Fighting flash rust on cast iron pans

Question

I completely stripped the seasoning off of two pans with the intention to start the seasoning process over from scratch. One pan I had messed up the seasoning (skillet) and the other (sauce bowl) was on clearance because part of the seasoning was scratched and was an "easy" fix.

I used the oven cleaner method and finally got everything down to the bare metal. I went to wash everything off and did a vinegar rinse to neutralize the oven cleaner and rinsed everything in cold water.

Initially, I tried drying the pans in the oven before applying any Crisco to start the seasoning process, but the flash rust got to the pans first. I started completely over again from square one repeating the oven cleaner method. I had read that you can do a quick dry and apply your oil pretty much immediately then place the pans in the oven to dry at a lower temperature. Tried that and began the seasoning process by wiping off any excess oil and baked the pans at 450 deg for about 1 hr. After the pans had cooled, they came out looking brown, almost like flash rust stuck through the seasoning process as opposed to the beautiful iconic black everyone thinks of.

My question is - did I miss anything or do something wrong in this process? I had watched so many videos and read so many blogs and I thought I had followed along pretty well yet my results didn't match anyone else's.

Answer 1

The brown stuff is presumably polymerized oil, AKA "seasoning". At sufficient thickness, it appears black (but blackness is unnecessary for it to be effective as a surface treatment). I don't see any sign of rust in those pictures.

Answer 2

The other answer is right to point out that recently done seasoning can be brown rather than black. It is still important to make sure it's not rust below a first thin nonblack layer of seasoning. You may want to scratch a little bit off and check the texture, to see if there is rust below the slick surface.

Normally such rusting shouldn't happen, but you wrote that you used a vinegar rinse. Vinegar on unseasoned iron is very likely to result in rust, and even if you didn't notice it before putting it into the oven, the temperature can have enhanced the reaction. So, don't use vinegar on any other acids.

If it should turn out to indeed be flas rust: I have successfully removed it with a strong lye (NaOH in water). Luckily for you, it will strip the new seasoning before it gets to the rust, so you won't have to take multiple steps. After you have cleaned it off, do not neutralize it in any way. Just wash it off with plenty of fresh water, multiple rounds. Then season it. If you see soapy esters emerge when you apply your fat, go back to the washing and drying stage.