Cardboard boxes need to be assembled and closed tightly when shipping items so the contents do not spill out of the box while in transportation. Strapping tape and packaging tape may become loose or tear off a package from being loaded and unloaded on delivery trucks. Gluing cardboard boxes closed provides security in shipping that will not release its hold and allows gifts to arrive securely.
Turn the box upside down on a table lined with newspaper. Fold the left and right bottom flaps inward on the box. Fold the top and bottom flaps down on top of the side flaps. Mark a pencil line along the top and bottom flap edges where they meet the side flaps.
Plug a hot glue gun into an electrical socket and let it warm up. Most glue guns have a light that illuminates when they are ready.
Insert a glue stick into the rear of the glue gun. Press the stick firmly into the gun as far as it will go.
Open the top and bottom flaps. Place the tip of the hot glue gun on the left flap. Squeeze the trigger and apply hot glue to the flap in up-and-down rows ending at the line marked on the flap in Step 1. Repeat this procedure to apply glue to the right flap. Fold the top and bottom flaps down and press down carefully with your fingers away from the flap edge to let the glue adhere. Hold the top and bottom flaps in place for about a minute.
Turn the box over and place the contents to be mailed inside.
Repeat Step 4 to glue the top of the box closed.
If the cardboard box flaps meet when all four flaps are folded, there is no need to mark them with a pencil. Apply glue to the entire left and right flap in this case. Place ample padding of tissue paper and bubble wrapping around breakable items in a cardboard box for shipping.
Keep fingers away from the open edges of the flaps when pressing them together to avoid burns from the hot glue.