Well, PTFE is a non-stick substance, so in its natural state it won't stick to the pan. That means it has to be mixed with chemicals called 'binders' - literally to bind it to the metal. And it’s also very soft, so in its pure form it wears very quickly. To overcome this, it’s mixed with hardeners. Most coatings are applied in two layers: the first layer has more binder, to improve adhesion to the pan, and the second layer has more hardener, to improve resistance to wear. And nowadays there are even more sophisticated formulations, using extra elements like ceramic or stainless steel particles. They are all ways of increasing the strength of the bond, and the coating’s resistance to wear.
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