I recently was given an old family cast iron skillet and noticed that the outside of it had serious buildup. Basically I can take my fingernail and lift several, thick, black pieces off. The inside of the pan is fine. I was wondering where this comes from and if this affects cooking on the pan. Also what would be the best way to remove the buildup? Thanks

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  • Do you have a gas stove or electric or induction?
    – The Photon
    Commented Jan 26, 2019 at 17:52
  • I've been using a gas stove. Commented Jan 26, 2019 at 17:53
  • could the pan have been used on open flame, e.g. been taken for camping?
    – rumtscho
    Commented Jan 28, 2019 at 8:54

5 Answers 5


The inside looks absolutely fine, so assuming you will protect that if you do any actual work on the outside I see a couple of routes you can take...

  1. You can ignore it & see if it will reach a new equilibrium with your own cooking equipment & technique.

  2. You can clean it off & quite quickly return the outside to a lesser seasoned state - as you're not cooking on the outside the seasoning is far less important, & as you've already discovered, the outsides of pans can get a lot more build-up over time than the insides*.
    You could attack it with sandpaper, or a drill & wire brush attachment, though you need to beware of the mess that can make if you do it indoors... or you could take it to somewhere that could shot-blast it for you. This is an industrial cleaning process, depending on abrasive type can be extremely vicious, but it's rapid & they could clean the outside back to shiny iron in 2 minutes.

You can then re-season the outside.

*You should have seen my old wok before my partner threw it away. I eventually forgave her ;)

  • 1
    Another aggressive mechanical attack is a drill-mounted wire brush or sanding disc. If you've got a drill they're both cheap
    – Chris H
    Commented Jan 26, 2019 at 19:36
  • I'd considered that as an option - & probably ought to add it to the answer, thanks... but I was just thinking about the mess ;) Sanding is bad enough. If you find somewhere that does shot-blasting [or one of the myriad varieties of it] then they've got extraction & filtration so you don't need to worry... & they'll charge pence for it, because one of the guys will just do it for you there & then, no booking, no real fee, just bung the guy a few quid.
    – Tetsujin
    Commented Jan 26, 2019 at 19:40
  • 1
    I've got a garage set up as a workshop, googles and masks to hand, so I wouldn't worry. I can see how that might not work for everyone. Even a big handheld steel wire brush might do something good
    – Chris H
    Commented Jan 26, 2019 at 19:55
  • 4
    I'm the only one in my entire extended family who never took up a manual trade. I learned quite young that it's simpler to find 'a bloke who can do that' than attempt it myself ;-)
    – Tetsujin
    Commented Jan 26, 2019 at 20:00
  • 2
    @GeorgeM - The 'why' is that it's shedding faster than a a labrador in summer. The 'why not' is covered in my first point.
    – Tetsujin
    Commented Jan 31, 2019 at 6:38

I inherited old pans with thick carbon build up. I built a fire in my fire pit and placed the pans above the coals. After all these were pans my parents used on campfires. I kept an eye on them until the carbon started flaking off. I would not place them on a roaring fire you could run the risk of cracking your pans. Now this is something I would not recommend if you have valuable cast iron. I have a friend whose grandmother would season her skillets in an earthen oven completely surrounded in fire. She did this for decades as it was her custom to give cast iron as gifts. She never once cracked a pan. She gave me a griddle to make tortillas on that I’m still using 20 years later.

  • I'd go with a wire brush on my drill press, but pretty sure your method works too. Commented Sep 16, 2019 at 23:57

Placing the pan in the oven during a self cleaning oven cycle will make the peeling layers turn to ash, and they can be easily scoured off using a steel wool scrubber. (Tried this from experience with a pan very similar to yours)

Unfortunately, this will require re-seasoning the entire pan.

  • The high heat won't cause the pan to crack? Commented May 16, 2019 at 11:44
  • 2
    @CarlEdwards cast iron is able to withstand temperatures over 500C without any problem. Put it in the oven when cold, start your self-clean cycle, and make sure you let the pan completely cool in the oven - don't try to cool it down quickly by other means.
    – canardgras
    Commented May 16, 2019 at 12:50
  • While this will work, it's unnecessarily harsh. It's easy to scrub off the outer buildup without stripping the entire pan.
    – Sneftel
    Commented Jan 26 at 14:26

I inherited some cast iron pans from a fishing lodge that were pretty cruddy on the outside. The insides were great. I used some oven cleaner on the outside only, left it on for about 20 minutes, rinsed it off, and then used my wire BBQ brush to scrape off the residue that came off easily. A lot, which was baked on so well it was part of the pan, remained. It worked well, but I hope I have not committed a grievous sin by using oven cleaner. I’m giving the three pans I did this to a good season right now.

  • It doesn't sound like the oven cleaner really helped (or did anything) here. Scrubbing with a wire brush was a good idea, though.
    – Sneftel
    Commented Jun 11 at 15:57

I am always looking for things to break out my dremel....iT would work perfectly on a cast iron pan that has build up...In fact you could used several different attchments to really take off the black bumpy stuff....I would have a ball if I had a cast iron skillet that was old and needed this I have it looking new in no time at all and you could too !! grab your dremel and get to work !

  • What tip would you use for something like this? A wire cup? Wire wheel? sanding disk? And are you talking about a large dremel, like the trio (more rotozip sized), or something smaller like the original stick ones?
    – Joe
    Commented May 15, 2019 at 13:24

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