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Nerdy Science in the Kitchen

How to Season Cast Iron With Flaxseed Oil



black cast iron skillet seasoned with flaxseed oil with sausages
Season your cast iron with flaxseed oil for great-tasting results.

In the past few years, rumors of excellent cast iron seasons using flaxseed oil have caught our ears, and we were anxious to try it out.

If you have not yet tried to totally strip and re-season a piece of cast iron, please consider the process…and check out this other post to provide some context about the process, benefits, and why one may consider stripping the existing seasoning.

If you’re just interested in seasoning or re-seasoning your cast iron and you don’t have any flaxseed oil handy, check out the post using any old oil you have around.

Flax Oil: This guy cost $9 at the grocery store!
This guy cost $9 at the grocery store!

What the heck is a flax?

Great question. Flax is a flowering plant (the blooms are blue) that grows in the cooler part of the Northwestern United States and Western Canada. Flaxseed oil contains a high percentage of omega-3 fatty acids – we’re talking 8 grams per tablespoon.

I know you won’t get all that tasty omega-3 fatty acid from seasoning your cast iron but you can use the rest as a dietary supplement. These are the same heart-healthy fatty acids promoted by cardiologists and dietitians found in fish and nuts (and flax seed).

Interestingly, these same fatty acids apparently provide an extremely tough and slick seasoning layer when they polymerize to form the seasoning layer on the surface of cast iron. I normally put a little flaxseed oil in my smoothies (~1 tablespoon in 20 oz) and the oil has a mild nutty flavor and when it is mixed in a smoothie, it works well with bananas and soy milk.

The upshot of this is that you can find flaxseed oil pretty easily in the health-food section of your local megamart. The downside is that flaxseed oil has a distinct “fishy” smell to it due to the presence of these omega-3 fats.

No worries, once polymerized by the heat, the oil will form a smooth, non-reactive surface and the fishy smell will disappear. “How fishy?” you may be asking yourself.

It’s pretty darn fishy, so prepare your significant other accordingly. You might consider doing this on the grill if you have a command of temperature control or you have some hot coals smoldering from grilling some meat.


How to Season Cast Iron With Flaxseed Oil

Nature's Way Organic Flax Oil Super Lignan 24 Ounce

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This is our favorite flaxseed oil to use to season cast iron!

There are many guides on how to season cast iron cookware. Below is the method we chose to use here, taken from a Cook’s Illustrated article on this subject:

  1. Preheat oven to 200 degrees Fahrenheit. Once preheated, place cookware into oven for 15 minutes. [The important part here is to ensure the cast iron is dry and slightly warm which helps the metal take up the oil.]
  2. Remove cookware from oven, turn oven off, and open the door to let it cool down as much as possible.
  3. Place ~1 tablespoon of oil into the hot cookware and wipe it around with a wad of paper towel. Be sure to get every nook and cranny, inside and outside. Using a second paper towel, wipe as much excess oil off of the surface as possible.
  4. Put the cookware upside down into the (semi) cool oven. Turn the oven to “Bake” at its hottest setting (usually 500 or 550 degrees Fahrenheit). Once the oven reaches this temperature, leave the cookware inside for 1 hour.
  5. After 1 hour, turn the oven off and let cool completely with the cookware inside.
  6. Repeat Steps 1-5 at least 5 times, or until a smooth, black season is obtained.

Cast Iron Skillet Seasoned with Flax Seed Oil

As you can see, there’s not much to it, but unfortunately, a lot of waiting around is involved. Luckily, after the first coat is applied, the danger of rust is past and you can apply the other coats over a few days.

You might like my post on restoring cast iron tools.

If you can only afford the time to apply just one coating, well, that’s good too. Just start cooking on the cookware and you’ll be well on your way to having some very nicely seasoned cast iron cookware. The more you use it, the better!

The resulting flaxseed seasoning probably won’t be any more slick than another, but the hype is that it’s much tougher than other seasonings.

Image: Photo by Milan from Pexels

Kitchen Professor author
About the Author: Rose Reinhard

Rose Reinhard is a Thai-American foodie from Chiang Mai, Thailand. She's been a creative writer since she could speak and enjoys making vegetarian/vegan dishes and reading about food science. She claims her air-fryer is the best purchase she’s ever made to date.

18 thoughts on “How to Season Cast Iron With Flaxseed Oil”

  1. I also use flaxseed, but read that it can flake off in time. So I switched to lard. The lard always left a very dull finish. I switched back to flaxseed and havnt had any problems.

    • Hey Neal, thanks for the comment! Interesting about the lard. I haven’t tried that myself. The flaxseed has served me well so far!

    • I seasoned my Lodge skillet once with Crisco, then a few months later, gave organic flax oil a try. I didn’t have any problems with the seasoning. :)

      • Every year, I reseason my cast iron cookware and bakeware. I have always used Crisco. I do follow the seasoning process as described above.

        I am the 4th generation to use some of these pieces and all of them look fantastic after years of service. It’s hard to figure out which ones are the antiques and which ones are modern…….

  2. I’ve read that cast iron should be seasoned after every use. Not to this extent, but simply just cleaning it, then wiping it down with the oil of choice. Is flaxseed oil used for this or is it only for completely re seasoning the cast iron?

    • Hi Peter, You are exactly right. So some people say “season after every use” when they mean wash and lightly reapply oil. That keeps the cast iron from rusting.

      I usually just put a little bit of oil (1/2 tsp) on a paper towel and coat the piece. You can also spray a tiny bit of cooking spray (like Pam), then wipe it around.

      • So just to be clear, when you apply oil after every use you aren’t too picky about what you use, but when you take the time to truly season it you use flaxseed oil? I can just see it being somewhat expensive if you use flaxseed to reapply every time if you use it a lot. I was thinking about seasoning with flax, then after each use using some other type of oil.

        • That’s right, Peter. Good clarification. I’ll use just about any oil for daily use. I’ve only used the flaxseed oil 2x or so.

          I put the flaxseed oil in my smoothies for a few weeks – for Omega 3 fatty acids – which are apparently good for you!

          Let me know how it turns out if you try it.

      • Doug, from personal experience (and various cast iron web sites), cooking spray is a very, very bad idea. It leaves a sticky residue that will build up over time into a nasty gunk, and then you have to strip and re-season all over again.

        I scrub the cast iron in hot water, wipe dry, place on a burner on low heat, and when it’s thoroughly dry, wipe bacon grease, unrendered leaf lard, or solid coconut oil onto the warm pan. Then I turn up the heat a little and let it heat until the oil is smoking. Turn off heat and let cool, then wipe off any excess and store it away.

        Works for me.

  3. Not the best oil to use….there are much better choices……this is is an old study and has been disproved by many cast iron groups…..

    • Interesting comment, but pointless without some sort of reference to back it up. Any websites, or forums, or anything that can lend credence to this claim? Can you or anybody reading these comments provide a reference to help validate this claim?

      • RJ, I’ve done some research, and the main claims I see about flaxseed not being a good oil to use to season cast iron is from individuals on Reddit. Most of the research claims that flaxseed oil is still the best way to season cast iron, although it is a lengthy and time-consuming process.

    • These oils are known as drying oils and when they cure leave a fairly hard finish on wood. Linseed oil is what I have used on furniture and tung oil as well. I used the Crisco method for years (thank you Alton Brown) but have switched to flax seed oil and there is a big difference. These is a site that actually goes through the process of drying oils polymerizing and their use in cast iron, if I can find it I’ll post it here.

  4. First, thanks for the info.
    Now, for the unsolicited lecture on grievous 21st-century hyphen abuse…

    This construction takes no hyphen:
    Set the oven to 500 degrees.
    This one, in which “500” and “degree” are combined to form a compound adjective, does take a hyphen:
    Put the skillet into a 500-degree oven.


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