Don't wash Cast Iron with soap?
The seasoning layer on the surface of the pan is formed when the pan is heated while in contact with some fat or oil. Flax seed oil is most commonly used to deliberately achieve this effect before using the equipment to cook with. The result is a chemical reaction with the fat molecules called "polymerization" in which small fat molecules gather together to form larger ones that then bind to the cast iron surface.This "fat polymer" is what we call the seasoning layer, and guess what... it isn't dissolved by soap. However, I would strongly suggest against this. While using soap might not actually ruin your cast iron the seasoning will definitely taste like it. Well yeah, I guess that would be what you call ruined! I admit I am guilty of having washed some of mine every "wrong way" imaginable before learning the proper way to care for my cast iron. I have pieces that I can remember having cooked with after having washed with soap and don't remember ever tasting it at the time. I've seasoned them since and still use them today, they are unstoppable. It really is all about the seasoning of the pan. It gives proteins a one of a kind flavor in searing that I personally am a huge fan of.
Do not wash your cast iron with soap and definitely don't use harsh detergents, abrasive scrubs, dishwashers, or soaking to clean them. The best way to clean them is with Salt. With a moist towel, the salt acts as a natural abrasive and dissolves any attached food without harming the seasoning.- K.C.C.