Restoring Cast Iron

I’m pleased to present a guest post from Chris Maddox. We were both commenting on a thread about reseasoning cast iron, and he mentioned restoration. I happily begged for a guest post and he obliged. Cast iron is a topic I’ve covered before, and I’m happy to get back to it. I grew up cooking with it, I taught my kids to cook on it, and I can hopefully pass that joy onto others who will understand the beauty of the material in making really good food. 

Restoring Old Cast Iron Pans

Before I begin, I want to thank Cedar for the opportunity, she’s a great encourager to a lot of us out here.  Second, I want to apologize for no pictures.  This was not something I originally intended to write anything about.  There are a gagillion articles out there on this subject, but after reflection came to the conclusion that if you’re like me, you look at many of those articles with a gimlet eye.   If “a friend of a friend” has some experience in a topic, I’ll be more inclined to follow their experience.   So here goes.

Ah, there it is…the old cast iron pan your grandmother used to cook eggs and bacon when you spent the weekend with her all those years agone.  Unforturnately, the shiny black surface that was the evidence of the love and lard Grams cooked with has turned red and pitted with rust and neglect.

How to you get all that off and restore this once beloved piece of cookware to usable condition?  The short answer is “strip it down to bare metal and begin again.”  In order to do this, you have 4 basic options:   1.) Manual Labor– This is the simplest procedure but the most amount of work.   Steel wool and elbow grease. (And if you want to use the pan this century, you might want to consider another option. )  2.) Mechanical– Drill and wire brush.  This is probably the fastest method, but you really need a good power drill for this;  a corded drill.  You’re likely not going to create the amount of RPM and torque with a battery operated drill, you’re going to need wall juice for this option.  3.)Chemical-this is the method we’re going to talk about in this article.  Using chemical reactions to dissolve the seasoning and rust so that the pan can be cleaned up in a short period of time than method 1 and with a little less effort.  And 4.)Electrolysis – You can dissolve both seasoning and rust by using a 12V car battery charger and a baking soda solution.  But it’s a little complex (and I haven’t actually tried it yet, so I’ll cover it in another article)

In restoring the pan, you’ve got two challenges.  First, you need to remove the old seasoning.  It’s that black coating on a cast iron pan.  It’s (sometimes) years of burnt lard, bacon grease, oils, etc.   layered into the pan creating that “nonstick” coating we all want.   However, in this case it’s a barrier to what you want to accomplish, which is stripping the pan down to bare cast iron.   Then you need to remove the rust.  Both are related and so different in their approach.  Short of taking the wire brush or using a more technical approach like electrolysis , you’re about to embark on a several day process.  This pan didn’t get in its current condition overnight, so fixing it won’t either.  But fear not, fixing it doesn’t have to take a long period of time; just a few days and little effort.

Let’s start by taking off the old seasoning.

Trying to restore a couple of old cast iron pieces I have, I’ve tried a couple of different methods.   If you google it, there are literally hundreds, if not thousands of articles and you-tubes.

All of the articles I’ve read on this subject pretty much boil down to one particular compound to successfully strip the  old seasoning off:   Lye, or Sodium Hydroxide (NaOH for you chemistry nerds)  is an alkali solution that positively EATS the old seasoning off the cast iron without eating away at the metal.  There are several different ways to get lye.

You can purchase it in bulk online or from a hardware store.    Lye is used in certain drain “clog busters” like Drano.

You have to cautious with drain cleaners.   Lye isn’t always the ONLY ingredient, some use sulphuric acid or some other chemical that makes it not so nice to work with so I decided to leave them alone.   I just want to cook on cast iron, not look at multiple MSDS (material safety data sheets).

The best place to find lye for our purposes is found in…wait for it…oven cleaner.   That stuff you spray on the inside of your oven (if you don’t tend to use the self-clean feature) has lye in it and just as it cleans the inside of your oven, it does the same thing to old seasoning on cast iron.  There’s the added plus that we don’t have to worry about all the other potentially “bad” chemicals that could be in the drain cleaner and comes in a handy dandy delivery system.

So now, all we have to do is gather our materials and get to work.

Deseasoning the Skillet

• 1 Can of Oven Cleaner containing Lye (Sodium Hidroxide NaOH)
• Rubber Gloves  and goggles.   Lye is an alkali chemical.  It CAN seminasty things to happen…like burns, so wear protective gear like googles (those little orbs in your eyesockets…they are pretty important…protect them) and rubber (the type you buy for dishwashing is great but latex or vinyl exam or food service gloves will work).
• Closable container or trashbag.
• Scotchbright pads or steel wood pads
• Wire brush (about the size of a toothbrush for getting in crevices and handle holes. )

Spray the skillet with oven cleaner.   Some of the articles I’ve read argued, “just worry about the cooking surface,” but to tell the truth, you don’t want ANY left overs on the skillet.   It will be easier in the long run to tell you’ve gotten the job done when the skillet is completely down to bare metal.  Get it well covered, but don’t go hog wild. You may have to do another application anyway.

Place the skillet in container or trashbag and close it up.   Let the lye do its job.   I let my skillet sit for 24 hours at the minimum.  Heat tends to help with the chemical reactions, so leaving your project out in the sunlight helps.

Once the lye has had time to “eat” at the seasoning, now the “work” starts.   Put your gloves and goggles back on.  Take your skillet and a scotchbrite pad or some steel wool and head to the sink.  I used the big laundry sink in my garage, but a kitchen sink is fine—just be sure to warn the “owner” of your kitchen.   It’s about to get dirty in that sink.

Start scrubbing.   The lye will dissolve the old seasoning so that you really don’t have to work very hard to get it off.  Depending on the thickness of the seasoning, you may have to apply the cleaner another time after you get the initial layers off.  I didn’t have to, but if you still see black specks and remains of old seasoning, I would go ahead and do it.

After you get all of the seasoning off, all you should be left with is a skillet with some surface rust on it.   Depending on the age of the skillet and how long it’s been neglected it may be a little or a significant amount.  NOTE:   Too long and the rust may really pit the cooking surface.   Once you get the rust dissolved as we’ll talk about in a minute, you may have to take extra steps to make the cooking surface smooth again.  Trust me.  You want the cooking surface as smooth as possible.

Derusting the skillet:

• Gloves and Goggles
• 5 gallon bucket or similar container and lid
• 5 gallons of white distilled vinegar—about 2.50 / gallon at Walmart
• Steel wool or scotchbrite.
• Wire brush (about the size of a toothbrush for getting in crevices and handle holes. )

Once you’ve gotten all of the seasoning off.   The rust is now the only thing standing between you and that seasoning that skillet so that you can enjoy the bacony goodness of cast iron cooking.

Wash and dry the skillet with warm water and soap to get all of the traces of lye off the skillet.

Now place your skillet in a bucket or other container big enough to house the skillet still be able to close it off.   I tried several containers and the one I found that worked best was a five gallon bucket (you can buy these at most Walmarts, a hardware store or Lowe’s/Home Depot—they’re about 3-5 dollars.)  If you are working with more than 1, a plastic tote bin will work.

Cover the skillet COMPLETELY with vinegar.  I used white vinegar because you can buy it by the gallon cheaply.  You should almost immediately start to see bubbles.  This is the acid in the vinegar reacting to the iron oxide of the rust.   This is a good thing.  Close up the container and if possible put it out in the sun where it can get warm.  The slight heat will speed up the process.

Let it sit for 24 to 48 hours depending on the amount of rust.   Again, let the chemicals do the work for you.  The longer you let it sit, the more it’s going to eat at the rust.

When you pull the skillet out of the container, the rust should have turned blackish.   Now we’re back to the sink and the scrubbing.  Be of good cheer , however because if the vinegar has done its job, the rust should come right off the metal.  Cast Iron without all the rust and seasoning should be a light to middark shade of grey.   Now you should be able to gauge how pitted and damaged the cooking surface has become.   If it’s too pitted, you’re going to have to sand it down to restore the smooth finish (this is one of the risks involved with the wire brush approach as well.   You use the brush…you’re going to have to sand it smooth again.)

The heavier the pitting on the skillet, the rougher the sandpaper you’re going to need.   The metal oxide paper found down the automotive paint aisle at Walmart will do fine.   The sandpaper gets finer as you go UP in grit…so a 200 grit is a finer grit than 100 and will polish better.   For finish sanding you want 300 grit or better.

Get that skillet smooth and you’re ready to reseason.   Cedar has a wonderful article on reseasoning cast iron.   Check it out.   My next article I’ll detail how my experiment in electrolysis went.

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