of proofs.
The Job Specifications
The book had a four-color cover with ads on the inside front, inside back, and back covers. After the cover came the four-color front matter (44 pages of ads and client photos), and then a two-color directory (a listing of companies with company descriptions, contact names, and phone and web information).
The Selection of Proofs
I received an inkjet proof of the cover and front matter. Both were produced on thick, gloss stock, with pages taped together into four-page signatures. The color was created with cyan, magenta, yellow, and black inkjet inks. The proof was to be considered a “contract proof” (and it was, in fact, color faithful).
For the directory pages, I received a color laser proof (printed on both sides of the sheet—unlike the inkjet proofs—and bound into 16-page signatures plus one 4-page signature). With a loupe I could see a dot pattern (but not a rosette) showing that the PMS color had been simulated with CMYK toners on a laser printer. The proof did not show an actual PMS color (the directory portion of the book was to be a two-color print job) since proofing devices can only simulate match colors with process color builds.
The color was way off, but since I had specified a match color (PMS 2607) plus black ink, I knew that the proof color didn’t matter. I just needed to check the color breaks (confirm that all elements were noted either in color, or black, as appropriate) and the position and completeness of the copy. On press, the commercial printer would add pre-mixed PMS 2607 ink to one press unit, regardless of how the proof colors looked.
There were errors in the front matter. Four ads that had been surrounded with rule lines when I submitted the InDesign file no longer had rules around them. All color work, on the other hand, was completely color-faithful. So I asked the commercial printer to put the rule lines back into the file.
(We were working with InDesign files for the front matter and cover, due to their complexity, and a press-ready PDF for the directory, since it was simple text on the page. Therefore, I asked the printer to make the corrections to the front matter himself. For any changes to the directory, I would have just sent the custom printing supplier a new press-ready PDF.)
Since the commercial printer would be adjusting the InDesign file by adding rule lines around the ads, I needed to see proofs. I wanted to make sure nothing else happened to the files. All of the other changes had to do with alignment of pages (related to trimming of the proof rather than positioning of the art on the page). I didn’t need to see proofs of these pages.
Since I had approved the color in the first set of proofs, and since time was of the essence, I requested PDF proofs of only the affected pages (not the entire front matter section). This way, the commercial printer would be responsible for the accuracy of all pages other than the four new PDF pages I had requested.
Once the inkjet, laser, and PDF proofs had been approved, any further proofing would have required a press check. Since the job only required “pleasing color” and not “critical color,” I decided not to request a press check.
In addition, since an approved inkjet proof is a “contract proof,” the commercial printer was contractually bound to match the color, content, trim, margins, etc., of the inkjet proof of the front matter of the book. If a problem had occurred, it would have been the commercial printer’s responsibility to correct it.
This entry was posted
on Monday, February 27th, 2012 at 5:40 pm and is filed under Book Printing, Digital Printing, Offset Printing, Prepress, Proofing, Soft Cover Book Printing.
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