Is it really necessary to avoid using soap on a cast iron skillet? Hello Seasoned Adviced community! 

When talking about cast iron skillets, it is common to hear the advice "don't ever use soap to wash the skillet." However, I rarely hear specific reasons for why it would be necessary to avoid using soap on a cast iron skillet, and I can't think of a valid explanation for why this must be true. 

An article on Serious Eats calls the "no soap" advice a myth, stating the the origin of the advice is the idea that since soap removes oil, the seasoning of the pan would be ruined by using soap. But, as the article states, the seasoning of the pan is a thin layer of polymerized oil, which is a plastic-like coating on the surface of the pan, and soap won't hurt the coating. There is a chemical bond between the coating and the pan which soap can't damage. 

So, will using soap on a cast-iron skillet damage the skillet or is this a myth?
Here's the deal ... if your pan is seasoned correctly using an oil with a high iodine value, then no, soap won't harm it.

If it's not seasoned correctly, then it could need a strip &amp; reseason.  If you're using a low iodine oil (the surface will be slightly tacky when the pan is cool), then it also might ablate the surface somewhat, and repeated cleanings could damage it.

If you think it needs a deeper clean, one approach is to always add a new (thin) layer of oil after cleaning the pan (and then heating it 'til it smokes) ... this means that you'll have a relatively thick layer of seasoning and if you lose an individual layer, it's not a big deal.  (and you'll add it back right after the cleaning).