Another Printing Disasters—and How to Avoid Them story…

Flexo printed window cling for Swedish Ballard

I just completed this window cling project for Worker Bees, a Seattle agency. I had the clings printed on a flexographic press.

Although I am an old hand at managing offset and digital print projects, this was my first flexographic printing experience.

In this article I’ll describe a few of the things I learned during the course of this project.

My flexographic adventure

A flexographic press is a type of rotary web press, so the plastic cling material for my job—backed with white paper—came on a roll.

Flexographic printing is a direct printing method, not an offset method. The black printing plate looked like a giant rubber stamp, and the image on the plate was backwards. The plate was wrapped around a cylinder about 15 inches long. The yellow background was a flood coat that didn’t require a plate.

The last cylinder in line on the press was tooled with a round-cornered die so that the clings came off the press already cut to finished size and shape. This press had a UV coating and drying unit to protect the printed image from scratching off.

These flexographic inks were not quite opaque, but the ink body was thicker and more translucent than offset inks. In order for my design’s yellow background to show up well in a window, the final color was back-printed with white ink. This meant that what I had thought was a two-color job was actually a three-color job. The UV coating was not counted as an ink in the printer’s price calculations.

The sticky side of the cling material is what’s on bottom while the job is printing, and it’s also the side the design will be viewed from. In other words, the back of the material is printed, so that you view the art through the clear plastic. This translates to an ink order of black, then yellow, then white, then UV coating.

Disaster Avoidance Tips

  • If you’ve read other articles on the Printing Disasters blog, you’ll know I always recommend working closely with your printer. But when the process is one you don’t know well, this is an especially important step toward ensuring a successful outcome! The earlier you can involve the printer, the better.
  • Be sure to show the printer your preliminary artwork when you request the pricing so he can alert you to any printing problems in your design. (My window cling art originally contained a blue logo with fine detail. It was too fine to trap, so  my printer recommended that a black ink version of the logo be substituted for the blue.)
  • Pre-thinking the order that the inks will go onto the substrate is a necessary part of planning for flexographic printing. In this case, the black ink was correctly set to “overprint,” but it actually printed before the yellow did. (Does your brain hurt yet? Mine did!)
  • The dies for flexographic printing (called the tooling) are much more expensive than the ones used for offset printing because they must be tooled onto the rounded metal cylinder. For this reason, it’s best to use an existing die size when possible. The cost to make new die for my project would have been $500 to $600!
  • Ask the printer to suggest suitable existing dies for your project before finalizing your design and seeking client approval!

Do you have experience with flexographic printing? If so, please share your tips by leaving a comment. (Click “comments” at the top of the story.)

© 2010 Nani Paape