Duct Tape is designed to work on metal ducts, is used frequently by the space program and was originally designed to be used on ammunition cases for the military. As seen here, it fails terribly on cardboard. This box is a return drop off and as it was waiting to be staged, the duct tape, with the help of gravity, fell right off. (We quickly remedied the issue.) You can expect similar results when using masking tape, painters tape, scotch tape etc.. Shipping tape is the only reliable choice to ensure you packages, their contents and their labels arrive as intended on the receiving end. We sell rolls and tape guns for your next round of online shopping/drop off needs.