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Shipping Boxes Wholesale Blog

ECT vs Mullen

Posted August 15, 2014

There is always a lot of discussion in our industry regarding the strength of a corrugated carton or sheet.  You have your basics, single wall, double wall, or even triple wall.  You can also get into the different flutes sizes which range from an A flute to an F flute and you can even get into the different liner board combinations depending on your specific project.  But one of the most common conversations when talking about corrugated strength is the testing method.  
There are two different test that measure the strength of corrugated.  The Edge Crush Test and the Mullen Bursting Test.  A piece of corrugated, whether it be a standard box, corrugated sheet, or a completely custom creation is always tested by either of these two tests.  There are people who believe that one is always better than the other.  There are also people that believe these test are  equivalents and easily interchangeable.  Neither of these statements are entirely true or false.
Lets talk about what these two tests are and how they are different.  The Edge Crust Test, commonly referred to ECT, measures the stacking strength of the item.  The Mullen Bursting Test measures the force required to puncture or rupture the face of the corrugated.  The first fundamental difference is the Mullen Bursting Test has a required minimum for the board basis weight.   The Edge Crush Test is eliminated this requirement allowing the use of different recipes to make each type of corrugated as long as it meets the Edge Crust Test standards.  These different recipes allow for the use of lighter weight materials while still providing high performance.  The ECT cartons are sometimes referred to as lightweight cartons, which is pretty true as they typically weight less than an equivalent Burst Test rated item. 
For example compare a 275# single wall to an equivalent 44 ECT single wall corrugated board. On average, the 275# Burst Test rated single wall carton will weigh 175 pounds per 1000 square feet of material used. An equivalent 44 ECT rated single wall carton will weigh on average 149 pounds per 1000 square feet of material used. The 44 ECT board will reduce the material used by 14.8%." - State of Oregon Department of Environmental Quality.
These two tests measure different aspects of corrugated so it is hard to say that one is always better than the other.   Some believe that comparing these two items are always equivalents but I believe you cannot consider these to be equivalents but rather alternatives.    It will always come down to each individual project and the best option for you. If you need help deciding which will work for your needs, please contact us at customerservice@conpacgroup.com or 877-496-CONPAC (2667)