Vintage Pans, Old-School Rules
The idea that cast iron and soap don’t mix dates to the days when household soaps and cleaning agents included harsh active ingredients like vinegar and lye. These old-fashioned soaps were avoided for good reason: acids like vinegar can strip seasoning, and lye-based products can damage both seasoning and the underlying iron.
Today, most dish soaps don’t contain harmful, abrasive ingredients and are perfectly safe for use with cast iron cookware and just about everything else in your kitchen. These modern soaps can be classified as de-greasers: they’re designed to cut through tough, greasy stains, making it easy to remove lingering food residue. If you have stubborn or strong-flavored residue on your skillet, a hit of soap will help.
So, it’s fine to soap up your skillet! Here are a few tips on when to lather up:
Washing Cast Iron with Soap