Manually smooth Cast Iron Pans?
March 11, 2010 6:54 PM   Subscribe

My Cast Iron Pan isn't like Grandma's: Help!

I have few cast iron pans: Lodge 10" skillet, a double griddle, and a dutch oven. All of them have a pebbled finish on the cooking surface. Conversely, the round griddle and 8" skillets I got from my Grandma are smooth as glass. All of these have great seasoning.

But I've used the 10" skillet for more than 10 years, and the bottom is still pebbled. Do I need to machine these pans to get the "glass-like" finish?
posted by Marky to Home & Garden (12 answers total) 10 users marked this as a favorite
From what I've read, the old Griswold pans (as well as some others) from decades ago were machine-ground. Lodge just sand-blasts their cast iron, producing the pebbled finish. I have no idea if you could machine them yourself to get the finish you're looking for, though.
posted by deludingmyself at 7:04 PM on March 11, 2010

I use my lodge pans for crepes and omelets and they work great. If it's smooth and seasoned well I wouldn't worry about the finish.
posted by monkeymadness at 7:18 PM on March 11, 2010

From what I've read, the old Griswold pans (as well as some others) from decades ago were machine-ground. Lodge just sand-blasts their cast iron, producing the pebbled finish. I have no idea if you could machine them yourself to get the finish you're looking for, though.

There may be something to this. I have a Lodge griddle that I thrifted that has a slightly textured finish, but the no-name skillet my mom gave me recently, which she used for thirty years before she decided not to bother cooking anymore, has a very smooth surface. Could just be general aging, could be the actual way the pans were made.
posted by padraigin at 7:25 PM on March 11, 2010

no, seasoning is not going to smooth out a rough, metal surface. seasoning is only going to smooth things out @ a microscopic level.

i would not be shy about taking a hand-held rotary sander or a sanding block to smooth out the remnants from the casting process (you will not need a milling machine)

with either of these approaches, there's a lot of room for go for it! you'll have to try really hard to mess this up.
posted by DavidandConquer at 7:25 PM on March 11, 2010

How does the texture of the pan make a difference?
posted by aniola at 7:30 PM on March 11, 2010

Oh. duckstab already linked to the answer:

"Early cast iron was sold either polished or unpolished. Polished cast iron isn’t polished the way silver is, it merely has a surface that was sanded or machined to make it smoother. The polishing process reveals more of the internal pore structure of the iron, and these pores make the seasoning adhere better to the pan. Polished cast iron is slick like glass when properly seasoned. "
posted by aniola at 7:40 PM on March 11, 2010

In Erie Canal days, pots got scrubbed with a handful of gravel. A few years of that would create the surface you describe. I myself prefer a glassy surface.
posted by Riverine at 8:35 PM on March 11, 2010 [1 favorite]

When I was a kid, a I remember the cast iron skillet my folks bought from IKEA had a pebbly finish. Kinda rough and definitely grey coloured. I was over their place last week - maybe 20, 23 years after the skillet was purchased - the surface was topographically flatter than Kansas - it had an extremely even curing. The entire thing was a dark dark iron.

In order to get that kind of `glass` finish, you need to use the pan a lot. A shortcut method is to clean it well, rub in oil, bake at 300`F for a couple of hours. Wash without soap or detergent. Repeat many times.

Quality cast iron stuff is typically Ooold since making a GREAT glaze on iron simply requires lots of repetition of little things.
posted by porpoise at 9:56 PM on March 11, 2010

I recall seeing a "how do they make that" type show where they did the Lodge skillets. They are put through a process that seasons them an absurd amount of times that gets them the way they are.

Correct me if I'm wrong here, but taking something that is machine seasoned like that with a pebbled finish and sanding it down seems like a really good way to remove a good chunk of the seasoning...
posted by Elminster24 at 10:21 PM on March 11, 2010

If you're willing to go to a bit of trouble and expense to improve your pan's surfaces, I might suggest having them shot blasted or shot peened. Shot peening of small to medium sized metal parts is often done in a blast cabinet, not unlike the abrasive blaster cabinets often used in metal and paint shops to clean oxidation and old paint from parts, prior to re-finishing. But shot peening uses heavier, much more abrasive steel shot, and shoots that shot towards the metal part surface being peened at much higher velocities than those used for simple surface cleaning and corrosion removal, to produce the micro-peened, compressively stressed finish so useful in cast iron products. Because of the higher velocities and larger, heavier media sizes needed to actually peen parts, instead of just abrading the surfaces, shot peening equipment is typically of heavier construction than simple media blast equipment, and often uses mechanical impellers, rather than compressed air, as the source of energy to accelerate the shot media. The part will get pretty hot as it is shot peened, and much of the surface texture will be peened down, into tiny, overlapping "dents" of surface compressed metal and carbon, setting up a surface stressed layer of hard, martensitic steel, perhaps 1 to 3 millimeters deep.

In common gray iron, the kind of brittle cast iron usually used in cast iron cookware, shot peening actually converts some of the gray iron to martensite, making the surface much harder and less porous than it would be otherwise. Subsequent heatings of the pan in seasoning and cooking slowly anneal this work hardened layer, as seasoning builds upon it, but unless you do something to regularly get the entire skillet or pot to red hot temperatures, much of the martensite will remain, in the compressively worked top layer of the item, for many years after shot peening. That residual peened crystal structure will continue to impart significant surface hardness, smoothness and crack/wear resistance as long as the pan is not overheated, and the surface seasoning on top of it remains.

Many general purpose machine shops have bead blasters or shot peen equipment, capable of treating your pans. I paid about $80 to have a large Lodge skillet shot peened some years ago, and it continues to perform well to this day; I had both the inner and outer surfaces shot peened, to achieve better crack resistance, but it is possible to have just the inner cooking surface peened, if you like. It seasoned a little more slowly than other Lodge pans I have, but over the years has developed a very slick, hard, jet black cooking and outer surface that is a delight to use in frying, and baking. I should note, however, that a significant cost of having parts shot peened can be set up and media/shot costs, particularly if the machine needs to be cleaned and reloaded with new media before processing your part; thus, if you have several items to shot peen at the same time, it may cost much less, per part, than what I paid.
posted by paulsc at 11:18 PM on March 11, 2010 [4 favorites]

The slick surface you're thinking of is almost certainly the product of machine grinding at the time of manufacture. I've owned several older iron skillets, and on some the perfectly concentric grinding marks were still clearly visible.

With so many fine old skillets available on eBay, I don't know why anyone buys lodge.
posted by jon1270 at 6:02 AM on March 12, 2010

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