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Corrugated Basics: Mullen Test VS. ECT

Making the Grade

Understanding the difference between the two types of board grades helps when selecting the right packaging to ship your product safely and with confidence. Information regarding a packaging board grade is typically found on the Box Maker’s Certificate (BMC) printed on the bottom of most boxes. The BMC contains a number indicating the strength of the liner board, along with Edge Crush Test (ECT) or Mullen Burst Test. Knowing whether the board is ECT or Mullen Test indicates where the board’s strength is, and its primary function.

Edge Crush Test (ECT)

ECT is the newer board grade, created in 1991. This board grade focuses on the strength in the vertical fluting of the linerboard. The vertical fluting is a key component in determining the edgewise compression/stacking strength. This helps to achieve the best fundamental stacking performance of corrugated packaging.

Mullen Test

The Mullen Test is the original standard used before the creation of ECT and has been in use since 1919. This test is used to measure the bursting strength of the linerboard. The Fibre Box Association Handbook defines bursting strength as the strength of a material in pounds per square inch as measured by the Mullen Tester. The Mullen Test focuses on the grade of the linerboard, versus the vertical fluting, in the ECT.  This is to measure and help prevent external or internal forces at intense pressure points. Due to the need for use of higher-grade linerboard, the Mullen Test can be slightly more costly than ECT.

How to Know What to Use

The first step in knowing which board grade is best for you is by simply understanding that there are two tests available. The second is to ask questions, collaborating with a packaging professional to design the best box to carry and protect your valued product (s).

Test ECT at Home

Here is a fun activity you can do at home to help you further understand ECT stacking strength. All you will need is a box, preferably a Regular Slotted Carton (RSC), with a BMC identifying the board grade. With the box empty, close the flaps and secure with a piece of packing tape. Place each foot over adjacent corners of the box and stand on the box. If done correctly, the box should not crumble. This is a great demonstration of just how much weight the very bottom box in a stack might have on it when a unit of product is being shipped, and how reliable your packaging is.



Questions, or to get started with your box design, we are ready to help!

And if you tried the at home experiment, we’d love to see!  Share photos on social using the hashtag #RPECTTest.

About Rusken: Rusken is a dynamic, modern integrated packaging company with locations throughout the Southeast United States. With fourteen (14) facilities in seven (7) states, Rusken is a forward-looking regional organization. Headquartered in Cullman, Alabama, Rusken has experienced exponential growth over the last decade. This success is driven by an entrepreneurial spirit, focus on family-based values and a commitment to a truly remarkable customer experience. From standard corrugated boxes to highly customized packaging solutions that require robust design-work, colorful printing and hand finishing, the good people behind the Rusken name are passionate about quality, delivery and customer smiles.