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Cast Iron Cookware VS. Steel -Metallurgical Question

opendieforging

Plastic
Joined
Apr 19, 2018
Hello,

We are experimenting with surface preparation of cast iron and forged steel cookware and finding some interesting qualities.

For the steel cookware (carbon steel as it's called in the cooking industry) we are hot-pressing a 1/8" steel (hot roll) plate and then pickling in acid prior to seasononing in an oven @ 500 degrees with grape seed oil. Customers are reporting that these skillets are holding their seasoning really well and do not need to be reseasoned.

For cast iron pieces, they come to us as rough castings that we are turning down on a lathe to give the cooking surface a smooth finish. Seasoning process is the same as the steel but the skillets are not pickled. These pieces do not hold the seasoning as well as the steel and it is flaking off in some cases. We are trying to figure out a solution to help the seasoning oil stick better while retaining the smooth finish that sets our skillets apart.

My theory is that the cast iron does not hold seasoning as well as steel because of the graphite in it and it's "self lubricating" qualities. Old cast iron skillets only hold their seasoning so well because of their rough surface.

Does this theory make sense, or it way off?

Any suggestions on a possible solution to the problem?

Thanks!
 
Maybe a different oil? maybe a different temp?

The only time I've ever seen seasoning on a cast iron pan flake off is
when the pan was seasoned with too much oil. Maybe multiple thinner coats?
Season them upside down to avoid any oil pooling.

Maybe a light sand blast, something very fine, baking soda? Once seasoned, it should
still be smooth..


sounds like a fun problem to have.
 
One other thought, I once got a cheap cheap set of "cast iron" pans, cheap, new and most
likely chinese.. I could never ever get any seasoning to stick to them at all, ever...

I think they were more steel than cast iron, and maybe the lack of porosity in the steel
kept them from retaining the seasoning.
 
Hmm interesting thoughts, and I would think the same sort of things but as I mentioned, we are getting great results with steel using the exact same process. We have tried many different heat/oil combos as well.
 
My understanding is that carbon steel pans are much easier to season, but the seasoning is less durable.

Some of the old cast iron pans were very smooth, but still hold seasoning very well. Assuming the metallurgy is okay, I doubt surface finish is your issue.

I second what Bob said about thickness. Most of the good seasoning I've seen takes 3+ very thin coats. Otherwise you get an easily removed gummy layer.

I would also consider the possibility that some residue is interfering with the seasoning process. I'd probably try giving one a dip in cleaner (acid? alkaline?) and then seasoning.
 
The only experience I have with cast iron cookware is that you should never wash it with soap. If you do you will lose the non stick capabilities. I have welded up quite a bit of cast iron and I do know that it is hard to remove the oil that is absorbed into the casting. I am pretty sure that cast iron is quite porous. That being said there may be something going on with your finishing process. I know if you machine oilite bushings you need to be careful not to "smear" the pores especially when reaming. Perhaps your finishing is closing up the pores somehow and not letting the oil get down into the cast iron. You say the smooth finish you have is a trademark of your product. Maybe it is too smooth.
 
A thought,...brought about by vague memories of a similar problem from 45+ years ago.

Are the founders (casters) coating the inside of the mould with a graphite (aka plumbago) or similar compound prior to pouring? - IIRC it was used to seal the surface of sand moulds while at the same time let gases escape.

Some of the (many many many :eek: ) batches of castings a young and green Sami machined, not only cut differently, but the finishers had problems getting paint or whatever to behave nicely, ………..and again IIRC (sorry but it's a long time) it was discovered foundry that made the troublesome castings didn't pickle or wash them.
 
Hello,

We are experimenting with surface preparation of cast iron and forged steel cookware and finding some interesting qualities.

For the steel cookware (carbon steel as it's called in the cooking industry) we are hot-pressing a 1/8" steel (hot roll) plate and then pickling in acid prior to seasononing in an oven @ 500 degrees with grape seed oil. Customers are reporting that these skillets are holding their seasoning really well and do not need to be reseasoned.

For cast iron pieces, they come to us as rough castings that we are turning down on a lathe to give the cooking surface a smooth finish. Seasoning process is the same as the steel but the skillets are not pickled. These pieces do not hold the seasoning as well as the steel and it is flaking off in some cases. We are trying to figure out a solution to help the seasoning oil stick better while retaining the smooth finish that sets our skillets apart.

My theory is that the cast iron does not hold seasoning as well as steel because of the graphite in it and it's "self lubricating" qualities. Old cast iron skillets only hold their seasoning so well because of their rough surface.

Does this theory make sense, or it way off?

Any suggestions on a possible solution to the problem?

Thanks!

Dunno. Grape seed oil is a sort of wax-thrower. Polymerizes pretty easily.

Iron skillets or Wok I've always used lard or bacon grease. Resists polymerizing, but seems to carmelize.

See also what Coconut oil does for yah. I use that on Stainless.
 
its my belief those pan types are never really fully cleaned. that is you leave some fat and oil thats charred on the surface, and after a few dozen times of use its seasoned. if a few spots flake off i wouldnt worry about it
.
some people cant accept pan not "clean" and continue to clean the seasoning off and have to redo it often.
 
I'm going to take a wag that you are fairly young based on the comment that old cast iron skillets have a rough surface, yeah, the "old" stuff from the 80's till present. I have quite a bit of cast iron cookware from the 30's and 40's, the surface is very smooth, and it weighs about half of what the modern stuff does.

In cleaning and reseasoning the older pieces, I find some take the seasoning quite well, others do not, I don't know why.
 
when i want epoxy to stick to cast iron i rough it up with 50 grit sand paper so it has something rough enough to grab
.
pickling or acid treatment may be roughing the surface too
 
its my belief those pan types are never really fully cleaned.
Except out of ignorance. Wife came down to the lovely smell of frying bacon one morning, only to see me throwing the last rashers of a whole package into the garbidge.

That's the sacrifice it took to re-season my older-than-I-am faithful Griswold after she ran it through a highly-effective Ohio-built Hobart dishwasher.

:(

"Cleaning" is relative. High-heat sterilized carbonaceous material is "clean enough", biologically.

Fast-forward to Belgian or "Spring" Swiss Stainless & c.

THAT I polish and white-vinegar de-lime. Every go. Which - oiled and pre-heated - makes it near-as-dammit "non-stick" off a whole different set of heat and food chemistry and physics.

Horses for courses, Cookware for cuisine. Run what you got for wot it IS.

All up to the food nut that grips the handle (AKA "chef"), not the maker's initial seasoning.

:)
 
Cast Iron I have seen is not machined.

Cannot see how seasoning would flake, as it is basically oil in the porosity

i am thinking machining makes it smoother than optimum for seasoning
 
Recall reading that older fine detailed CI had more Phosphorus in the mix as well.

I was thunkin'.. that the one reported as shedding all coatings attempted might have been smelted in China off scrapped Silicon-Steel transformer cores.

:)

Griswold, at least "back in the day", knew very well what Iron was fit for the cooking game. Lotta the lesser ones were thicker, heavier, and cracked anyway.

NB: Good stainless - and I mean REALLY good, as-in Swiss or Belgian, one French and one Italian maker.. think $700 + Woks and such ... will put most anything else back in the closet, once yah learns the witchcraft of it. I did say "oil and preheat"?
 
I was thunkin'.. that the one reported as shedding all coatings attempted might have been smelted in China off scrapped Silicon-Steel transformer cores.

Griswold, at least "back in the day", knew very well what Iron was fit for the cooking game. Lotta the lesser ones were thicker, heavier, and cracked anyway.

Seeing how they were made in "Erie, Pa"....I'll wager that they bought their coke from the aforementioned (now in trouble) "Erie Coke".
Making metallurgical coke.
 
Going back to what bobw and danielg said, flaking off of seasoning to me implies too much seasoning has been applied. I also agree the best I've used are older and are very smooth, something I wish I could go buy new as those good ones have been associated with females I'm no longer cohabiting with...I'm not one for flea markets and antique stores. The new stuff is much rougher in comparison, and while I don't know if it helps with retaining seasoning, it certainly is worst in terms of stuff sticking to them in the first place. What's your company? I'd be interested in your product.

The only time I've seen something like described is when trying to do as you are, season starting from scratch, baking on too much oil in the oven, vice regular use on the cook top. This created and goopy layer on top of the surface as opposed to impregnating the CI itself and I had to start over. I'm no expert though, I've only done it a couple of times, once after attempting to sand a purchased new skillet to smooth the horribly rough surface that was a bear to use, followed obviously by a good washing.

In proper use, the seasoning is not a coating that lasts. It should be maintained with every use if required, depending on what has been cooked. I tend to use olive oil, bacon grease, or butter, again depending on what's cookin. As such, I'd second thermite's suggestion; you don't need to do as much initial seasoning for your customers. You want to product not to rust during storage or shipping, using a food grade oil that is unlikely to go bad, but beyond that it's on the buyer to know how to use CI.
 
I'd suggest you don't need to do as much initial seasoning for your customers. You want to product not to rust during storage or shipping, using a food grade oil that is unlikely to go bad, but beyond that it's on the buyer to know how to use CI.

Amen. No matter WHAT was done to oil-season, hits my kitchen, it comes OFF for a from-scratch re-do.

Too much in the way of oils with toxic components have been recycled and mis-used, rust-inhibiting preservative coatings high on the list.

The one that put the awareness up ME was "a while ago" when an Aviation lube with lethal chemistry and/or additives was blackmarketed as cooking oil. Horrific results:

https://www.tandfonline.com/doi/abs...scroll=top&needAccess=true&journalCode=fnas20

More recently:

Toxic oil syndrome - Wikipedia.
 
There are a lot of different types of Cast Iron. Typically in Machine Tools components where wear was a concern a lot of New England machine manufacturers used a higher nickel content cast iron than one might see as opposed to ductile or malleable cast irons used more often in decorative or bulk castings. Cast Iron is by it's structural nature porous and green castings are usually pretty subject to change during the stress relieving period. Bridgeport Mfg used to just pile the green castings out back and let them sit in the weather for a year before using them. Other machine tool manufacturers use shot blasting to stress relieve. I know that some import machines have had trouble with coatings such as chrome flaking off because the underlying cast iron was too soft and prone to movement. So not knowing what cast iron is used it's hard to diagnose.

I will say that at home we use several cast iron pans on a regular basis. The most widely used is a pan that was my Grandmothers and was probably made pre WWI. We never wash it with soap, the bottom is quite non-stick, and it's not as heavy as the 12 Inch US made frying pan I bought new post college, which we initially seasoned slowly, and have re-seaoned only once since. The Iron in the old pan seems denser, but thinner in comparison.

I know that many foundries had "special sauce" Recipes that the foundry masters kept pretty closely guarded.
 








 
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