PRINTING: PROTECTING YOUR BRAND
One of the main reasons feed and seed producers are moving from paper to polywoven packaging is their appeal in the retail environment. Functionally, polywoven or BOPP/WPP bags are stronger and more durable than paper, enough reason to switch. But they also print beautifully to be much more inviting to the eye of the consumer. With that added brilliance comes an additional challenge: your bag supplier must have expertise in printing to ensure the quality of the print job fulfills the capability of the BOPP bag.
BOPP bags are printed on either flexographic or rotogravure presses. These printing systems demand specific attention to key issues to ensure your bags are printing properly and consistently from the first bag to the last, and through multiple reorders employing the same artwork. There are some key steps to ensuring you and your supplier work together to produce a perfectly printed bag:
Whether you design in-house or outsource to a third party, the design has to accommodate the construction of the bag. Your graphics will travel through rotary and linear processing, so it’s important your supplier can help your design team layout the artwork so the finished bag meets your expectations. Some things as simple as where the lap-seam meets on the back panel, or how color breaks accommodate bag length and how it will be sewn, or where critical information is located. Make sure your supplier can help in the critique of the important mechanical aspects of artwork and is capable of recognizing in advance where adjustments to the artwork need to be made to accommodate the way the bag moves through construction.
Color is brand. Protecting your brand requires hitting the color target and staying on target throughout the life of the product and production schedule. The key to getting and keeping color accurate is the formulation for the ink mixing. The color should be validated by a densitometer, which measures color saturation, both in the ink room and on press. The appropriate test to ensure the right color and consistency is an Lab (L, a, b, color space) to determine color and color differences. These are systematic and verifiable methods for delivering results that your supplier should be well-versed in and prepared to deliver on.
Key to controlling color throughout the printing process is maintaining ink viscosity. Too low, and fine details are washed out; too high, and halftone dots tend to disappear. Your bag supplier should be able to demonstrate an understanding of the difference between digital color control in the ink room and on press, and be able to explain how they are going to control your color and hence your brand.
For flexographic or gravure printing, we recommend your artwork is produced with a resolution of 133 to 175 dpi (dots per inch). More importantly, confirm that your printer’s resolution capabilities can meet your designer’s expectations. Your supplier should be capable of producing color separations for gravure cylinders or flexography plates that ensure sharp and clear images and copy throughout the print run.
In the process of building your BOPP/WPP bags, printing is most important to controlling your brand, not just in a single bag run, but over the life of your order entry process. Make sure your supplier understands how your artwork lays into the bag making process and can control color and resolution quality throughout to ensure you get what you expect in every bag.