Marketers who keep abreast of packaging advances and understand when to use them have a leg up in the battle for shelf supremacy. Unilever Foods is one marketer that understands this dynamic and reflects it in the conversion of its flagship 32-oz Hellmann’s mayonnaise jar from glass to PET.

Unilever Foods had converted its 48- and 64-oz jars of Hellmann’s mayonnaise from glass to PET, but resisted in the 32-oz size. “Converting to PET is more economical in the larger sizes because the resin weight-per-unit volume decreases as you go up in size,” explains Vinod Bansal, Group Manager, Packaging Technology, Unilever Foods.

Then, Unilever Foods discovered Amcor PET Packaging’s two-step blow-and-trim technology. The high-volume process forms threads as containers are made rather than during the preform stage. Amcor’s higher-volume approach made the conversion to PET financially practical for the 32-oz jar, Bansal says.

Blow-trim production saves resin, energy, and cycle time. It allows wide-mouth jar production from a standard narrow-neck preform, eliminating expensive injection-mold tooling. The wide-mouth finish is built into the bottle mold rather than the preform. Containers removed from the mold have two portions—the threaded finish and an upper dome that is trimmed off in an online process.

The 32-oz PET jar delivers the same product shelf life as a glass jar.