Custom Printing: Designing for Digital Printing

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Designing for digital printing is a subject that needs regular attention these days. Digital and offset printing are not the same. While each has its benefits, they both have potential drawbacks that you can minimize based on your approach to the design of your custom printing project.

Moreover, between the quick turn-around requirements, versioned printing and variable-data printing requirements, and ultra-short print run requirements of recent years, it behooves you to study the various ways to minimize the visibility of the flaws inherent in digital commercial printing.

Sooner rather than later, you most probably will need to address these issues.

An Example

Here’s an example. In my commercial print brokering business I currently have a client who is designing a floor sample box. It is a die-cut, fold-up product with 32 separate samples of flooring (1” x 2” x .5” wood chips) inset and glued into wells in the interior panels. On the liner for the interior of the box/book, the names of the wood products are printed (or reversed out of the background). The exterior panels are printed (photos, marketing text, company address information, etc.).

For a while during the design process, all exterior, visible panels of the book/box, including the front and back covers and the spine, were to be printed in 4-color process ink. Inside the box, the liner (which covers the chipboard box structure and surrounds the die-cut wells for the wood chips) was first white with black type, then black with white type, then 4-color process to match the dark bluish-black within the front cover photo. (That is, the design of the box is an evolving process.)

All of this would have been fairly uneventful in an offset print run, barring the need to adequately dry and then laminate the heavy coverage ink. However, both the prototype for the box (a one-off sample that will convince the client to either go forward with the printer or go elsewhere) plus the extremely short press run for the box (100 or 200 copies) will necessitate digital custom printing.

Offset vs. Digital Printing

At this point it may be helpful to review the differences between offset printing and digital printing:

1. 1. Offset printing involves applying ink from an on-press reservoir to rollers, then to a printing plate, then to a rubber blanket, and then to the paper substrate.

1. 1. Digital printing involves the building up of an electrostatic charge on a drum to attract toner particles (dry toner or toner suspended in a liquid or oil), apply them to a blanket or belt, and then deposit them onto the paper substrate.

1. 1. For the most part (and to a lesser extent with coated paper than with uncoated), with offset printing at least some ink seeps into the paper fibers as it dries or is cured with UV light.

1. 1. With digital printing, most of the ink sits up on the surface of the paper.

1. 1. Offset printing is static. It cannot apply different information (such as different addresses) to each copy printed. Digital printing can.

1. For very short runs, offset printing is cost prohibitive (all of your money goes into preparation for the short press run). However, since there’s almost no prep work for digital, you can print as few as one or two copies of a digital press run.

Back to My Client’s Flooring Sample Box

So, my client needed one initial copy (the prototype). It required heavy coverage of ink, 4-color process work, gloss lamination, die cutting, gluing, and assembly. And the final production run will need all of these processes for just 100 or 200 copies (well under a 1,000- or 5,000-copy run—for instance—that might be cost effective for an offset printing job). Therefore, digital custom printing is the way to go. And the potential pitfalls of digital commercial printing will be crucial for my client (the designer) to address.

Potential Problems

Uneven Toner Laydown and Problems with Gradients

Unlike offset printing, digital printing involves electrostatic charges—noted above—that may not be even across the entire press sheet. Therefore, the laydown of toner (toner deposit) may not be completely even. This can lead to artifacts (little bits of toner here and there, marring the precise, even deposit of color) and “banding” in gradient colors (visible bands of color across a press sheet when you’re transitioning from one color to another). The unevenness will be even more visible if you’re printing on a perfectly smooth, coated press sheet.

The Solution

To reduce banding and artifacts in tints or gradations, use Photoshop to add noise—i.e., a visible texture—to the graduated screen or tint. Or use Gaussian Blur on the background screen. Also, make tinted areas smaller, or keep them apart from one another in the design.

In addition, ask your commercial printing supplier about the best length for gradients (the physical length from the start of one color to the end of the transition to the other color) and the best starting and ending percentages for the transition (perhaps 80 or 100 percent gradually reduced to 15 percent across the length of the gradation). Ideal gradations may vary from one digital press to another, or one printing resolution to another, so discuss this with your commercial printing vendor.

Issues with Cracking Toner at Post-Press Folds

Since toner (whether dry toner or toner particles in viscous oil) sits up on top of the press sheet, printing heavy coverage of a 4-color process “build” and then folding the press sheet off-press can lead to cracking of the toner/ink.

Solution

Avoid heavy toner coverage over folds, or score the press sheet before printing and folding it.

Color Matching Problems

Most digital presses either have no accommodation for PMS match colors or only a handful of match colors you can choose (such as a the available mixed colors for the HP Indigo press). Therefore, if your cyan, magenta, yellow, and black ink builds don’t match the particular corporate logo color you want, you don’t have the same options as with offset printing (i.e., printing PMS match colors using an additional inking unit on the offset press).

Solution

Keep your colors within the printable CMYK gamut (which is smaller—i.e., has fewer distinct colors—than RGB or PMS match colors). This is not a workable solution in all cases.

In general, to ensure color accuracy, ask your printer about color profiles (ICC profiles) and whether to save your images (photos) in TIFF or EPS format. The latter, EPS, will allow you to embed color profiles into the saved images.

Trapping Problems

In my own experience (and this may be in the process of changing), tolerance for movement within the digital press is not quite as precise as in an offset press. So if colors have to abut, any imperfections in paper transport can cause problems (visible white lines between colors that abut). In addition, trapping technology, in general, seems to be more comprehensive in offset lithography than in digital printing (again, this has been improving significantly). (Trapping is the intentional, slight overlapping of abutting colors to avoid white lines between them in case the ink or toner placement is not exactly right.)

Solution

Keep colors apart, where possible. Also, research trapping options for digital printing. Keep at least one common color (cyan or magenta, not black or yellow) within the two colors that trap. If you design with type printed on a solid or screened 4-color build, consider using black type on a light screen. Or reverse the type from a dark solid or screen.

Transparency Issues

Transparency (this pertains to opacity, glows, feathering, blending, and drop shadows) can cause problems (particularly when “flattening” the file).

Solution

Keep the transparency on the uppermost layer (research “stacking order” of elements in transparency). Flatten the files before handing them off to the printer. Proof the page early and often.

Issues with Bleeds

Bleeds can be a problem because digital press sheets are usually smaller than offset press sheets.

To achieve a bleed, your printed image has to extend past the end of the final-size printed page and then be trimmed off to give the illusion that the ink goes off the edge of the page. This often requires a large press sheet. Digital presses often accept press sheets that are closer to 13” x 18” than to the 25” x 38” or larger press sheets an offset press can accommodate.

Solution

Larger digital presses are being made. Ask your printer about the acceptable press sheet sizes for his press. As an alternative, find another printer with digital press equipment that can accept a “B2” press sheet (which is just under 20” x 28” in size).

If You Remember Nothing Else…

I personally like to walk away from a discussion of pitfalls with a general rule of thumb: a failsafe way to avoid problems. In this case, here is my advice. Proof early and often using the same digital process for the proof as for the production run (which you cannot do with offset commercial printing but you can do with digital printing).

If you review proofs before proceeding, you will see whether your work-arounds have minimized banding, artifacts, and other problems. If it looks right on the proof, the final run should match exactly.

This entry was posted on Monday, November 30th, 2020 at 12:32 am and is filed under Design, Digital Printing. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.