Take the 2-minute tour ×  I'm sure everyone's seen this - that
brownish stuff left behind when you grease an area of a baking
dish that gets left exposed to the heat. Soap doesn't bother it
too much, and it likes to gum up my scrubber. What's going on
there, and are there any easy ways to get it off?  share|improve
this question  3 Answers 3  up vote 6 down vote accepted  When
oil gets overheated, it turns into a polymer that is insoluble
in water, even with soap.  The best way to clean this up is with
Barkeeper's Friend, Bon Ami, or a similar solvent (I think
they're all alkaline-based solvents). It's non-abrasive, and
safe to use on almost all cookware without leaving marks.  Edit:
To help prevent this from happening in the future, use a paper
towel to wipe off any excess baking spray on the edges of the
baking dish that won't be covered by food.  share|improve this
answer To expand on what Bob said -- basically, the oil
polymerization is the exact process that you're trying to get
when you season cast iron