My Dutch oven stood for a whole year outside in the fireplace, where it could not get wet, but still it rusted.
I tried several things in the past few weeks, like scrubbing it with a potato and course salt, and even electrolysis, but not luck.
Then I tried something new, to “burn off” the rust, but heating it up on my diy forge, and then going at it with a steel wire brush.
This worked very well, and then I seasoned the Dutch oven as well.