I recently bought a large iron frying pan, the de Buyer Mineral B Element Round Country Frypan (32cm). The manufacturer's Web page for this product includes a symbol indicating that the pan is compatible with ceramic-glass cooktops.
The bottom of the pan is nearly flat when cool. But when I heat the pan on my ceramic-glass cooktop, the bottom becomes rounded. As a result, the bottom contacts the cooktop at only one point, and the pan heats unevenly.
The temporary rounding presumably results because sections of the pan expand differently when heated.
Is there anything I can do to make the pan usable on this cooktop? Is there some kind of mesh heat diffuser that I can place on the cooktop and that the pan will sink into to achieve even contact?
I wrote to de Buyer with this question and received no response.