Flexible Barrier Packaging Printing – Best PracticesElizabeth
Flexible Barrier Packaging Printing – Best Practices
This document is designed to answer some of the most basic question regarding the best practices when printing of flexible plastics. These considerations apply to:
- Mylar bag printing
- OPP printed materials
- All common substrates with standard dynes.
- All plate and cylindrical prints, both trapped and reversed.
Since many designers and teams are not familiar with the specific technical specifications associated with flexible barrier packaging printing and plastic printing, this document is designed to help give you a brief overview for your project.
Design Consideration: Raster vs. Vectorized Art
Flexible barrier plastics do not accept ink like papers do, thus your graphics type is critically important. Each file type has strengths and weaknesses.
- Pixel/Raster artwork is best used for photographs.
- Vector art is best for type, distinct graphics, and gradient. See examples below.
Please watch for Line Art/Vector files that have Pixel/Raster images embedded or linked in them. These images can be high OR low resolution. The links can be missing, leaving only a screen FPO.
Design Consideration: Resolution vs. Line Screen
Customers often ask about resolution, but resolution is only one part of the process.
Resolution: is a function of how the artwork is created and saved. Resolution applies to raster elements (i.e. photographs)
Line screen: is a function of the technical capabilities of the printing process. Line screen will apply to all elements of the design. Line Screen is a limiting factor for which process is appropriate for which project.
How high of resolution should you aim for when working with photographic elements? Higher resolution will always print better than low resolution. 300 dpi is a minimum you should aim for.
CYMK vs. Spot Colors
A common issue is re-purposing artwork that a customer has successfully printed as CMYK on paper. It will need to be converted to Spot Color on plate printed projects. The reason CMYK is not a proper choice for all elements when printing flexible plastics is because of the differences in printing technology between paper printing (as for labels) and flexible packaging printing, like printing stand up pouches, or lay flat bags.
Also, customers are not aware of changes made to their art by previous printers. Items like colored type and line graphics will always print better with Spot Color than CMYK Process because a single pigmented ink is used as opposed to several process plates.
Best use of Spot Color
- Logos and type: Especially small type.
- Vectorized illustration: Most not-photo elements.
- Backing plates: White plates to increase opaqueness of clear base material
- PMS call outs: By definition a PMS color is spot
Best Use of CYMK
- Plate count limits
- Some screens
Trapping will be required of all complex artwork where plates of different colors touch each other. Trapping should not be done by the customer because each printing process and each printing press will have unique settings. Reversed out text will always print best with a solid outline when more than one printing plate is involved in the design.
How a gradient is designed can have a drastic affect the final printed appearance. A gradient on a computer monitor or inkjet print can be much smoother and more vibrant than ink dots on flexible packaging. Pastel gradients will always print best if converted to Spot Colors.
- CMYK gradient with all 4 plates can print grainy
- CMYK gradient with under 15% coverage will drop to 0%
- CMYK gradient reduced to 2 plates will print much smoother
- Spot Color Gradient with 100% coverage base overprinted with spot color gradient.
Multiple White Plates
Even on digital projects, sometimes a plate or two plates of white ink are required to increase opaqueness and color vibrancy. This is because clear base film printed with a design, especially one incorporating a product window, will have better opacity and color fidelity if one or two White Ink plates are used in a double hit configuration. There will be a marked reduction in the amount of color interference from the design coming through from the BACK of the bag OR from the product in the Bag.
We hope these considerations have helped you understand some of the basic technical best practices that lend a hand in ensuring great printed flexible packaging results! There are many other technical aspects to plastics printing, and we will help guide you through the process.
We always provide technical art setup as part of our pre-press process.
When you apply the preceding considerations to your project you will help ensure that your packaging looks its best. Additionally, many of these considerations are also requirements of major retailers and distributors such as Wal-Mart and Trader Joe’s.