The ECT Test measures the top to bottom compression strength. These tests how strong the box will be when stacking other objects on top. The test measures how much weight can be applied before the box edge crushes.
On the other hand, a Mullen (or burst) test measures how much pressure the corrugated board that makes up the box can handle before it ruptures, or bursts. The Mullen test indicates how much load carrying capacity the board can handle.
Every box that has been tested either ECT or Mullen will have a stamp, normally on the bottom.
When shipping Parcel Carrier such as UPS, you must adhere to their guidelines before any claims can be made:
|BOX STREGNTH UPS GUIDELINES 32 ECT Single Wall 65 lbs 30 lbs 200# Single Wall 65 lbs 40 lbs 275# Single Wall 95 lbs 65 lbs 350# Single Wall 120 lbs 80 lbs 200# Double Wall 80 lbs 60 lbs 275# Double Wall 100 lbs 80 lbs 350# Double Wall 120 lbs 100 lbs|