Being who I am, I undertook researching the particulars of this process. Here is what I found.
Flaxseed oil (also known as linseed oil) belongs to a class of oils known as 'drying oils.' These oils earned their name because they are particularly susceptible to polymerization when exposed to oxygen, especially in the presence of a metallic catalyst such as iron. It is this cross-linking of the oil's molecules which forms the hard non-stick coating on cast-iron pans, and is the reason these 'drying' oils are used as the base for oil paints and varnishes. They will form this coating on their own (gradually congealing over time), but putting them in a hot oven speeds the process dramatically.
So I dug deeper. I wanted to find out how much better flaxseed oil was as a seasoning agent than oils such as coconut (which is what we've been using lately), corn, etc. I discovered that the polymerization potential of an oil can be expressed as something called the iodine value (IV), and that 'drying' oils are those oils with an IV of 130 or higher. I tried really, really hard to find a table or list of the IV of different oils, but it turns out that all the
really good lists that Google knows about are locked behind the paywalls of professional journals. Fortunately I managed to find some help from sites devoted to the DIY manufacture of soap and biofuels (it gets inconvenient when oil turns to shellac in your tank!).
Coconut oil - 10 (10??? Sheesh! No
wonder we have to reseason so often!)
Olive oil - 80 (getting better...)
Peanut oil - 93 (now I know why peanut was my personal favorite for so long)
Canola oil - 98 (slightly better than peanut)
Sunflower oil - 125 (Now we're getting somewhere!)
Soybean oil - 130 (right on the border)
Tung oil - 168 (Now we're
really talkin')
Flax/Linseed oil - 190 (Wow. That's really up there)
And that was pretty much it. I couldn't find anything with a higher IV than flaxseed oil...for a really long time (because I ain't gonna pay $35 for access to professional journals for a project this casual!), but eventually I
did manage to find one higher than flaxseed. It turns out that
perilla oil has an IV of about 195, which theoretically means that it should be even better at seasoning pans than flaxseed...if you can
find some, that is. I was only able to find it in
a $25 2oz size for skin care (but diluted with vitamin E oil) or in
a $50 gallon jug (though they do have it available in a 40lb pail or by the drum, too).
We're debating getting the gallon jug and just having a seasoning party with some tossed greens and maybe a deep-fried chicken. Who knows?
--Geekboy
