how to clean carbon steel

Thanks to all who responded. They weren't that rusted and a little bit of steel wool cleaned them up nicely.

If it's just a small area you can scrub it off with a nylon scratch pad (those green scrubby things). You can sprinkle a bit of salt too, to help with the scrubbing. You may not even need to re-season.

If it's a much larger area, I agree with the vinegar bath idea below. And yes you would need to season in this case.

Fine steel wool will work.

So will a bath of 50% distilled vinegar and water.