Hello,

I inheirited a very black cast-iron pan from my mom. I enjoy cooking
in it--it is very nonstick and it seems easy to clean by simply
deglazing with hot water and scrubbing well with my regular nylon
dish-cleaning brush. After each use, I dry the skillet thoroughly and
apply a thin layer of canola oil. In fact, I'm a bit obsessive about
this.

My problem is this: I keep getting rust spots developing on the bottom
of the pan. I can always remove them by scrubbing the spots with a
mixture of salt and oil, but they keep coming back. Also, on the other
side (the cooking side), it _looks_ like there may be rust _under_ the
blackened patina. It's very hard to tell--it's not obviously dry,
powdery rust like I get on the bottom, and the way that light reflects
off the surface, the redness may be a figment of my imagination.

I do not know how well the pan was treated before I got it, but I am
guessing not very well. It was sitting in my parents' basement for
years before I rescued it. They probably got it from my grandma, who
was a notoriously bad cook.

My question is: could there be rust _underneath_ the seasoning/patina
layer? If there is, I think I'm just going to buy a new skillet, since
it does not seem like it's worth it to remove all the seasoning, then
remove all the rust, then reseason when I can get a new, preseasoned
skillet for twenty bucks at Amazon.

Thoughts?

Thanks,
Matt