The following experience might help.
A few months ago I accidentally left an aluminium grill pan in an
oven that I switched to maximum temperature for an hour or so. The
grill pan was made of 0.7mm sheet aluminium and was originally very
rigid. After the accident it was very discoloured with burnt-on
grease, and exceedingly soft. So soft, in fact, that very mild finger
pressure would bend it. Attempts to clean the burnt-on grease caused
major distortion. It was far too soft to be used as a grill pan.
A friend suggested that sand blasting would both clean and harden
it, and since it was totally useless as it was, there was nothing to
lose by trying it.
The result was amazing. All the burnt-on grease was removed, as
expected, and the hardness was restored totally. We were both
surprised by the amount of hardening produced by the sand blasting.
The grill pan is now back in service, as good as new, except that it
now has a matt finish instead of smooth. Not that that matters for a
Regards, Gary Wooding