The side stripe is a stripe of protective lacquer applied inside a food can over the weld where the body is joined. Three-piece cans are made by curling a flat sheet into a cylinder and welding the seam; the heat of welding destroys the tin coating along that line, leaving bare steel that would corrode in contact with the food. The side stripe reseals it, sprayed or rolled onto the interior over the weld before the can is filled. Without this narrow band of coating, acidic or salty foods would attack the exposed metal, causing off-flavours, hydrogen swelling, or perforation. It is a small detail of can manufacture, invisible to the consumer, on which the integrity of the whole pack depends.