Some toothpastes have the fluoride or mouthwash incorporated as a stripe.
The standard cleaning mixture is usually chalky white, while the fluoride or mouthwash is often a clear blue or red gel. The two pastes are mixed separately. As with all toothpastes, the empty tubes, called blanks, are filled from the wide end, which is then crimped and sealed. The two pastes contain colours that will not mix, so the pastes so not flow into one another. When the toothpaste is squeezed out of its tube, white and coloured stripes emerge.
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