I have used cast iron for many years and done some research on the process of seasoning cast iron. Here is what I have learned. The brown sticky stuff is gross and is caused by one or more of 3 things:
- The layer of oil applied is too thick.
- The baking temperature is too low.
- The baking time is too short.
If you want to love using cast iron you need to season it correctly. Here is a link to the best explanation I have found so far to explain what seasoning is, how it works, and what works best and why. http://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/
Here is a simple step by step instruction of how to do it right: https://www.cooksillustrated.com/how_tos/5820-the-ultimate-way-to-season-cast-iron I recommend adding a step before step 1. Heat the raw cast iron in the oven at 450 degrees F for an hour and let cool. An explanation of why this is helpful can be read in Sheryls other blog entry.
If you have a brown sticky coating you have to get it off. When I recondition a dutch oven or a skillet I use a sandblaster with glass abbrasives in a blast cabinet, followed by a palm sander to flatten the metal, followed by and a 6" circular wire brush on a bench grinder, followed by a 3" wire brush in a die grinder. Now I understand not everyone can strip cast iron this way. Depending on how the condition of your iron you can try oven cleaner spray, heating in your ovens cleaning cycle, or you can strip it in a hot camping fire. Remember to let it cool slowly. The point is you have to get that crap off and get back to bare metal.
Don't use the wrong oil. Don't use vegetable oil, corn oil, safflower oil, canola oil, butter, bacon grease, Crisco, olive oil, etc. All of thes oils will turn black if aplied thin enough and heated to a high enough temperature for long enough and give you a cooking surfac. BUT you could have one of the following happen to you:
- If you get it too hot, it will flake off.
- If you scratch it, it will flake off.
- Some oils like olive oil will give you a mottled surface.
To season it right you NEED TO USE one of the following and heat to a high enough temperature:
- Flaxseed Oil (from the refrigerator section of the health food store)
- Linseed Oil (Yep, from the hardware store)
Why do you have to use one of these oils: The short answer is because these have high amounts of omega-3 fatty acids needed to produce crosslinked polymerization. Before you get all over my case that lindseed oil is not a food product, note this, after heating to 500 degrees F, no oil is a food product any longer. All oils will undergo chemical changes and become something different. The difference is lindseed oil and flaxseed oil will become a hard, crosslinked, polymerized, durable layer bonded to your iron that won't flake off into your food even when used at high temperatures.