It is said metal utensils scrape teflon coated non-stick pans and should not be used on them. All sources I found say just that. But when my metal utensil doesn't have sharp edges and I am not pressing on it with more strength than a wooden one, why should I use a wooden one over a metal one? Is there any chemical or other reason beside scraping the coating with the sharp metal edges? Not all metal tools are sharp.
1 Answer
Metal is a lot harder than wood, which means when it hits another surface, it won't deform on a microscopic level the way wood does. This means that, while a wood utensil rubbing against a nonstick pan will get compressed a bit, the metal utensil will rather cause the nonstick surface to get compressed, which results in scratches and other damage to the nonstick surface. You can use a fairly large amount of pressure with a wooden utensil and still not damage the nonstick coating, since the wood is not nearly as hard as the coating. However, metal utensils don't need to do much more than brush the surface of some coatings to scratch them, since they are much harder.
For this reason, metal utensils don't have to be very sharp in order to scratch a softer surface. Think metal balls rolling on a glass/plastic surface: they will scratch and scuff the surface, even though they are not "sharp" at all.
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5And hard non-metal things (ceramic knife for instance) are just as bad as metal for teflon. Commented Sep 23, 2022 at 16:16
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5@MarcGlisse Worse potentially. The higher up the Mohs scale you go, the worse it gets. Not that anyone sensible has diamond-encrusted kitchen utensils, but if those existed, they'd destroy almost any pan they touched... Commented Sep 23, 2022 at 20:43
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4Metal balls rolling on a glass surface won't scratch it unless they're ball bearings: glass has a higher scratch hardness than most steels. (Ball bearings are made from an exceptionally hard steel.)– MarkCommented Sep 23, 2022 at 23:40
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3(+1) Nailed it. Always nice to see an engineering-correct explanation on a non-engineering site (full disclosure: yes, I'm an engineer :-) Commented Sep 24, 2022 at 11:54
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3@KarlKnechtel ① I ruined a non-stick pan boling an alkali solution in it - I was trying to remove very thick burnt residuals without scraping, I removed also the non-stick coating... this is similar to a dishwasher, while handwashing implies lower temperatures, less aggressive detergent and lower water pressure ② the water in a washing machine possibly contains burn hardened residuals that are trown at relatively high velocity on the non-stick surfaces– gboffiCommented Sep 25, 2022 at 21:28