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
9 comments
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August 27, 2010 at 6:52 am
Chris
Nani -
How did you know flexo was the best option for this project? Was it suggested by a vendor?
Just curious.
Thanks!
August 27, 2010 at 7:18 am
naniprints
Hi Chris, Thank you for your question. My client first needed a a couple hundred with a 4-day turnaround, so I contacted my rep at a digital print house that specializes in unusual products. Later when I asked him to price a longer run, he recommended that I also price them with a flexographic printer. They would be much cheaper he said, and added that that’s how true clings were made. The “cling” material used in digital is not a true cling, it is a stiffer plastic coated with a light repositionable adhesive, while the plastic roll cling material is more like very heavy food plastic wrap (picture how it “clings”) that is purported to stick longer. Digital inks also fade faster unless they are using UV digital inks, which yielded the highest price.
So I got prices from two digital shops (one that did UV digital inks) and the flexo shop he suggested. The price difference for 2,500 was dramatic, about 60% less for flexo. (Disclaimer: This may not always be true; your results may vary, depending on your artwork requirements.) Less expensive, longer performance, vibrant color: all these factors made flexographic printing a good choice in this case! (I also read that the process is also well suited to printing on flexible materials and there are flexo presses that can print on 3-d products such as bottles.) ~Nani
August 27, 2010 at 9:36 am
Anza Evans
Nani…What a great article! Flexo is so interesting. I used it a lot when doing labels that needed to come in rolls for food packaging. Also used it for some beer cartons (corrugated). They were challenging because the ink fits vary so much in the print process.
August 27, 2010 at 9:51 am
naniprints
Hi Anza, Thanks for your comments. I’ve probably ordered flexo products in the form of labels on a roll and not even realized it! Yes, very interesting processs…I can see how registration could be a problem. ~Nani
December 26, 2012 at 3:02 am
rahul
why ink spreads during printing on polythrne rolls on flexographic printing machine?
As a result the printed design doesnt looks good.
Plz tell how toovercome this problem.
December 26, 2012 at 8:55 am
naniprints
I have printed with this process only once and do not know the answer to your question. Perhaps a reader will comment with some suggestions. -Nani
March 30, 2013 at 9:01 pm
naniprints
I have no idea.
August 27, 2010 at 12:15 pm
John Vinoski
Nani – Nice article, with some very good points. Flexo printing is everywhere, but is not well known. I have seen estimates that 90% of the product packaging in the average grocery store is printed flexographically. As a flexo prepress company, we spend a lot of our time adapting artwork to print well via the flexo process. Designers will occasionally contact us prior to starting a project, asking for help to get it right, but more often, we spend time retooling a file for flexo printing. Your point about working closely with the flexo printer is absolutely critical. The flexo printer or a flexo prepress house can save you a lot of time and money (and probably wasted packaging material) by helping you (the designer) build your files in the best possible way to achieve the optimum print results.
While you describe flexo plates as “giant rubber stamps” (and that is how I usually describe them as well!), you should know that flexo printing is producing beautiful print results on a huge variety of materials for packaging – films, foils, shrink sleeve materials, folding carton board, and much more. We are printing at 175 line and above, getting great detail and fantastic color. Flexo is a great process, and I have seen it come a very long way in the 30 years that I have been doing it.
Thanks for the great article about flexo! Love your site!
John Vinoski
August 27, 2010 at 12:28 pm
naniprints
Hello John, Thanks for stopping by and adding to the information on flexographic printers folks may be looking for when they land here at Printing Disasters—and How to Avoid Them. Finding a guide who is passionate about his print craft as you appear to be is the secret to achieving the design results designers and print managers are aiming for! I’m glad you enjoyed the blog; please visit again! ~Nani