Up, Up, and Away

As an example, he mentions the issue of stress whitening that can occur in retort applications due to the variability in expansion rates of adhesives and film layers. Frost says that Sonoco works closely with its ink and adhesive suppliers to eliminate such problems.

Pellingra also notes that inks, adhesives, and sealants need to be specially formulated to survive retort conditions. “In addition, process conditions and quality-control testing on the printing press for ink adhesion, the laminator for adhesion bond strengths, and the pouch machine for seal strengths are held to very stringent parameters, much more than products going into other more common food applications,” he says.