31 July 2013

How to Barbecue a Pot

I've been barbecuing a pot. No, not pot - we're not talking about marijuana shishkabobs - but a pot. A cast iron casserole, to be precise.

I found it at the second-hand store when I was on a quest for a pot to use for camping. Brilliant, I thinks - cast iron can go right into the campfire, that's perfect! So I grabbed it, paid my $12.99 (that's a decent deal for a cast iron pot, even an unprepossessing no-name one like this - it's not a Lodge, let alone Griswold, but it's cast iron), and triumphantly bore it home. But when I took a closer look at the thing, it turned out to have been previously owned by someone of the never-wash-cast-iron-it'll-ruin-it persuasion, which, of course, ruined it. It had a layer of black crud all around the inside of the pot and the lid, some of it almost 2mm thick. Not pretty. I think anything cooked in that pot would have had a nice seasoning of black flaky who-knows-what mixed in.

For starters, I tried soaking it in water, which, needless to say, didn't do much at all. Oh yes, some of the crud flaked off, exposing bare iron underneath, which promptly started rusting. (That's exactly what would have happened if I had cooked, say, chili in it. Yummy.) So now I had a crud-covered pot with rust spots interspersed with the black bumpy layer of baked-on whatever-it-was.

Discouraged yet? Well, I wasn't. You see, long before I bought that pot, I had read up on this stuff online. Cast iron is almost indestructible. You know your cast iron pot is ruined when - well, maybe when it's got a hole in it. The kind you can see daylight through, when the pot literally falls apart. Otherwise, you can fix it. So that's what I proceeded to do, according to the instructions on the websites I found.

The first step was oven cleaner. Yes, the really harsh, stinky, spray-on kind, that makes you cough and gag while using it. Yuck. I took the pot and a big garbage bag, sat the pot inside the bag, put everything together into a cardboard box, took it out into the driveway, suited myself up in long pants, long-sleeved shirt and rubber gloves (I just about had a heat stroke), and sprayed down the whole pot and lid, inside and out, with the oven cleaner [cough, hack]. Then I closed the bag, shut the lid on the box, and put it up high out of reach of the cats. The point of the bagging is to keep the oven cleaner from evaporating, so it can work longer (the point of the closed box is cat protection).

I left the whole thing sitting for about 18 hours. Longer would have been better, but I'm impatient, so I suited up in my chemical hazard gear again and brought the whole box in to the kitchen sink. When I took the pot out of the bag, a lot of the buildup had turned from hard, crusty crud into black, goopy crud that just washed right off the pot. Now, it would have been better to have given it another coat of oven cleaner and put it back in the bag for another day to dissolve the remaining crud, but, well, did I mention I'm impatient? So I tackled the rest of it with elbow grease and a stainless steel scrubby pad. I got pretty much all of it off by the sweat of my brow. (Literally, I had sweat pouring down my face. Long-sleeved sweaters aren't the most congenial items of clothing for the kind of weather we had yesterday).

So now I had a crud-free pot, stripped down to the bare grey iron, which immediately developed a coating of rust all over it. I knew that would happen - no big deal. Those websites about how to recondition cast iron have various suggestions for what to do about the rust, but I found just giving it a good wash in very hot water and then drying it right away took most of it off.

And then came the barbecuing part. Well, first the oil. You'll find various suggestions for which fats are most suitable for seasoning cast iron (lard is the most traditional choice), but I followed the advice of Sheryl Canter on this website, who recommends using unrefined flaxseed oil for the purpose. As an occasional oil painter, her reasoning makes heaps of sense to me - flaxseed or linseed oil is a drying oil, which actually means not "drying" as in "water evaporation", but solidifying by polymerisation. Linseed-oil-based paintings have a very hard surface, once they're fully cured. See, that's also the nonsense behind the "don't wash cast iron with soap" idea: cast iron seasoning is oil, goes the reasoning, and soap dissolves oil, so ergo, no soap on cast iron. But by the time the oil is bonded with carbon onto the iron, it's not ordinary oil any longer that can just be washed off with soap - just like you can clean an oil painting with soapy water without doing any damage to it, or scrub your kitchen walls, which might be painted with oil-based paints, as much as you like. To be fair, the idea of "no soap on cast iron" probably originated in the days when soap was homemade and possibly had a surfeit of lye in it (if the soap recipe or procedure wasn't quite right - but that's another blog post), and lye, as the oven cleaner process shows, does strip cast iron down to its bare metal.

So I rubbed the clean, very slightly rusty pot all over with linseed oil. And then I rubbed most of it off again. You want a thin layer - many thin layers, not one thick one. (Once again, look to oil painting - the thick blobs take forever to cure and always stay blobby, which is one of the advantages of oils to painting, but not to cast-iron-curing.) And THEN (yes, I did eventually come to that) I stuck it on the barbecue. Upside down, the lid leaning up against it. And lit the BBQ, let it get to about 500ºF (260ºC) and let the pot cook for an hour.

It would, of course, be possible to do this in the kitchen oven. But for one, it was a hot day, and the last thing I needed was for my kitchen to get any hotter (30ºC is more than enough, thank you). But more importantly, the point of seasoning cast iron is that you need to get past the smoke point of the oil; in a sense, you're burning the oil onto the iron. So by its very definition, this process generates smoke. In fact, between the burger drippings burning off the barbecue, and the oil from the pot, it generated enough smoke coming in through the windows to set off my smoke alarm inside the house. (I closed the windows after that.)

Then I turned the barbecue off, let the pot cool a bit, gave it another layer of oil, and repeated the process (there was far less smoke by then, without the burger drippings). Ideally, the pot should have about six coats, but, well, I did mention I'm impatient, didn't I? So it's just got two coats so far. I might give it a few more later. But even as is, it's got a beautiful, even black sheen, just like any pre-seasoned cast iron pot you get from the store. It's a thing of beauty and a joy forever. Well, for a while, anyway, until I cook enough tomato-sauce based dishes in it to strip the seasoning again. Rubbing a thin layer of oil back onto the pot after cleaning it helps with that.

So there you have it. Life, the Universe, and a Barbecued Cast Iron Pot. I'm quite proud of it.

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