What an Illinois winter does to corrugated

February 2024 in northern Illinois was rough. Three separate stretches of single-digit highs, two of which dropped below zero overnight. Our yard's heated bays held up fine, but the inbound loads told a story about what cold does to a corrugated supply chain.

Cold itself is mostly okay

A frozen corrugated panel doesn't lose strength. The fibers are stable at low temperatures and the adhesives we encounter in modern double-wall and triple-wall constructions don't crack at any temperature we see in the Midwest. Cold boxes are perfectly serviceable cold boxes.

The thaw is the problem

When a cold box hits a warm warehouse, two things happen. First, condensation forms on the surface — sometimes inside the box, sometimes outside, sometimes both. Second, the condensation soaks into the fiber and the panel temporarily loses 15–30% of its strength while it dries out.

For our purposes, that means we have to be careful about grading boxes in the first 36 hours after they arrive from a cold trailer. The strength reading at the bench is artificially low. We re-grade boxes that look borderline a day or two after they've equalized. Some come up a grade. Some don't.

What this means for buyers

If you receive a cold load in winter, don't immediately stack three-high in a warm warehouse. Let the boxes equalize for at least a day before applying full stack loads. The fastest way to crush a perfectly good gaylord in February is to fill it up and stack it up the same day it came off a cold trailer.

Our grading bench learned this the hard way in 2017. We've been writing about it on internal training material ever since, and apparently it bears repeating in February 2024.