My previous post on the chemistry of cast iron seasoning focused on fat polymerization – the transformation of an oil into a hard, slick glaze. After I posted that, someone sent me some links that talked about two other elements in cast iron seasoning: carbon and magnetite.
Carbon is the black stuff that’s left after something is burned. A certain amount of carbon gets bound up in the polymerized fat when food is cooked in the pan. This may darken the pan, but does it make it more nonstick? Some say it does, though I don’t see the mechanism.
More interesting to me is the third element: magnetite.
The post after this one on “black rust” describes why you should heat the pan before applying oil for seasoning. This helps the seasoning to adhere and makes the pan pleasantly black.
In a previous post, I illustrated how I cleaned and reseasoned an antique cast iron popover pan. This was my first attempt, and my seasoning technique was somewhat haphazard because I couldn’t find consistent, science-based advice. I used a combination of organic avocado oil and strained drippings from organic bacon. This worked pretty well on the popover pan, which doesn’t have a polished surface. But the smooth inner surface of a skillet showed an unevenness of color and texture, and the seasoning wasn’t hard enough. It was too easily marred by cooking utensils or scraping against oven racks.
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.
The pictures below are both of the same antique cast iron skillet. The “before” close-up on the left is from a picture of the skillet in my previous blog post on making German Pancakes. I stripped the pan with oven cleaner and reseasoned it based on my new understanding. The “after” close-up on the right shows the result.
Griswold skillet closeups: old seasoning on left, new seasoning on right
As part of my recent purge of nonstick cookware, I acquired my very first cast iron skillet – a vintage large-logo Griswold. I removed all the old crud with oven cleaner and then reseasoned it. Rust was minimal, so I was able to scrub it off with steel wool. (For more on cleaning and seasoning cast iron, see my previous post.)
Griswold #7 cast iron skillet, large logo
Griswold #7 cast iron skillet, large logo
I’ve been interested in recipes that use the skillet’s unique properties: nonstick, stove to oven, even heating, and good heat retention. So I decided to make a German Pancake – also known as a Dutch Baby – stuffed with apples. I looked at several recipes and then came up with my own spin on it. I’d never had a German Pancake before so I didn’t know what to expect. I was amazed when I took my first bite. It was exquisitely delicious. Here’s the recipe.
My fascination with popovers began with a new cookbook I purchased just before Christmas. This led to a search for the perfect popover pan, which turned out to be antique Griswold cast iron. That, in turn, led to intensive research on how to restore an old cast iron pan covered with rust and crud. I succeeded, as you can see in the picture below. In this post I’ll describe how to restore a cast iron pan, and then use it to make perfect popovers.
Popovers in my newly restored Griswold popover pan
