Things to Consider When Overprinting Black Ink

You have probably heard or read that process inks are transparent: that when process inks are laid over one another, they act as filters (somewhat like gelatin filters on theatrical spotlights) to subtract certain wavelengths of light and reflect other colors. This is the nature of process color printing.

However, it's important to remember that not only cyan, magenta, and yellow inks are transparent. Black ink is transparent, too.

When is this important to remember? When you're overprinting a process color image with black ink.

For instance, if you print a portion of a large initial capital letter over a 4-color photo, with a portion of the letterform extending beyond the boundary of the image onto the white paper surrounding it, the black ink overprinting the photo will look different from the black ink printed directly on the white paper. In effect, you will see the cyan, magenta, and yellow of the photo through the transparent black process ink.

One way to fix this problem is to use a rich black (a combination of process black ink with an additional percentage of magenta and cyan). Different commercial printers will have their own mixtures (ranging around a 50 percent magenta and/or cyan ink limit), and these rich blacks will be either cooler (more cyan) or warmer (more magenta).

In addition to providing thicker, richer ink coverage than process color by itself (i.e., 100% black plus 50% cyan, plus 50% magenta for a total of 200% ink coverage plus any yellow—as opposed to just 100% black), rich black ink will overprint 4-color process images (or process color screens) without creating a distinction between where they overprint the image and where they overprint the surrounding white paper. (If you specify a rich black in your InDesign file, do check the printer's proof carefully for any color problems.)

Another solution would be to manually knock out the 4-color image below any type that would otherwise cover both the photo and the surrounding white paper. To go back to the example above, most print layout applications would print black type over the photo without deleting the image below the type letterform. (This would only be true for black ink. If the overprinting type letterform were any color but 100% black, most page layout applications would knock out the 4-color inks below the overprint.)

One can override the default on most if not all layout programs to disallow the printing of black over process colors. In this case, the 100% black letter would print directly on the white paper, whether it is within the boundaries of the 4-color image or outside its perimeter. The portion of the photo beneath the letterform simply would not print.

(As long as you're printing process colors on a 4-color press, either of these solutions would cost the same; however, it would still be wise to discuss your options with your print provider.)

Inserting Facsimiles of Pages within Layout Files

Let's say you are designing a textbook, and you need to insert a copy of a form or other book page within the text as a facsimile, for informational purposes. You will want it to be as crisp and clear as possible.

You could scan the sample page and save it as a TIFF. Then you could place the TIFF file within the InDesign or Quark document, but this would give you a somewhat fuzzy image of the sample. Whether you're producing a grayscale or CMYK image, you would still be rasterizing the fonts on the facsimile book page (or sample brochure, or sample of any other printed product) by scanning them directly.

To maintain the initial crispness of the PostScript letterforms, it is much better to save the original of the facsimile page as either a PDF (portable document format) or an EPS (encapsulated PostScript) file and then place this image within the InDesign or Quark layout file. This will maintain the vector nature of the type (i.e., the mathematical curves of PostScript that exist prior to rasterizing a file, or making it a bitmap image).

While either an EPS or a PDF will do the trick, a PDF of the facsimile page will contain the font information (you can “embed” the font information in the PDF file), but an EPS will necessitate sending the printer or service bureau the fonts used in the facsimile image. That is, you don't have a font embedding option with an EPS file.

If you do choose to scan a sample page (let's say you have printed out a form and then filled it out by hand, and you want to reproduce a facsimile of this page for reference as a small piece of art within your main publication), then just make sure you scan the facsimile document at a high resolution.

I would only do this for black and white art, and I'd scan the facsimile to produce a 1200 ppi image at the final size. (That is, scan the page at full size. Then reduce the size of the image to the smaller size needed for inserting the facsimile image into your final page layout file. Reducing the scanned image will increase its resolution.)

Try scanning the image as grayscale and bitmapped (black only) to see which looks better when you have reduced and placed the facsimile image.

Tagging Text in Directories and Other Annual Publications

Here's a quick way to update publications from year to year.

Once you have completed the layout job in InDesign (or Quark), export the text as a file, preserving the layout tags. This is the metadata layout information preceding the actual text of the file.

For instance, if you have created a paragraph style sheet (noting such attributes as font, point size, additional space between paragraphs, leading, and so forth) and have applied this consistently throughout your layout file—and, if the text is one long chain (i.e., has not been cut and pasted into numerous text blocks), you can highlight all text, export it as a MS Word or text file, and end up with a tagged text file.

If you open this exported file in MS Word or another text editor, at the beginning of the file you will find the style sheet attributes. Then below this you will find the text elements of the document with each element preceded by a tag (“head 1,” “text,” etc.).

If the sales reps or editors at your business update the text directly in the Word file (let's say it's a membership directory, and some of the addresses, contact people, phone numbers, and company descriptions need to be amended throughout the year), then you can import the corrected text file right back into the new year's version of the InDesign layout file, and the text styles and attributes will automatically reappear. (That is, it will look like you have applied styles individually to all InDesign text elements.)

If you import a pre-tagged Word file into a copy of last year's existing InDesign directory file, all of the new text will flow into the directory pages (all 50, 100, or more pages), and this will save you a huge amount of time. After all, you won't need to reapply styles to each element of the copy.

For this to work well, everything should be linked (with all copy for the directory in one continuous flow). It also helps if there are relatively few style tags. In short, it's ideal for publications such as directories.

[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.]