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How to Reseason Cast Iron (The Best Way Is Not What You Think!)

September 1, 2020

Why and How to Reseason Cast Iron

Have you ever wondered how to reseason a cast iron skillet or why we season cast iron at all? Maybe you want to get the best oil for curing cast iron, or maybe you don’t even know what seasoning a pan is? This post will explain pan seasoning, including the what, the why, and the how – including how to reseason cast iron and THE BEST oil to cure cast iron.

Seasoning or Reseasoning – What Is It?

Seasoning is about curing and sealing with oil. Some new pans come uneven and need seasoning before they are ready to use, but reseasoning is a kind of restoration. It is usually done to salvage a piece of cookware that is no longer cooking well. We fill and seal the inner cooking surface so that it is less porous.

Seasoning Cast Iron – What Is the Benefit?

Seasoning, or curing the pan, creates a smooth cooking surface that will last forever, if properly used. By building up the finish on the pan, a properly seasoned pan is smooth, slick, and uniform and resists developing rust. A seasoned pan is easy to wipe clean. A sealed surface means that today’s pancakes do not taste like last night’s garlic. The food does not stick, so you can relax and get a nice crispy sear on your tofu cubes. You save food, save time scrubbing, and save your health from chemical non-stick coatings. Food cooks evenly and consistently, require little to no oil, with little chance of ruining or burning food.

Reseasoning a Cast Iron Skillet – Why Do They Need It and When?

Over time, even a once smooth-surfaced pan can become sticky. If it did not have a great seasoning before, and you cook a lot of acidic foods, deglaze with wine, or scrub the pan with soap, it may become dull or rusty. If it gets heated when empty, it can become dry and porous, so it absorbs moisture from your food and the food sticks like crazy! If it is sticky or rusty or uneven, it requires reseasoning.

The Best Oil for Curing Cast Iron – and the Most Controversial!

It turns out, top quality flax oil is the best oil for seasoning a cast iron skillet.

Say what? Wouldn’t flax, the most heat-sensitive oil known, be the worst to use? People who care about healthy food preparation are probably confused: Flax oil can go in a skillet that will be heated to 500 degrees? Yes, it can – but we hear your gasps of horror and we know this statement may cause arguments to erupt on message boards between nutritionists and chefs.

Actually, it is precisely its heat sensitivity that allows flax oil to create a smooth, even and hard finish.

The Controversial Flax Oil Trick

Science explains that flax oil is the best oil for seasoning cast iron because it becomes polymerized by the heat. Chemistry-savvy folks understand that “polymerized” means that the molecules have re-arranged and linked together. Liquid oil can morph into a new solid state. This means it is not just moisturising the pan, but creating a solid, glassy material. A hard, slick surface.

Why Flax Oil?

This is what makes flaxseed oil unique. Only flax oil responds to heat this way, because it is less heat tolerant than other high smoke point fats. Using lard, tallow, shortening, avocado or coconut oil or any other seed or vegetable oil can create a sticky or peeling finish. You can find a chemistry-based blog post by Sheryl Canter with the science behind flax oil polymerization, and why that makes it ideal for seasoning a pan.

Seasoning Troubleshooting – How to Reseason a Cast Iron Pan

The seasoning on a pan can solve or even cause cast-iron complaints. Cast iron can be fabulous, but it is dependent on the seasoning. Bad seasoning does not last and is not very effective. This is why some folks don’t get the desired result.

  • It is easy to season badly by using too much oil applied all at once -solve this by using thin layers.
  • Too low a heat can make a pan sticky, so get it above 400 degrees.
  • Vegetable oils and animal fats are likely to leave a soft layer that wears unevenly, making the pan prone to scratching and hot spots. If it was seasoned with the wrong oil, the seasoning might start to scrape off, so be sure to use flax oil.

You Have Never Seasoned a Pan Like This Before!

Done right, flax oil helps you get the safest, slickest cast iron pots, pans and skillets while protecting your health. Let’s clear up the science behind the flax oil trick and explain how to clean and reseason cast iron using flax oil.

Flax oil + Cast iron pans = Safety

Unlike other non-stick pans, these pans are perfectly safe for your health, with none of the carcinogenic, teratogenic compounds found in chemically coated or treated surfaces in most commercial non-stick cookware. After the flax oil has polymerized the food just floats on top of it.

The Right Kind of Flaxseed Oil for Reseasoning Cast Iron

Other posts on using flax oil for reseasoning cast iron have been based on science, or on personal experience, but they were not written by flax oil experts, therefore please be sure to pay attention to these super important points about choosing the flax oil:

  • It is critical to use pure flax oil. It can be filtered, but it cannot be refined.
  • The oil must be free from additives. Do look for one ingredient – only flaxseed oil, 100% unadulterated. Do avoid additives used to prevent oxidation, such as vitamin E, rosemary extract, sage oleoresin, or any synthetic chemicals, as they can prevent the necessary polymerization from occurring. The oil must NOT be flavoured.
  • Avoid lignans. Even single ingredient flax oil could contain flax oil fibre called lignans, but this is no good for seasoning. This fiber has health benefits but can give the pan an uneven finish. Avoid any products mentioning “flaxseed particulate” or “lignans.” On Flora’s flax oils avoid the ones with a square on the front that says High Lignan.
  • Do choose certified organic and bottled in glass. Oils have a strong affinity for fat-soluble toxins, so if you are doing this process to avoid the dangerous chemicals in non-stick coatings, might as well steer clear of flax that has been dried using glyphosate or stored in xenoestrogen-laden plastic.
  • If you have an oil that meets all the above criteria, it is okay if it is past its prime. An oil that out-of-date and does not taste or smell fresh CAN still be used for seasoning cast iron.

The Reseasoning Process preparation – Before you Begin to reseason a cast iron pan

  1. Decide when to do the seasoning job. Preferably on a day where you can be outside in the yard or on the balcony for some of the day. Please note, you may want to be close by, and there is a chance your smoke detector will go off.
  2. Check that your oven can heat over 400 degrees, as 400-500 is the ideal window for seasoning. If not, or if you cannot imagine having the oven blasting in your house, perhaps you can use a large barbecue for the task.
  3. The job can involve some time spent oil buffing, minimum of 3 hours of hot oven time, and 6 hours of cooling time, depending how many coats you do.
  4. The pan surface will need a good cleaning – give it a good soaping, rinsing, and drying.
  5. If it is rough, go further and strip it.

Stripping A Pan – What Is It?

Before seasoning, old cast iron skillets, pots or pans might require the complete removal of outer layers prior to the sealing. This stripping or layer removal is done by scraping down and scrubbing with steel wool or if you have a self-cleaning oven feature, you could use that. In some cases, people employ oven cleaner, lye or other methods. How ever you do it, please be careful about fumes and refer to a professional source for advice. Luckily, once you do this method, you will likely never need to strip your pan again.

Restoring Cast Iron – How to Reseason a Cast Iron Skillet with Flax Oil

  1. Begin with a clean prepped pan on a day when you can open all the windows.
  2. Pour a teaspoon of flaxseed oil onto your hands, a fine cloth or paper towel.
  3. Rub it all over the inner surface of the pan. You want only a very, very thin layer of oil, so rub it in well. Make it look like it is no longer dry, but with no visible pooling, puddling, drips or wetness either, by removing extra oil with the cloth.
  4. Add more as needed to thinly cover the sides, bottom, and handle as well.
  5. Make sure the area is well-ventilated by turning on fans and opening windows.
  6. Place the skillet upside-down on a rack in the center of a cold oven.
  7. Set the oven to its highest temperature and let the pan and oven heat up.
  8. When the oven reaches its high temp, set a timer for one hour and exit the kitchen, since hot flax oil will smoke while it is burning off.
  9. After an hour, turn off the oven, and let cool with the door closed. Leave the pan to cool inside the oven, untouched, for an additional two hours.
  10. Remove and repeat: After two hours (three since you started), remove the pan from the oven. It should be cool, or warm at most. Once you can handle the pan with your bare hands, repeat the whole process (steps two through nine) at least once or twice more, but as many times as you like.

Cast Iron – is it Worth it?

Cast iron is very versatile, with excellent heat retention and dispersion properties at a range of temperatures. Vegetarians enjoy increasing their dietary iron using cast iron cookware. Many like serving a sizzling skillet meal hot from the stovetop or oven, and it works with all kinds – electric, gas, and induction. Outdoor enthusiasts love cast iron over grills, coals and campfires, or in brick, wood or even cob ovens. Green consumers like that these pots and pans have a virtually indestructible quality and never need replacing. It makes them a lifelong investment and an antidote to our disposable culture, reducing our environmental impact.

Cast Iron Complaints and Conclusions

When found at garage sales, pans are probably there because someone was tired of their food sticking. They may be rough, uneven, and even a little rusty. The Joy of Cooking complains that cast iron skillets rust and heat unevenly. This can be true but proper seasoning can solve these problems. These pans need restoring before they can be used for low-oil or oil-free sautéing.

Porous pans can be rusty, sticky, burn food and cause food to break. If they are not well-seasoned or broken in, frequently having to reseason the skillet can be a turnoff, as can needing to use a lot of oil to cook. We can all enjoy cast iron, but only if the pan is slippery enough, which means properly seasoned and broken in. Once you season a pan with several extremely thin coats of pure flax oil baked in at high heat, your pan will be a pleasure to use for years to come.

Flora is offering you a 15% savings on Certified Organic Flax Oil right now, simply apply the code HARVEST15 at checkout.


Dana Green Remedios, RHN, RNCP, is a Vancouver-based educator and coach. She is a regular contributor to the FloraHealthy blog and can answer your questions in English, French, and Spanish as a Product Information Specialist at Flora.

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