5 Misconceptions About the Humble Corrugated Box

It’s likely that every day, your company packs products into corrugated boxes to keep them safe in transit. You’ve done if for years. So, is it possible you’re using the wrong box? Absolutely. There are a lot of basic elements that go into a box’s design and using the wrong one can be a costly mistake that a lot of companies make. Here are the most common misconceptions we’ve seen people make about corrugated boxes.


1. First, they aren't cardboard boxes

Whenever someone calls a corrugated box “cardboard” it’s a big red flag that they’re a rookie. Corrugated refers to a box with an inside and outside liner with zig-zag fluting between the two. A cardboard box is like your cereal box, it’s just made of thick paper. Is corrugated made with cardboard? Yes, but it doesn’t matter. Cardboard means paperboard (the packaging your cereal box comes in) and corrugated means boxes with fluting.


2. A 200 LB. bursting strength box isn’t (totally) super duty

Ever notice the little certificate that is stamped on all your corrugated boxes? That’s a box maker’s certificate, and it gives a lot of details about how the box was made and its strength. It either has an Edge Crush Test (ECT) measurement (usually 32, 40, or 44 LBS) or a Bursting Test measurement (200, 275, or 500 LBS).


If you want a strong box, go with the highest number, right? Nope. The burst strength and ECT measure two totally different types of strength. Burst strength measures how much pressure one square inch of the box’s wall can take before an object bursts through it. ECT measures the strength of the box’s walls and how many pounds per square inch can be stacked on it before it crushes. In general, if your boxes are sent on a pallet, you need to consider ECT strength.


We talked with Zach Deering, Rocket Industrial’s Packaging & Performance Engineer that works with clients to test and select corrugated boxes. He gave us a great real-word example of why often ECT matters more than the bursting test. “A client I worked with wanted one box that would fit most of their products, so they stocked a huge 200 LB burst strength box. But it’s a big box, so a lot of the time it ended up having a lot of void after packaging. They came to us for help because these boxes were getting destroyed on pallets. We ran a bunch of tests to figure out which box would be better and ended up recommending a 44 ECT box instead. It could hold most of their products and stay intact even with a big empty void.”


In palletizing, the concern isn’t about boxes bursting, it’s about crushing. “There’s confusion since people think 200 LBS is stronger and therefor the best, but often 32 ECT is the right choice. And at about 20% less than the cost of a similar 200 LB box, it’s the economical choice too,” says Zach.


3. Even for heavy packages, you don’t always need the highest ECT you can find

So your boxes are going to be stacked on a pallet, and you want to make sure you get the right ECT strength. How do you decide? For our clients, we start by thinking about how they’ll palletize. What is the most weight a box on the bottom of their pallet will see? Are there any extreme environmental or distribution conditions to consider? We run a static compression test of their current box based on ISTA standards and Fibre Box Association environmental factors. The tests, basically, replicate the environmental conditions and put weights on a sample box and analyze the results.


For example, one of our clients had a 32 ECT box and was considering upgrading to a 40 ECT box and wanted to know whether it was worth the cost. Our engineers tested the client’s current 32 ECT, another manufacturer’s 32 ECT box, a 40 ECT, and 44 ECT box to see which one would hold up best. We recreated their pallet at a “worst case scenario” where a box on the very bottom of the stack had 560 lbs. of weight on it. How would the boxes hold up? After 1 hour, would the box fail or have significant deflection (which is a change in the box’s shape due to pressure)?


“The tests prove which box strength is the right choice and gives us a good indicator of what ECT rating a customer should be using. If the 32 ECT box fails within the first hour, then it would be best we go up to 40 ECT,” said Zach. After testing, it ended up that the customer was indeed using the correct box. “The 32 ECT held up really well. Without testing, the customer would have chosen a 44 ECT box, which costs 15-30% more, and never have realized they didn’t need a box that strong.”


4. There are a lot more corrugated box options than you think

We hate to make things more confusing, but there’s another component to corrugated boxes that we haven’t mentioned yet. It’s paper thickness, which is classified as single, double, or triple wall.


“In order to make ordering boxes as quick and easy as possible, resellers pitch the idea that there’s one option that’s super strong and expensive and another that’s lightweight and cheap, but there’s a lot more to it than that,” says Zach.


If you must pick just one or two SKUs for a box, you have to consider your palletizing conditions, storage time and the climate the box will be in. For example, a box shipping from Wisconsin to California in February is going to hit sub-zero temps, snow, heat, and humidity. These things aren’t called out by just one number printed on a box. If you have a big heavy package to ship, it might be time to upgrade from 32 ECT to a 48 ECT double-wall.


Most box manufacturers run a handful of standard board liners, and something like a 48 ECT double-wall would be a special order, which means it’s more expensive or needs a higher minimum order. But don’t let that dissuade you from getting it. Rocket Industrial will work with you to get a special order. To keep cost down, we recommend special ordering in bulk but keeping the extra at our facility. We will ship out inventory as you need it.


Find out more about our warehousing and inventory programs


5. Getting your corrugated boxes tested isn’t a big hassle, it’s actually a free service we provide

We’re one of the only companies that has a packing testing facility that will test manufacturers against each other to find the right corrugated box for your needs. Because, yeah, different manufacturers with the same specs will have boxes that perform differently. Take for example a recycled corrugated box. It scores high on moral and ethical points, but will it hold up as well in humid conditions as a non-recycled box? Can you use regular tape, or will you need tape specially designed for recycled boxes? Let’s find out. Tell us the worst-case scenario of the climate you’re shipping in, give us the details on your palletizing conditions, and let us know the maximum storage time of the product in its shipping container. We’ll put your box through testing and either verify you’ve made the right choice or recommend a different box. Best of all? This service is totally FREE for Rocket Industrial’s customers.



Packlytics Packaging Test Lab