Seasoning is a mix of carbon and polymer created from fats. It is susceptible to high heat, acids and physical actions(scraping). You will never have a bullet proof seasoning unless you do not use your pans. It will always be created and destroyed. Some of the best advice you can get is don't heat it too high, don't cook very acidic ingredients too long and its okay to wash your pan. Okay let's do this. I'm feeling generous today. sigh
Saturated fats: Don't have any available double bonds to create a polymer.
Monounsaturated fats: Have only one double bond available to bond with another molecule to create a polymer
Polyunsaturated fats: Have multiple available double bonds to bond to multiple molecules creating a stronger polymer.
Cooking oils are composed of these three types with different percentages of each. Some like avocado oil are low in mono and poly and high in saturated fats(do not bond without breaking the molecule).
Scroll down to "Comparison to other vegetable oils" to find %
https://en.wikipedia.org/wiki/Grape_seed_oil
Oils high in polyunsaturated fats are considered drying oils. They use oxygen to form polymers that make them hard. These will harden at room temperature over several weeks. Polymerization happens at room temperature, increasing the temperature(heating in an oven) increases the rate of polymerization. They have been used in woodworking and oil paints for centuries(?). Ex. Flaxseed aka linseed and tung oil.
The bonds are what create the polymerized layer of oil(aka seasoning). The oils only chemically bond with each other but physically bond with the pan. Meaning the pan can not be too smooth. It has to have a slightly rough surface for the polymer to adhere.
According to some people you need to reach the smoke point(aka burning) in order to break the molecular bonds for them to bond together to create a polymer. You don't need to do this. This only needs to be done with saturated fats which also creates smoke because they are burning. This creates carbon as well as a polymer. One thing I don't know is whether or not the added carbon creates a better seasoning.
You need to use the correct oil with a high amount of polyunsaturated fats and heat to under smoke point of that oil. I don't go over 375°f for any oil.
Some oils seem to be too high in polyunsaturated fats and may become too brittle and flake off such as flaxseed. Ive never tested flaxseed so I don't know the reason but I suspect people heat their oil or seasoning too high. I believe all seasoning will eventually flake due to the nature of heating and cooling and also heating high enough(ei browning meats) over normal use.
Heating your seasoning too high will also begin to burn off and begin to flake. Temperatures over 500°f will burn off your seasoning. Think about oven cleaning temperatures. It will burn everything in the oven. This is also why grill(BBQ) grates will also rust. The fats from the food just eventually burn, leaving bare iron that will rust.
Okay, after all of that the recommended oil is usually grapeseed oil. I haven't used it since I've had corn oil which worked well enough for me.
Its possible to blend oils to attain the holy grail of seasoning but I don't have the money or time for all of that.
My method for seasoning in a oven:
- Apply a thin layer of high polyunsaturated fat to pan
- Place pan in oven(edit #3: place them upsidedown), heat to 375°f for 20 mins.
- Remove and add another thin layer every 20 minutes for a total time of 1 hour.
- Turn off oven and let the pans cool completely overnight inside the oven. The pan will stay hot/warm for 6+ hours. This allows the polymerization enough time to completely harden.
You can also heat the pans on the stove top just under smoke point and add layers this way. Its just more difficult to get all the oil to polymerize this way.
I think that's everything, if I forgot something its because my brain has become mush.
Good luck!
Edit 1: I swear is someone says I used ayeeye for this I'm going to quit.
Edit 2: over time the polymers will eventually become more carbon(through heating) over time, that's why pans become dark black. Again I don't know if this technically weakens the "seasoning" or not
Edit 3: place the pans in the oven upside down
Edit 4: I just checked the smoke point(burning) off flax seed. Its apparently 225°f. Which is the reason I suspect it flakes so easily. It just burns off easily.
