Why Box Bottoms Suddenly Fail

It is entirely possible to make a box with very sturdy walls and still have it fail at the bottom. As soon as the lower flaps open, the contents do not care how strong the sides are; they fall to the floor anyway. Most bottom failures begin before you even start packing anything into the box. Therefore, taking a little time to learn the proper way to construct and seal a cardboard box can prevent a great deal of trouble and expense.

Place the flat box on a clean surface and open it to form a square. Inspect the side seam where the box was joined by the manufacturer. If there are any signs of looseness, splitting, or severe bending around the seam, choose another box. Press each corner firmly into position without applying excessive force. A box that leans to one side will place uneven stress on the bottom once it is fully loaded.

Fold both short flaps inward toward the center before folding the two longer flaps over them. The longer flaps should meet in the center without leaving a large gap. Avoid weaving the flaps over and under one another. Although this method may provide temporary support for an empty box, it can bend the cardboard at the base and create an uneven surface when products are loaded inside.

The type of tape used must be suitable for the weight of the package and its intended shipping route. Tape that is adequate for lightweight items, such as shirts, may not properly secure a box containing heavy metal products. Cold storage, dust, moisture, and dirty surfaces can also prevent certain types of tape from adhering correctly. Tape should always be applied to clean, dry cardboard. Run each strip along the full length of the seam and press it firmly against the board to ensure proper adhesion.

A single strip of tape placed across the center seam may be sufficient for very lightweight shipments. However, most packages require additional strips of tape along both side seams to provide greater stability. When applied in this manner, the strips should extend beyond the seams and continue slightly up the sides of the box. Tape that ends exactly at the edge of a seam may begin to peel when the carton is lifted.

Weight distribution inside the box can also affect the strength of its bottom. A single heavy item positioned near a corner can place excessive pressure on that area. Distribute the load as evenly as possible and consider using inserts, dividers, or firm cushioning pads to spread the concentrated weight of smaller products. Sharp or pointed objects should never rest directly against unprotected cardboard because they may puncture through the bottom during handling or transit.

After packing the order, lift the box several inches above the packing table. Listen for sounds that may indicate the tape is pulling away, and check whether any of the bottom flaps are moving or opening. Place the package back on the table immediately if the bottom begins to sag. Repacking one order is far less difficult and expensive than replacing damaged products or cleaning up items that have fallen onto the floor.

Cardboard boxes that are properly assembled, sealed, and packed will distribute their loads more evenly across the base. This provides greater protection for the contents and gives packers confidence from the first lift through the final delivery.