I scrubbed the gunk off this old BSR (?) kettle, and tried the salt & potato scrub to remove what I thought was rust, but this still remains. Is this rust, or symbolic of that rosy-colored burn from being subjected to high heat/fire? If it's the latter, is it still usable once seasoned? Just want to make sure before I soak it in the oven cleaner.
Thank you!
Thank you!

