Psst... We're working on the next generation of Chowhound! View >
HOME > Chowhound > Cookware >
Jan 29, 2010 09:36 AM

Chemistry of Cast Iron Seasoning: A Science-Based How-To

The best oil to use when seasoning cast iron, and why (I haven't seen this info anywhere else):

  1. Click to Upload a photo (10 MB limit)
  1. Interesting... apart from a couple of blatantly unscientific statements and an exaggerated photograph to show the unevenness of the shine in the seasoning, it was an interesting read.

    4 Replies
    1. re: mateo21

      Are there inaccuracies? If there are, I'd be interested to hear them. I'm no chemist.

      1. re: permutations

        FTA: " The free radicals then “crosslink” to form the tough, hard film you see in a well-seasoned pan"

        That's very, VERY wrong. Free rads don't form chains, especially the hydroxyl radicals involved in the seasoning process. It's the fatty acids (or I should say the aliphatic component of the fatty acid groups) that polymerize. The free rads generally pick up a hydrogen atom forming water, or a nitrogen atom or molecule forming nitric or nitrous oxide

        1. re: ThreeGigs


          Are you thinking about small molecule radicals? Like hydroxyl radical OH* forming H2O. Yet, large molecules can also become radicals as long as they have a free unpaired electron and indeed there are polymerization initiated by radical centers.

          1. re: Chemicalkinetics

            Yeap, that was my thinking. OH is a heck of a lot more reactive than the hydrocarbon chains, and if I'm recalling my organic chemistry correctly, when the glycerol backbone of the lipid breaks down, you get OH rads, plus free fatty acids, and it's the fatty acids that polymerize.

            And correct me if I'm wrong, but don't 'drying oils' (as mentioned in that linked article) solidify by means of autoxidation? i.e. something tantamount to rancidification? It's my understanding that the polymerization of the oil is not true seasoning, but a necessary precursor to pyrolization in order to form the carbon layer which we call seasoning.

    2. Interesting technique. Better than my set the pan in the oven and let it bake in there 200 deg. method. I am unconvinced that one must use flaxseed oil though. I use canola because that's what is in my kitchen. I won't use olive oil (also in my kitchen) because it is too expensive to waste and has a low smoke point. I seems to me if you did the high heat method six times you would get a pretty smooth and good finish with any oil. Anyone else have an opinion?