Light the torches and sharpen the pitchforks; the man who made bags of potato chips so darned difficult to open has confessed his wicked crimes. Engineer John Spevacek made the bizarre admission this week, 'fessing up to being "that guy" who decided bags of chips should be sealed more strongly after complaints that the bags had been popping when shifted from high to low pressure in transit.
"I was in the Packaging Films Group, making multilayer polypropylene films for food packaging. The film had a heat-seal adhesive on one side of the polypropylene base. One of our larger clients used our films to make potato chip bags. The problem they had with our existing films was that the they seal was too weak. The client's chip-making plants were located west of the Rocky Mountains, so when trucks would drive their chips out to California, some of the seals would open up due to the pressure difference between the high altitude air and the air sealed inside the bag. And so they needed a stronger seal from us, which was then passed down to me" John Spevacek
Spevacek apparently had three options for how to handle the issue: either increasing the time the heat seal process was applied for, increasing the temperature of that process, or increasing the pressure at which the sides of the bag are clamped together. He opted for pressure - slowing the production line down, either literally or by having to wait for bags to cool from higher temperatures, not being a preferred option for potato chip businesses - and hence the sometimes tricky to pull-apart packaging.
"The best option was to develop an adhesive that sealed at a lower temperature," Spevacek concludes, "something that was successfully accomplished, or so I'm led to believe from all the complaints that colleagues pile on me now that they know I'm that guy."
The bagging machines themselves are enticingly complex - if, that is, you're one of the people fascinated by "how things work" style insights into factory production. Multiple individually-weighing scoops are automatically and independently controlled to dump just the right amount of product into the bags, in a process that's mesmerizing as the video below shows.