Question on Rehabbing Old Cast Iron
I have a 10" Lodge frying pan that I've had since college. I never even tried to season and washed it in soap for its first ten years of life. For the last two, I've regularly seasoned with bacon fat.
My question is that I'd like to strip it and start from scratch. I've given it two hits with oven cleaner, and most of the black patina came off but some patches just wouldn't. After that I've scrubbed it thoroughly with steel wool and antiseptic soap, dried it out and am ready to apply the first coat of Crisco.
Should I be worried about the patches (particularly along the walls of the interior) that underwent an application of oven cleaner but didn't come off?
I am no cast iron pro, but I would simply sand paper the rough spots and be done with it. Pumice grill brick and vegetable oil may be even better, but it is a tad nasty to do.
If there is a heavy carbon buildup then sand paper, grill brick, or even some grinders may just glide over it. You need then quick and high temperature torch to blast that stuff off. I do not mean the LP or MAPP gas torch but one that actually can cut metal.
I decarboned and reseasoned a large 200 gallon kettle utilizing the above methods with a final seasoning using hog lard. It went for mint on ebay.
My pet peeve is anyone taking soap to my cast iron cookware. Worst soap is Dawn, as I can taste that crap weeks later.
Now for those that feels it necessary to use soap I suggest an apple flavored soap. It goes better with the morning bacon and eggs. ;-) After cleaning with soap do not forgit to reseason it, strip it with 2 cups water and a tsp-cream of tarter, and reseason it for use for actual use. Soap "perfumes" gets deep into the pores and is a bear to get out.
Cleaning cast iron with nothing more than hot water and a dry towel is my daily cleaning ritual. I lard coat after drying. If I should cook scrambled eggs it cleans up best from a cool down and return to the burner with plain water till hot. (Not to an actual boil) It should wipe clean ready for a final coat before putting it away.
A metals website that I found strongly disagrees with the clean-by-intense-heat scenario. It can lead to cracking (cast iron is not indestructable) and if badly cracked, can explode during use with high heat.
These folks are antique cast-iron collectors, and have devised an electrolysis method for removing the crud so as not to harm the precious collectables. This might appeal to the Popular Mechanics types out there.
I have no such special apparatus, which involves a dip and electrical charge, so I use the fireplace coals method.
Not a roaring fire, but banked coals from a medium sized evening fire. Place the pan upside down over the coals and let the subsiding heat work on the gunk. It does take several sessions to get all the areas, but I feel safer with the lower heat. No exploding pans for me, thank you. ;-)
I also agree with the recommendation that yo run it through the self cleaning cycle in your oven. It works like a charm. You will see some oxidation when you remove it from the oven. This will wipe right out and then start seasoning and don't try to use oils for seasoning it. They will leave a sticky redidue. Just start cooking bacon, a lot of bacon.
re: Sam Harmon
That's probably as good a reason as any. I might well do the same.
I agree with the above poster about getting the pan really hot to burn off any nasty stuff that may have accumulated. Since you're planning to reseason anyway, no harm in getting it glowing. You could do this just as well using a burner on top of the stove. If you have a fireplace or something like that, you could just throw it into the coals for a while. You ought to be able to burn off the stubborn seasoning patches, as well as any oven cleaner residue.
Once you've done that, just scrub it clean and treat it like brand new. The lodge web site has pretty clear instructions if you need 'em.
Assuming you have a self cleaning oven, I'd strongly suggest running it through that before you start. Maybe soak it in the sink for a few minutes to get rid of that even cleaner - not like overnight, you don't want the thing to rust, but maybe for half an hour or so. Maybe change the water a couple times? Next time (if there is a next time) go simply for the self cleaning oven, no need for chemicals. Just hope you didn't "season" your cast iron with oven cleaner.