Toothpaste is then injected in the open end and the tube is heat sealed. This complex process allows for the production of a tube with a sealed in-between layers of a printed surface, antistatic agents, and aluminum foil for stiffness. Another ordinary example of coextruded produce is foamed core. In its extrusion process a foaming agent produces a cellular structure which is airy and open. The foamed core a light weight and stiff.
Plastic film is formed by either slot casting or blown film extrusion.
Slot casting produces transparent film. The roll freezes the hot plastic into a nearly amorphous structure. This amorphous molecular structure produces a thin transparent plastic film. The tube is pulled vertically and pinched closed at the top. A larger bubble stretches the plastic producing a thin wall.