Summarize the following:
This will eliminate the rust, and it works no matter whether you have a few spots or the entire skillet has gotten rusty. Get a big pot large enough to hold the skillet. Fill it with a solution of half white vinegar, half water. Place the skillet in the pot and make sure it's completely submerged. Soak it for at least 3 hours so the vinegar has time to dissolve the rust. When you remove the skillet, check for rust. If you still see rust spots, use a scrub brush to scrub them away. Don't soak the skillet for more than 4 hours, or the iron will start to degrade. You just want to soak it long enough to take off the rust. Rinse off all of the vinegar, then use a dish towel to completely dry the skillet. Just like you would for a brand new skillet, use a paper towel to rub lard, olive oil or vegetable oil all over the skillet. This will become the skillet's new seasoning. Put it in an oven preheated to 350F (177C). After 2 hours, remove the skillet and let it cool completely. Coat it in another layer of oil, bake for 2 hours, and allow it to cool again. The once-rusty skillet should now have a protective layer of seasoning.
Soak the skillet in a vinegar solution. Rinse and dry the skillet. Coat it with fat. Bake the skillet for 2 hours. Repeat the process.