Designing for Digital Printing

With digital music on your iPod, and digital video on DVDs, it’s not surprising that the printing world is going digital also.  Unlike a Mozart Symphony that sounds very similar on your old cassette tapes and your MP3 player, designs reproduced on digital printing presses use very different technologies to create color and can look strikingly different from the same image reproduced on a lithographic press. These new digital technologies offer some exciting new opportunities, but they also have a few important limitations.

Four color not spot colors

The most basic piece of advice is: design using the four color process. All digital presses produce color using the four subtractive primaries (Cyan, Magenta, Yellow and Black); although a few can also offer individual colors at the same time.   Bright orange is just one color that is not simulated well using the four color process.

The technology used to create digital color can also affect the design choices. Digital presses do not use ink. They create color without the precise ability to control the flow of wet inks. Digital printing machines use dry toners to create your image. (One notable exception is the HP Indigo press which uses wet digital toners.)  The chemical difference between the wet trapping of ink and the application of dry power toners results in significant differences in the reproduction of color. This modifies the color gamut that can be reproduced. 

Color matching systems that offer you a specific mix of inks to make a single spot color don’t translate well onto digital presses.  So forget the old notion that printing in black and one spot color is less expensive than printing in four color.  These presses use these four colors, so go ahead and use all of them.

It would be best to ask your supplier to review your design before trying to reproduce a large solid color area. Some streaking can occur on digital presses and this is most apparent in solid coverage areas. Often a screened background will look best on a digitally printed piece if the color gradually changes. An example of this could be a panel with a screen build that gradually changes from pale Robbins Egg Blue to a darker Sky Blue across a screened area.  Because digital presses do not use the same process to lay down a solid of a color as wet trapping inks, it’s best to vary them. At the same time, digital presses are less likely to have difficulty with inline ink depletion that can cause “ghosting” in a dark spot color on a lithographic press.

Another tip for screens is to be sure that black type surprints and is not “knocked out” of a background screen (a knockout is often the default for any type printed in a screened area).  Surprinting black type can eliminate the “halo” effect of mis- registration.

Good quality but not for every design.

Digital reproductions get better and better with each new generation of presses. The faithful reproduction of flesh tones, reproduction of colors in shadow and in bright highlights have improved considerably. However, there are still significant limitations, including the lack of specialty inks (including metallic or Day-Glo inks). No varnish techniques are available on digital presses as yet. 

A selection of papers but not every paper in the sample book

Digital presses allow you to choose among white offset, matte and coated paper, but not every weight and thickness.  Most can not run light weight coated papers (70# text is often the lightest) or heavy coated board stock (100# Cover is often the maximum).  It wouldn’t make sense to use a colored paper on a digital press because the CYMK colors will change with the color of the paper, so don’t select canary yellow bond.  Toners will not adhere to all finishes and do not fill in uneven surfaces, so a pebble finish would not make sense on these presses. Here again, there are some significant differences between the papers and substrates that are acceptable on specific digital presses, so be sure to check with your supplier for the options they can make available.

Personalization – many more options

The use of personalization is another feature where digital presses afford new options based on this new technology.  Personalization is not limited to one area of the printed piece, as is often the case with ink jet addressing of a mail piece.  The personalization can be used on both the front and back of the piece.  Laser personalization is often limited to one side of the paper. Go ahead and put personalization anywhere it will support the design.  The personalization can include pictures and the text can be reproduced in color, Personalization is available on the entire image area of the piece.

 Think differently and use the features technology has to offer

Although digital printing has made full color reproduction more affordable, especially in smaller quantities, the digital presses do not offer the variety that the best lithographic presses afford.  At the same time, digital reproduction can facilitate some designs that are incredibly difficult to accomplish in any other way. No other printing equipment will allow you to economically design a piece that has a photographic image in four color that changes with the variable text. With digital printing, you can change the picture of a unique product for each individual that receives the mail piece.

The best advice is simply put: If you are designing for digital print production, don’t think in terms of printing with single inks.  Design your image as if it were to be produced on a CRT or television screen (but remember to convert your images from RGB to CYMK before transmitting your final files). Don’t limit the variable nature of the piece.  Change the person’s name in black if you want, but change the background and the images on each individual piece as well.  This way, you will get the most for your digital printing dollar.

For more information on designing for digital printing and the digital printing process, you can obtain a copy of “The Very Latest Designer’s Guide to Digital, On Demand and Variable Color Printing” by David Clark and Frank Romano from GATF Press at www. gatf.org.

Some of the common pitfalls of digital and variable printing causing customers to reject jobs are listed in this book, including:

“Image resolution is too low, resulting in “pixilated” output.

 The paper stock chosen for the job performs poorly on a digital press… Make sure any substrates you use are certified for use in a digital press.

-Large areas of solid or screened color can exhibit variation in toner coverage and screened tints may show blotchy areas.”