Plastic has traditionally been recognized for its functional capabilities. It is strong, resilient and at least semi-impermeable, making it a sensible choice for packaging perishable or environmentally sensitive liquids like milk, detergent and other cleaning agents.

However, over the last five years plastic has steadily gained favor for its aesthetic properties, and is now recognized as a clear winner in the competition for shelf appeal. Plastic packaging is available in a variety of elegant finishes and effects that allow the beauty of your product to show through. Clear, lined and frosted versions can be matched to almost any color for maximum brand exposure and custom product design.

Additionally, plastic converters have mastered techniques once reserved for paperboard, such as printing on plastic, spot coating, foil stamping and embossing, making plastic as attractive as it is functional.

It is this unique combination of beauty and durability that makes plastic ideal for versatile product packaging and point-of-purchase (POP) displays.

Although plastic is growing in popularity, paperboard still predominates on the retail shelf. Choosing plastic packaging is an excellent way to differentiate your company and your product in a crowded retail environment.

Given the wide variety of plastic substrates available today, including PVC, APET, PET, PETG, polyethylene, and polypropylene, it is helpful to compare material performance characteristics with project specifications in order to select the best plastic for your application.

Polyvinylchloride (PVC) is one of the most popular plastic substrates used for carton converting. PVC, commonly referred to as "vinyl", is available in either flexible or rigid form, with material thickness from .007 to .020 gauge. Rigid PVC folding cartons combine maximum visibility with package integrity. The enclosed product is held securely and is viewable from every angle for dramatic shelf impact.

Custom finishing techniques such as radio frequency (RF) scoring create rounder, softer box edges that add a unique look and feel to any package. Brand logos and other graphics can be added by offset printing either custom colors or standard 4-color process inks.

Box grade PVC is economical, RF seal-able, and has a high impact modifier that resists cracking to temperatures of -31 degrees Fahrenheit. It is, however, slightly more brittle than some of the other plastic substrates, so it may not be the best choice for a package that will be subject to excessive manipulation during finishing or in the retail setting.

Although each plastic substrate exhibits unique performance characteristics, there are some universal principles to consider when printing on plastics:

1. Plastic doesn't absorb water. Excessive use of fountain solution on any substrate, but especially plastic, slows ink oxidation and impairs adhesion. For optimum performance inks that are specifically formulated for printing on plastic should be used. These inks are designed to perform with minimal water, allowing the printer to reduce the amount of fountain chemistry and improve adhesion. Furthermore, printing with UV inks allows for greater latitude than printing with conventional inks. Since UV inks are cured rather than oxidized, drying is less of an issue.

2. Dyne level variations are greater with plastic than with paper. Ink bonds to the substrate by surface-tension potential, or dyne level. Optimum dyne level is 40. If the dyne level is too low (below 38) it will be difficult for the ink to dry and it is likely to rub off, whereas a dyne level that is too high (above 50) will create significant static. For optimum results, a sample of the plastic substrate should be measured for its dyne level and then matched to a suitable ink.

3. Plastic tends to accumulate static. When printing on plastic it is especially important to use an anti-static device on the press and to regulate pressroom temperature and humidity.

Plastic has added a whole new dimension to packaging, turning the ordinary into the extraordinary. As you can see, however, choosing a substrate is more complex than simply asking "paper or plastic?" Choosing a folding carton supplier with experience and expertise in converting plastic is just as important to the decision making process.

In the next newsletter we'll explore APET, another popular plastic substrate. In the meantime, consider the advantages of plastic for your next package design.