I'm starting to prefer the thick rough buildup, it usually comes off better in the electrolysis. It's when it's a hard shiny smooth layer, almost like a plated skillet, that I curse it. I got the Griswold #9 LL scrubbed good after 2 days in the tank, and around the inner walls at the top were those stubborn splotches. I took steel wool to it til they were about as smooth as the surrounding metal, experience has taught me further electrolysis will do little good and since it'll be my new user I'll live with it. (I feel a complete traitor to my Wapak #9, I scarcely knew you yet you were my go-to skillet.)