Someone PM'd me and asked me to explain how I restore iron, so I'm posting below rather than replying to PM as this isn't a secret at all just stuff that I do that isn't in any online how-tos that I've seen.
Hi Anthony
there's nothing secret about my method, there's just a few things I do that aren't captured in any of the how-tos online
So let's assume that you've found a nice old Griswold #8 skillet in a thrift store (hey we can dream right?) but it's covered with crusty black stuff and worse, it was used by someone who didn't know how to care for it so there's some surface rust on it as well.
Step 1 for me is to get a bottle of lye crystals and mix it with water in a 5 gallon bucket (WITH LID - it'll smell pretty bad after it starts working) and then throw the skillet in until I feel like dealing with it.
Step 2, which you can skip if there is no rust, is a couple days in an electrolytic derusting tank. I just use another 5 gallon bucket, some plastic clamps, some rebar scraps, and an Astron 12V power supply (or you could use an old manual battery charger) that'll cook off all the old rust. I started doing this with old car parts back when I did stuff like that, but it works great on iron cookware too.
Now here's where the tricks come in. Before seasoning, I'll scrub the piece well with soapy water, then follow with a good scrub with a Magic Eraser to hopefully start pulling all the converted rust out of the pores of the metal. This will destroy the Magic Eraser but the goal here is to get the metal squeaky clean. Then I season using Jeff Rogers' method as detailed here:
http://theculinaryfanatic.com/cast-...nance/jeff-rogers-cast-iron-seasoning-method/
Jeff uses the blue disposable shop towels for wipe off; I use terry cloth towels from the auto parts store. Both work, but the key thing is that PAPER TOWELS DO NOT WIPE OFF ENOUGH OIL. you will get spotty seasoning unless you use something more absorbent than regular kitchen paper towels.
The other thing that I do that is not mentioned in Jeff's write up is if I am seasoning an old piece that has been stripped and derusted, I will hold the oven at 200F, wipe on some Crisco (or lard, or beef tallow, or whatever you prefer) let it sit at 200F for about 10 minutes, then wipe it off as if I am going to proceed with seasoning. If I see ANY brown or grey on my wipe off rag, I will wipe on some more Crisco and let it sit for another 10 minutes, then wipe off again. Repeat this as many times as necessary. The reason I do this is I have found NOTHING that will pull as much contaminants out of the surface of the metal as the hot oil, not soap, not Magic Eraser, not anything. The oil is the finishing clean before seasoning. Then after I get to the point where my wipe off rag comes off clean, I follow Jeff's method and let 'er rip, I usually season 3-4 times and then the pieces can be used. Baking cornbread in a skillet is a great way to break it in after initial seasoning, when I make it I set about half the butter aside that the recipe calls for and put that directly in the skillet. Then the other half goes into the batter. Pour the batter into the preheated skillet with melted butter already in it and bake per directions. Et voila, you have cornbread to go with your chili and have gotten one step closer to that good old Grandma quality black seasoning that only develops over time.