Linseed (flax) oil is kinda famous for becoming rancid quickly. And, so, you're saying that it is also indicative that it is quick to polymerize.
Grape seed oil has a similar reputation.
So it seems there is at least a mild challenge of getting the oil from the plant into the bottle and from the bottle into my pan. Just simple storage can be tricky. ??
So, at cooking temperatures, any oil will polymerize, right? And then it doesn't really matter which one does it at the lowest temperature, but which one will do it more evenly and result in a slipperier surface.
In fact, we might end up with different fats that polymerize in different ways. Some might leave a super slippery surface, but be poor for the first layers on iron. Some might help fill in a pit or fill in a rough (new lodge) surface.
I know that I have had times where fats will leave a polymerized layer that is a thin, contiguous layer. And other times where fats will leave a layer that is "mottled" or "spider-web-ish". I suspect that there are a lot of factors here, one of which could be the different types of oils. It might even be compounded with the type of oil/layer from the previous use of the pan.
I guess my point is that it is results that count. And the real results would be to try a dozen different types of fat cooking the same thing five times in a row and to conclude which was the best on the fifth time.
The smoke point of various fats is important to note because a fat is no longer good for consumption after it has exceeded its smoke point and has begun to break down. Once a fat starts to smoke, it usually will emit a harsh smell and fill the air with smoke. In addition it is believed that fats that have gone past their smoke points contain a large quantity of free radicals which contibute to risk of cancer.
Why? Why eliminate soy and canola oils? I used canola oil thinking it had a higher smoking point -- and I had some on hand because I was using it to remove rust from my tools. It comes in a spray can just like WD40 (!)
According to the chart olive oil - which I more normally have in my kitchen has a higher smoking point. I guess peanut oil would be a better frying oil.
Craig Storms wrote:Chemistry of Cast Iron Seasoning: A Science-Based How-To
Chemistry of Cast Iron Seasoning: A Science-Based How-To
I wanted to understand the chemistry behind seasoning so I’d know how to fix this, but there is nothing that addresses this issue directly. A Web page on cast iron posted by someone similarly obsessed with the science gave me two crucial clues, the phrases “polymerized fat” and “drying oil”. From there I was able to find the relevant scientific literature and put the pieces together.
Mark Tudor wrote:I have a Wagner that had been sitting in a drawer for a couple years that I pulled out and cleaned off using Sheryl's tips- no self cleaning oven, so I sprayed oven cleaner over it and tossed in a plastic bag to sit for a day. I cleaned that off the next day, wiped off a tiny bit of rust that started after the coating was gone, and then coated it all with the organic, food grade flax oil I bought for this. Wiped it down and tossed into the oven at 450 or so for an hour, then let it cool and repeated 5 more times. After it cooled off the surface was smooth and not tacky at all.
Looked great afterwards, I put some olive oil in the pan and heated it up on low/medium heat (4 of 10 gas heat) and once it heated up I tossed an egg on to cook. It stuck quite a bit, and I saw numerous little bits of coating flaked off. I was using the metal spatula Paul recommended in his article but wasn't scraping hard. After I was done it took some work to clean the surface and a lot more little flakes came off, and almost all of them were around the middle, which is where the flame was sitting when on low.
Not sure if even low heat was enough to soften the surface here, but this was far less effective than the first time I seasoned the pan, which I think was with canola oil around 5 years ago. Not sure if I can scrub the surface down until no more flakes come off, then toss back in the oven to add more coats, or if I need to use the Easy Off again and get it back to bare metal, and then try it again using Alex's idea of heating it to 350 and applying coats that way. I notice the chart shows the smoke point of flax is 225, so aren't we hitting that smoke point anyways if we season at 350? Maybe just not as bad as 450-500?