Strip it with a wire cone brush on a power drill (wear full face shield!). Then start with ~60 grit (EDIT: sandpaper). Once sanded smooth move to 80 then 100 grit.
Once you’re done, give it a rinse, wipe dry thoroughly, and then season immediately or it’ll rust.
I like to initially season by heating to a very hot temp, and then using flax seed oil on a paper towel held by tongs, and brush thin layers of oil on that will smoke and turn amber colored immediately. I don’t like the oven method that people write about on the internet, because the seasoning doesn’t last, it takes forever to do, and it takes way more energy to hear and cool. The “wipe oil on to hot skillet” approach works better and only takes a few minutes.
Cheers. I'd realised it was quicker to heat the pan on the stove than in the oven but it hadn't occurred to me to apply more oil while it was hot. I'll give the sanding a go.
Once you’re done, give it a rinse, wipe dry thoroughly, and then season immediately or it’ll rust.
I like to initially season by heating to a very hot temp, and then using flax seed oil on a paper towel held by tongs, and brush thin layers of oil on that will smoke and turn amber colored immediately. I don’t like the oven method that people write about on the internet, because the seasoning doesn’t last, it takes forever to do, and it takes way more energy to hear and cool. The “wipe oil on to hot skillet” approach works better and only takes a few minutes.