The small, colored rectangles found at the crimped end of toothpaste tubes have been the subject of persistent online rumors. These rumors often suggest the color indicates the chemical composition of the paste, with different colors supposedly representing varying levels of natural or chemical ingredients. However, this interpretation is not supported by scientific evidence or manufacturing practices within the industry.
In actuality, these marks serve a practical purpose within the manufacturing and packaging process. They are registration or eye marks utilized by optical scanners on high-speed packaging machinery. These sensors detect the marks, signaling to the machine where to cut, fold, and seal the tube precisely. The color is chosen based on contrast with the background of the tube to ensure reliable detection by the sensors, optimizing the efficiency of the production line.
