Cast-Iron Pots and Pans: Cleaning and Seasoning

Cast-iron cookware is wonderful. For some things, it's very hard to beat. You can run into problems with it, though, like rust (especially if it's been unused for years and/or got wet and wasn't dried out) and food sticks. Badly. Even with the new stuff.

Are there fixes for this? I'm glad you asked.

Old Stuff
I went to a local flea market Saturday, and picked up this cast-iron pot for $5.

Yes, it's rusty inside and out, but it has some important features:

1. No cracks. 
2. No deep pits from the rust. There are some small ones, but the rest is all surface stuff that'll come off fairly easily. 
3. For five bucks, who wants to pass that up? 

Cleanup
Every bit of this can be done with hand-powered tools: a wire brush or two and sandpaper or sanding blocks. Being both lazy and having some joints not up to that, I'm going to use power.

This is a buffer from Harbor Freight (not a Baldor, but it didn't cost a few hundred dollars, either) with a wire wheel brush on one side. That'll strip the surface rust off the outside in just a few minutes.

Some safety notes:

• If you put a wire wheel on a grinder or buffer, be warned that if you get careless it'll take the skin - and maybe some tissue - off you just as fast as it takes rust off. 
•  Wear goggles or something, as sometimes a wire will break loose and fly off. 
• A dust mask might be a good idea, too; it's only iron oxide you're brushing off, but you probably don't want to inhale the stuff.

Once the outside is done, the inside gets the treatment with this, a ball-shaped wire brush on the drill. Depending on your drill, you might add some earplugs or muffs to the above-noted safety stuff, as some drills are pretty loud.

For the inside, brush/blow all the loose stuff out that you can, then start brushing with this. Work it over the entire inside surface, dump/blow out all the loose stuff, and repeat a few times. That'll get rid of all the rust, and let you see if the surface needs more work.

In this case, there's no nasty pitting, but the inside has the as-cast texture and a bit of roughness from the rust, and I want it smoother. For that I've got this, a sanding disc attachment for the drill. 

 This one uses stick-on abrasive pads, which you can get from 60 grit (coarse) to fine in the 200's (depending on brand). In this case, I started with a 60.

The disc is flexible, so it's not hard to work it into the curve at the base, then up the sides. Once you've got a fair amount of dust/rust/iron loose, dump it and keep going. When it's as smooth as you want/can get, clean it out and go to a finer disc. In the case of a frying pan, where you want it really smooth, a 220-240 grit finish is plenty fine; in this case I stopped at 150, partly because that's the last disc I had (need to keep some more in the shop).

You don't have to be perfectionist on this, but the fact is that the smoother the cooking surface, the easier it is to clean out later. I'll probably go back later with some 180 and 220 to really smooth it out, but for a stewpot this should be fine.

Now wash it. REALLY wash it, with good soap and a scrub brush, to be sure you get any traces of old grease, sanding dust and rust off, inside and out.

 
Much better.

Seasoning
There are a number of ways people say to season cookware, so this isn't The Only Way. It does work, so I'm going with it:

1. Wash it inside and out. REALLY wash it, water and soap and a scrub brush, get all the loose rust and iron dust and abrasive dust out and off. 
2. Dry the pot, and stick it in the oven for about ten minutes at low, or 100F or so if you can set it exactly, to dry it completely and get it warm.
3. Then comes the seasoning: lard, bacon grease or tallow*. Give the outside a light coat, then give the inside a heavy coat, all the way around, bottom and sides. 
4. Put it on some aluminum foil or a cookie sheet or something to catch any runoff, and back into the oven, then turn it up to 250F.
5. Leave it at least fifteen minutes, then take it out and swab the sides again to make sure they're coated, then back in. 
6.  Repeat twice more (no particular reason, I just think that number works), then turn off the oven and let it cool completely. 
7. Take it out and wipe off the excess (and if you used enough, there will be excess). The heating opens up the surface of the iron a bit, and keeps the grease hot so it can get into the surface.

That's it.

Now I need to plan some stew or beans or something to try it out.

New Cast-Iron
A lot of new cast-iron stuff is marked 'pre-seasoned'. Mostly that's a lie, partly because the inside is not fully finished; it has that pebbly texture from the casting process. At the very least, you need to scrub the hell out of it to remove the 'pre-seasoning' stuff (protectant put on to keep it from rusting during shipping off) and then season it.

Want to really do it right? Get the sanding disc setup and use it to cut that finish down smooth, then season it.

Cleaning After Seasoning (old and new)
With good skillets, it's not unusual to do nothing more than wipe it out with a paper towel, but occasionally you may need to wash one out. Yes, you can use water. Yes, you can use a brush. What you can't use is soap; it'll strip out the seasoning. 

My usual process is: 

1. Pour some hot -- really hot, not just warm -- water in.
2. Use a brush to work it around the inside, dump that, then rinse with hot water. 
3. Put it on the stove, or in the oven, on low for a while to dry it thoroughly
4. Done. 

My daughter likes to do this for a frying pan:

1. Put some water in.
2. Put it on a burner.
3. Let it get hot.
4. Brush it out.
5. Rinse and dry. 

Works great.

And don't be afraid of using a brush. One of the 'Used by Professional Chefs!' things for cast iron is a square or pad of mail armor made with stainless steel wire like this; if this won't damage things, a scrub brush won't.

Note: I'm told these scrubbers will not only clean everything off the surface, but will remove skin nicely if you don't use gloves.

More on Seasoning
You can start arguments asking about this. I've been using the oven-and-suitable-grease method for quite a while. You can also use vegetable oil if you'd prefer. I ran across this a while back from Matfer Bourgeat, who make what are supposed to be very good carbon-steel skillets:

1. Before use, wash pan under hot water in mild detergent, use a bristle brush to scrub all protective coating, proceed by thoroughly drying pan.
2. Place in pan the following ingredients and sauté on medium heat while swirling around entire pan. Amount of ingredient will vary depending the size of pan i.e. medium pan use 1/3-cup oil, 2/3-cup salt, & 2 whole potato peelings. Discard after sautéing for 10 minutes.
3. Repeat step 2 again.
4. After processing steps 2 & 3 use oil with paper towel and wipe entire pan.

I saw this on a cooking show. They mentioned they'd never heard this method before, but it worked very well.

*Tallow is from beef, as lard is from pig