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How To: Seasoning Cast Iron
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DrBiggles



Joined: 12 May 2005
Posts: 355
Location: Richmond, CA

PostPosted: Fri Feb 16, 2007 2:22 am    Post subject: Reply with quote

watt wrote:
I'm not so sure this 'carbon layer' idea is right. I've used (and continue to use) cast iron ware for many years. I've never used the high temperature method, and never had any problems.

The pan develops a patina over several months of use with ordinary veg oil. Washing is done soon after cooking stops (and while there is still heat in the pan) in warm soapy water, then thoroughly rinsed and dried. If warm clean water is put into the pan, an oily film appears on it. This suggestes to me that the 'seasoning' is either just veg oil or fatty acids that have reacted with the iron, similar to saponification of FA in the manufacture of soap. That is, over time, a layer of fatty acids is formed; the FA stick to the iron by chemically bonding (the iron replaces the glycerol backbone in fats/oils.

I can't see why a carbon layer would be non-stick, or even stick to iron, unless it formed a bond, forming steel, but this must be at a much higher temperature, as in forging.

One last thing, never get salt anywhere near cast iron, so butter (salted kinds) would not be suitable, neither is the use of Kosher salt (sea salt) to smooth the surface of the iron recommended for the same reason; significant corrosion. Another good reason to wait to the end of cooking before adding salt to a dish Wink
just thoughts
watt


Our First Volley:


Quote him this : "I can't see why a carbon layer would be non-stick"
and then ask him if he has ever heard of graphite, the most
energetically favored crystalline form of carbon. Even diamonds if
heated will turn into graphite. Not much sticks to graphite, perhaps
he is aware of this lubricious property?

Can he see now how a "carbon" layer might crystallize into graphite
and become nonstick carbon?

Or, as we say in Russian, can he find his ass with both hands and a hunting dog?

Next?
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watt
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PostPosted: Fri Feb 16, 2007 6:56 am    Post subject: Reply with quote

yes to the last insult.


you seem to have a complete lack of knowledge of basic chemistry, Dr.B.

Graphite can be used as a lubricant, but it is mined in the form it is used, not formed from anything else, and certainly not diamond, which would just burn (in air) if heated sufficiently. Though both are put up as forms of pure carbon, each is covered at their extremities with hydrogen. Only fullerene (AFAIK) could be called pure carbon. And where did you get the idea that graphite is crystalline?

Now come up with a plausible scientific answer, how about an oxide layer forming on the iron?

just thoughts
watt
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Fri Feb 16, 2007 3:57 pm    Post subject: Reply with quote

Iron oxides:

Iron(II) oxide or ferrous oxide (FeO): The black-coloured powder in particular can cause explosions as it readily ignites.

Iron(III) oxide or ferric oxide (Fe2O3): known in its natural state as rouge or hematite (also 'haematite'), but also purified for use as a coating in magnetic audio and computer media, where it is known as ferric oxide. In a dry or alkaline environment it can cause passivation and inhibits rust. It is also a component of rust. THIS IS THE OXIDE THAT FORMS ON POORLY CARED FOR CAST IRON PANS.

Iron(II,III) oxide or ferrous ferric oxide (Fe3O4): better known as the black-coloured mineral magnetite or lodestone also seen on Mars. Also a main source of iron, magnetite is an iron ore. This form of iron oxide tends to occur when iron corrodes underwater, and so is often found inside tanks or below the waterline of ships.
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WATT
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PostPosted: Fri Feb 23, 2007 9:29 pm    Post subject: Reply with quote

very good, Gary. Its the magnetite which is interesting. A coating of this (by oxidation using water) is used to inhibit corrosion in pressurised water nuclear reactors. It has the advantage of having the same lattice size as pure iron, and therefore does not expand and form flakes, as rust does. Magnetite is very useful. It is what I was thinking about when I said the blackening on cast iron may be due to oxidation (it also works on stainless steel)

What dya think?

watt
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Sat Feb 24, 2007 4:13 am    Post subject: Reply with quote

I am not an expert on iron oxides. I only know what I read, and while magnetite may be the oxide that makes the cast iron pans black, in contrast to pale gray--the "as cast" color after phosphate, gypsum or sand investment has been sandblasted and cleaned off, I really have no idea. You may have stumbled on something though.
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Javaman



Joined: 09 Mar 2007
Posts: 4

PostPosted: Fri Mar 09, 2007 3:53 pm    Post subject: Reply with quote

I'm a bit skeptical that pushing the fat to carbon does anything useful in getting a nonstick surface. Since deep frying stuff (at around 300-375degs) is well known to be one of the best ways to get decent seasoning, why would excessive heat above and beyond the smoke point work better?
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DrBiggles



Joined: 12 May 2005
Posts: 355
Location: Richmond, CA

PostPosted: Fri Mar 09, 2007 10:00 pm    Post subject: Reply with quote

Javaman wrote:
I'm a bit skeptical that pushing the fat to carbon does anything useful in getting a nonstick surface. Since deep frying stuff (at around 300-375degs) is well known to be one of the best ways to get decent seasoning, why would excessive heat above and beyond the smoke point work better?


Dunno, but the pans sure as heck like it. I pan seared a pieced out stewing chicken (thick fatty skin) earlier this week. To get the pan hot, I let it sit on high heat until most of the shiny seasoning had burned away. This means it was exceptionally hot. Swirled in 3 laps of cooking oil, looked as though it might ignite it was so hot. Then carefully laid in the chicken, skin side down.

When the pan was cool, washed and it was remarkable at how much nicer the patina had become. Even, shiny, glossy, film over all.

I started doing it about 15 years ago when I was doing the same heat for making tortillas. After a while the griddle looked as though I'd had it for 50 years. Even 15 years later that same seasoning is still beautiful and works just like it should.

Biggles
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PostPosted: Sun May 06, 2007 3:56 pm    Post subject: Reply with quote

Javaman wrote:
I'm a bit skeptical that pushing the fat to carbon does anything useful in getting a nonstick surface. Since deep frying stuff (at around 300-375degs) is well known to be one of the best ways to get decent seasoning, why would excessive heat above and beyond the smoke point work better?


I think that the (now ancient) original post by Jörg was a good one, and was certainly provocative, but nonetheless misleading on one point. It' isn't the carbon alone that creates seasoning's non-stick properties but the polymerization of the fat that results in a plastic finish which, together with the carbonization, protects the iron from rust, reduces acid reactivity, and is comparatively non-stick. Fat which is only polymerized remains a bit sticky and is pretty easily removed. Carbonization occurs only above the smoke point and results in the desired hard, black finish.

In Alton Brown's article on cleaning techniques in "Food and Wine," he suggests that an actual bond with the metal occurs. About this, I'm unsure. <http://www.foodandwine.com/articles/mr.-clean-|-alton-brown>
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Guest






PostPosted: Mon Jun 25, 2007 3:44 am    Post subject: Grapeseed oil Reply with quote

Well I tried the grapeseed oil technique.

I poured some grapeseed oil inside the pan, then used a paper towel to spread it around the rest of the pan (bottom, handle, and sides), baked at 400 F for 45 minutes, spread another layer on and baked at 450 for 45 minutes and 500 for 45 minutes (since I've seen the smokepoint of the oil varied here between 420-485 F).

What turned out was mostly perfect. The inside of the pan was as smooth as could be (not gummy anywhere) but also appeared somewhat striated. To explain, it looked as if some of it had carbonized at different rates in little pools or bubbles, but being that I put it on the rack upside down, this could not be the case. The rims of the pan, on the other hand, appeared almost powder coated in some spots and had raised areas of carbonization. These were easily scraped off with a thumbnail and revealed what looks like *rust* on the underside of these raised areas. This, too, came off with a fingernail, but it certainly looks a lot like rust.

I have decided that I will put more oil on the inside and the rim and try this again at no more than 450 F. Perhaps it carbonized too quickly at 500 F, causing the striation and raised spots.
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skjessen
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PostPosted: Fri Jun 29, 2007 7:39 am    Post subject: Cast Iron pots Reply with quote

Uh oh I'm out of my league. I just bought some ironware at a yard sale. My Southern grandma had some and I wanted to adopt a little of my southern heritage Most of the pots looked good but one of them had alot of black build-up on the outside of the pan. I used steel wool, Brillo pads, my Dremel and finally a kitchen knife. Have I made a mistake reading this forum makes me think so.
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Fri Jun 29, 2007 1:17 pm    Post subject: Re: Cast Iron pots Reply with quote

skjessen wrote:
Uh oh I'm out of my league. I just bought some ironware at a yard sale. My Southern grandma had some and I wanted to adopt a little of my southern heritage Most of the pots looked good but one of them had alot of black build-up on the outside of the pan. I used steel wool, Brillo pads, my Dremel and finally a kitchen knife. Have I made a mistake reading this forum makes me think so.


Don't worry. In about 20 years you should be back to where you started. Smile Seriously, just use Jorg's technique and you'll be fine. You will probably need several seasoning cycles. It's nice to know you're so compulsive about cleaning!
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PostPosted: Tue Jul 10, 2007 5:49 am    Post subject: Reply with quote

I never use any kind of soap or water to clean my cast iron skillet, which I use every day. First, I take a metal spatula like a hamburger type and scrape up any cooked on food. Empty the skillet. If there is still cooked on food that I can't scrape out, I set the pan on a burner and turn it on to medium-high heat and put a tablespoon or two of Kosher salt into the skillet. Shake the skillet to even out the layer of salt. Let that heat up until it begins to scorch, about 5 - 10 minutes. Then take the metal spatula and scrape the salt and burned on food around in the skillet. If the cooked food doesn't come off, you didn't let it cook long enough. Then, I allow the skillet to cool. When it is cool enough that I can empty it out without burning my fingers, I take some paper-towels and holding the skillet by the handle, over the garbage pail, wipe out all the salt and cooked on goop with the paper-towels. Wipe out all the salt. It is not necessary to oil the skillet before putting it away, unless you are going to put it in storage. To keep it from rusting, I put a generous coating of Minereal Oil or Mineral Spirits that you purchase in the pharmacy; not the hardware store. Maybe a 1/4 of an inch layer inside the skillet. Actually, you can coat the outside with the Mineral Oil also; I guarantee, it will not rust. To clean the outside of the skillet, have your husband take it outside and burn off cooked on carbon, grease, etc., with a propane blow-torch. This works so well for me that I stopped long ago experimenting with other methods.
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Watt
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PostPosted: Tue Jul 10, 2007 3:19 pm    Post subject: Reply with quote

Anonymous wrote:
I never use any kind of soap or water to clean my cast iron skillet, which I use every day. First, I take a metal spatula like a hamburger type and scrape up any cooked on food. Empty the skillet. If there is still cooked on food that I can't scrape out, I set the pan on a burner and turn it on to medium-high heat and put a tablespoon or two of Kosher salt into the skillet. Shake the skillet to even out the layer of salt. Let that heat up until it begins to scorch, about 5 - 10 minutes. Then take the metal spatula and scrape the salt and burned on food around in the skillet. If the cooked food doesn't come off, you didn't let it cook long enough. Then, I allow the skillet to cool. When it is cool enough that I can empty it out without burning my fingers, I take some paper-towels and holding the skillet by the handle, over the garbage pail, wipe out all the salt and cooked on goop with the paper-towels. Wipe out all the salt. It is not necessary to oil the skillet before putting it away, unless you are going to put it in storage. To keep it from rusting, I put a generous coating of Minereal Oil or Mineral Spirits that you purchase in the pharmacy; not the hardware store. Maybe a 1/4 of an inch layer inside the skillet. Actually, you can coat the outside with the Mineral Oil also; I guarantee, it will not rust. To clean the outside of the skillet, have your husband take it outside and burn off cooked on carbon, grease, etc., with a propane blow-torch. This works so well for me that I stopped long ago experimenting with other methods.


SO YOU ARE THE ONE WARMING UP THE PLANET UNNECESSARILY. Laughing Out Loud
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paul
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PostPosted: Sat Jul 14, 2007 8:13 am    Post subject: composition of the seasoning Reply with quote

I've been trying to season a cast iron pot with cocnut butter (sold as copha in Australia) which is almost exclusively saturated fats - about 98%. I have seasoned 4 times: at 150C, then 170C, then 180C, then 200C, each time for 2 hours and applying more fat between each baking.
It hasn't worked well maybe a very tiny bit, instead after the 180C baking it has started to show what looks like rust.
This makes me think that unsaturated fats are bonding to the iron in a similar way to how they become rancid - through the breaking of the double bonds in the fatty acid chains. The surface of the iron would be coated in a very thin hydrophobic patina. It could be black because of a 180 degree difference in phase change on reflection by the metal relative to the oil. metal should induce a 180 deg. change, but oil, no phase change.(I think). The layer of fat being thin compared to the wavelength of visible light will meand not much light is reflected - it will look a little bluish for heavier fats.
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Sat Jul 14, 2007 9:27 am    Post subject: Reply with quote

paul wrote:
I've been trying to season a cast iron pot with cocnut butter (sold as copha in Australia) which is almost exclusively saturated fats - about 98%. I have seasoned 4 times: at 150C, then 170C, then 180C, then 200C, each time for 2 hours and applying more fat between each baking.
It hasn't worked well maybe a very tiny bit, instead after the 180C baking it has started to show what looks like rust. . . . .


I don't think you accomplished anything until you did your 200C bake. The smoke point for coconut oil is 177C. Your 180C bake was only three degrees above the smoke point, which would still leave you with a sticky pan and no carbonized layer. You have to go significantly above the smoke point to get the carbonized layer on your pan. Take it up to at least 230C and see how that works. You should see a considerable improvement.
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