In my post two weeks ago I covered designing a job that would be printed on a conventional litho press. Designing for digital is not much different. However, an understanding of how the digital press images is the key to achieving the results you are seeking. and avoiding any potential issues.
UNDERSTANDING HOW DIGITAL PRESSES WORK.
In my first post I suggested a quick read of my post about how litho and digital presses work. Basically, the digital press uses a dry toner (with the exception of the HP Indigo), which is electrostatically applied to the sheet of paper and then run through a roller that coats it with a fine layer of oil, which is then “fused” together under extreme heat and pressure. The heating process not only fuses the ink (or toner) to the sheet, but it also can affect the coating of the sheet (if you’re using a coated paper). Sheets that are not designed for the digital presses are susceptible to issues caused by the heating process required in the digital printing environment. Fortunately, many paper mills have created coatings that have been tested and certified for use on digital presses.
Many of the points I made two weeks ago are valid for either designing for litho print or digital print, but allow me to point out the few things that designers need to be aware of, IF they know they’re designing for digital.
WHAT TO WATCH OUT FOR
Here are the tips for designing for digital print:
- Gradients or vignettes: this is a tricky area, since some gradients are a PMS color, or just a CMYK mix, which have to be printed in CMYK anyway. But, if the gradient is black only, do NOT design it as CMYK. Digital presses and their RIPs have more success with a black gradient if it has NO cyan, magenta or yellow in it.
- Solids, or what digital press techs and operators call “flat fields”: as I mentioned, the process for images printing digitally is one created by electrostatically charging the print units which then transfer the image to the sheet. There are NO rollers, so there is no application of ink to the paper. Subsequently, large “solid” areas or flat fields can get streaky. Newer generations of digital presses such as the KODAK NexPress 3300 or the Xerox iGen 4, have taken great strides in finding solutions to printing good gradients, but it can still be a problem. The best way to prevent the issue is to have the flat field broken up by several smaller images, or reversed out copy in a large font size, or just keep the size to a minimum. It is most evident on solids that cover an entire page. Blues tend to be the most obvious.
- Solids along areas that score/fold: another issue caused by the digital print process is that the extreme heat causes the paper to lose moisture and become brittle, which will lead to cracking of the surface at a fold or crease. Many printers will score or run sheets through a creaser before they fold the sheet. For some digitally printed pieces, such as short run packages or folders, the die-score process is much more successful, since it presses the score into the sheet, rather than the score running along the sheet, which can lead to cracking.
- Saving images and graphics as RGB: in the first post I said save files in CMYK, but for some digital presses, the RIP sees the color gamut better and can reproduce color if the images are in RGB, and not CMYK. That’s not to say you cannot print images digitally that are saved over in CMYK. It’s just that the digital presses have capabilities with color that a litho press doesn’t have. Again, the best bet here is to check with your print services provider.
Designing for print has become much more sophisticated with the the explosive advent of the digital press. As printing goes more towards short run and direct mail – the sweet spot of the digital press – graphic designers owe it to themselves to learn the subtle differences in print design so they can navigate the waters as the business mode evolves.