If your seasoning is flaking off, that means there is moisture underneath it. Use a dry scouring pad to take it off. If you see rust when you take the outer layer off, use a Brillo pad to thoroughly remove that. After completely stripping the pan down, wash it in hot soapy water, rinse thoroughly and dry. Heat the pan on the stove to evaporate any remaining water. Fill the pan to just below the rim with coarse kosher salt. Morton's is fine. Pour regular Wesson cooking oil over the salt (not corn oil, because it just doesn't work well, and I don't know why). The oil should come to just below the top of the salt, but not slosh around. Cover it tightly with heavy duty foil or the lid, if it has one. Bake this in a very hot oven for one hour, then turn down to medium and bake another hour. If your pan has a lid, you can clean the lid the same way, and put it on top of the pan while you bake it. Be sure to have plenty of ventilation, because there will be smoke. Plan to run a fan. If it smokes too much, turn it down and bake it longer to make up for lower heat. The process utilizes a chemical reaction that is dependent on time+ heat+ oil+ salt.
After the baking is done, your pan should have a glassy, pebbly surface. Let it cool, then dump out and discard the salt/oil. It can be used for a defoliating scrub for dry skin, if you want. Not good for anything else.
The Dire Wolfess