Does the bottom of an old raw iron skillet bulge out?

The bottom will bulge.

Generally, iron pots are a little rough, which is unavoidable, and will become smooth after a long time. There are blemishes, small raised part of the general iron, the quality of the pot does not affect the quality of the pot, but a small pit on the quality of the pot is more harmful, the bottom of the iron pot raised unevenly, you can burn the pot red-hot, the leftover heat to find a flat and hard to make a strong pressure will be pressed flat.

The benefits of pure iron pan frying

With iron pan frying can supplement the iron element. At high temperatures, a small amount of iron in the iron pot will seep into the food, and therefore objectively play a role in iron supplementation.

Using an iron skillet to stir-fry can put less oil. Iron pan used for a long time, the surface will naturally generate a layer of oil, basically equivalent to the effect of non-stick pan. You don't have to put too much oil when cooking, thus avoiding the intake of excessive cooking oil. To clean an iron skillet, you don't need to use detergent, just use hot water with a stiff brush and let it dry completely.

Traditional iron pots and pans are protected from the potentially harmful chemicals in the non-stick coating. Non-stick coatings often contain carbon tetrafluoride, a chemical that can harm the liver, affect growth and development, and even cause cancer. Traditional iron skillets are not coated with this chemical and are naturally free of this danger.