Warped pans
Let a pan cool before checking whether it rocks. Sudden cooling of hot cookware can distort the base. Ask the maker about a bent pan rather than improvising a repair.
Check the cooled pan, not a product list
Set the cool pan on a stable, flat surface and check whether it rocks. Inspect for debris underneath. A maker’s general cooktop permission cannot tell you whether your particular pan has become distorted; none of the catalogue measurements tests base flatness.
Avoid sudden cooling
All-Clad warns against putting hot cookware under cold water. Let the pan cool before washing. Cleaning residue or a rainbow stain does not straighten a bent base.
If it still rocks
Ask the cookware maker about the exact model and follow the stove manual before heating it again. Whirlpool’s glass-cooktop guidance calls for a flat bottom. Do not try to force a hot pan flat or treat its rim diameter as a flatness check.
Updated · The Well Stocked Kitchen