Oil, especially canola oil (bad, unhealthy oil), should not be used. If a quick oiling (not seasoning) in between is desired, it's best to use a high temperature oil like avocado. A quick rub can do the trick, if your pan looks a bit dry. I have one pan that is about 100 years old!
Unsaturated fats have a chemical makeup that is more optimal for polymerization, the process that needs to occur to develop the perfect cast iron seasoning. So steer clear of oils with a higher concentration of saturated fats, like coconut oil and palm oil.
Common cooking oils like olive oil will gradually produce seasoning, but won't be as effective as grapeseed oil. Canola, other vegetable oils, and shortening are a little better.
Olive oil wears off cast iron faster than other oils Olive oil might be a go-to for cooking, but it isn't so great for seasoning a cast iron skillet. This is due to its lower smoking point, which is between 325 and 375 degrees Fahrenheit, according to World of Pans.
Highly Acidic Foods (Like Tomatoes)
The most common acidic food you might not want to cook in your cast-iron skillet is tomatoes.
Eggs fall into the category of sticky foods that are not ideal for cast iron skillets that haven't built up their seasoning yet. While cast iron can become non-stick with sufficient use over time, a newer skillet will almost certainly cause your eggs to stick to its porous surface.
If cast iron is left in the sink to soak, put in the dishwasher, or allowed to air dry, it will rust. It can also happen when you store your cookware in moisture-prone environments, such as a cabinet near a dishwasher, an open cabinet in a humid location, or stored outside.
Coconut, avocado, and lard (if using frequently) are the healthiest options, but almost any cooking oil will work.
You should only need to fully re-season your cast-iron cookware one to two times a year, but you may also want to give it some extra seasoning love anytime you cook something that requires a heavy-duty cleaning.
Vegetable oil is a common and affordable option for seasoning cast iron. It typically has a high smoke point (around 400°F) and is easy to find.
Best High Smoke Point Oils
Refined Avocado Oil - The smoke point of refined avocado oil is between 480 to 520 degrees Fahrenheit. Canola Oil - All canola oil is refined and has a smoke point between 400 and 475 degrees Fahrenheit. Grapeseed Oil - Grapeseed oil has a high smoke point of 420 degrees Fahrenheit.
The most stable vegetable oils include jojoba (actually a liquid wax), meadowfoam, fractionated coconut, watermelon seed, moringa and high oleic sunflower oils.
Once your pan is pre-heated, add a little oil or fat. Then simply add your food! (Note: if you want to use butter, start with oil, and then add butter right before you add your food.)
Although care must be taken in handling and processing of canola oil and other vegetable oils, canola oil is a safe and healthy form of fat that will reduce blood LDL cholesterol levels and heart disease risk compared to carbohydrates or saturated fats such as found in beef tallow or butter.
In many cases, you should avoid cooking acidic ingredients such as tomatoes, lemon juice, wine, and vinegar in your cast-iron skillet.
If you cooked something that stripped off a layer of seasoning on a part of your pan- you can run it through a few rounds of seasoning. You can't over-season cast iron so season as often as you'd like, but don't go crazy thinking you need to season your cast iron every Sunday.
Clean your cast-iron skillet each time you use it. Doing so prevents stuck-on food from staying on the skillet between uses. If the skillet is only slightly dirty, a quick wipe after cooking in it will work. If dirtier, or food is stuck, then scrubbing it is best.
You can use olive oil to season cast iron, but you need to choose a high quality extra virgin olive oil, which should have a smoke point close to 400 degrees Fahrenheit.
Bake your cookware upside down at 450 degrees Fahrenheit in the oven for one hour. Allow the pan to cool down completely, and repeat three more times.
Oil, especially canola oil (bad, unhealthy oil), should not be used. If a quick oiling (not seasoning) in between is desired, it's best to use a high temperature oil like avocado. A quick rub can do the trick, if your pan looks a bit dry. I have one pan that is about 100 years old!
The disadvantages of cast iron
One of the main drawbacks of cast iron pans is their weight. Cast iron is significantly heavier than other types of cookware, which can make handling and maneuvering them more challenging, especially for individuals with physical limitations.
The takeaway? It's safe to cook tomato- and wine-based sauces in cast iron, but you should save the vinegary pan sauces for stainless-steel pans—or dilute the vinegar (or citrus) with water or stock.
Cooking with a cast iron pan that has a little bit of surface rust on it isn't likely to hurt you. If your pan is seriously rusty or has visible rust flakes, you shouldn't cook with it until the rust is removed and the pan is washed and re-seasoned.